 welcome you for this new gift. I know we hope that we will meet you maybe next year but today and all the week we will have a virtual gift and I will want to thanks to Alberto to Alberto Montanari who is a EGU vice president who is with us to open this this gift today so I'm going to leave Alberto to tell you some words to begin this new edition Alberto please. Yes thank you Jean-Luc and I also would like to thank already now all the organizers of this gift workshop. It's a pleasure for me to substitute today the EGU president Helen Glaves who is not able to join us today to bring forward from the EGU governance. Actually the gift program is one activity that EGU is really motivated to promote further because we think that education is extremely important to create the proper background for the future researchers on fundamental issues related to geosciences. EGU is a scientific association we mainly focus on research but we realized already several years ago I would say since the inception of EGU we realized that in order to effectively support science we need also to contribute to education. As I said to create a proper background for the students already in the period of the high school this is why our motivation to support the gift program is still increasing. We are really motivated to promote it further and the motivation increased also because we became aware by looking at the gift workshops of their success and the success is granted by the attendance by the interest of the teachers like teachers like you today and for this reason I'm really pleased to thank you teachers for attending and also I would like to thank all the persons who are presenting who dedicate a lot of efforts to make our scientific world accessible to teachers and the students. This is really something that EGU is motivated as I said to promote further and I really hope that you can take the best of the outcome of the possible outcome from this workshop even if it's held again in virtual mode. These workshops in the past of course took place in a physical presence as you heard during the past two years this was not possible. We are really looking forward in the future to a new mode for delivering these workshops that combines the advantages of the virtual attendance which of course has some benefits combines these advantages with the advantages of the physical attendance which gives more opportunity for an interaction besides what is the workshop time. So once again let me thank very much the organizers and the presenters and the attendance. I also would like to address a special thought to Chris King but I think that probably Carlo will say something about that. I just would like to say that I'm really thankful to Chris for his past support and I really feel that Chris is with us today. Thank you very much once again. Thanks Alberto for this opening moment. For everyone of course this gift is a special one. It's a special one first because it is the 20th anniversary of the gift and I am asking to Carlo to tell us more about this celebration of our 20th anniversary of a gift. So please Carlo. Good morning this year it is the 20th anniversary of the committee on education and gift workshops so some colleagues of mine asked me to give a few words about how this committee was created and of the major steps which were achieved in this last 20 years. The committee was created in 2002 with the aim of bringing state of art science into tomorrow classroom and I was lucky when I proposed this to EGU to meet Andre Berger and Arne Richter who supported the idea from the very beginning. We certainly were inspired by the teachers workshop of the American Geophysical Union but from the very beginning we wanted to have our own personality so contrary to what was done in the States where the teachers came from the place where the meeting was obtained we wanted teachers to come from as many as possible different nations meaning that we had to fund them both for travel and living expenses. Then we wanted the gift workshop to focus every year on a single general theme that changed this year and of course compared to the American we had the challenge of a multicultural multi-language audience which were met from the very beginning and so that we could include teachers from Europe and elsewhere in the world. So in 2003 the first gift workshop took place in Nice and Jean-Luc Berger and myself were probably the two oldest members of the committee to be there and then followed the six years of our growing success. For many reasons first of all the General Assembly moved to Vienna which was much more favorable for gift because of Eastern proximity of Eastern European countries and so that the number of requests increased to the point that we had to limit the number of participants to about 8085 both for financial reasons and also for space availability in the international center in Vienna. This gives you an idea of the different topics which were about the first five or six years you know history of the earth, polar region and so on. Why we had such a success also because not only because it was new but we introduced hands-on activity to be performed by the teachers during the session and also a poster session which is called Science in Tomorrow's Classroom where the teachers were invited and encouraged to present their activity in school particularly out of the official program activity which was open also to known teachers participant there and one thing which attracted the teachers was that we selected really top scientists to address them including two Nobel Prize winners Paul Krutzen for the Anthropocene and ozone studies in the atmosphere and more recently Michel Mayor who discovered the exoplanets so planets turning around the sun which is not our sun. In 2009 and 2010 two major steps were done first of all we registered the gift topical presentation on video and then we moved to marry the Yucatan first time out of Europe in the footsteps of Alexander Funovost this means that the EDU was organizing there the Alexander Funovost topical conference and we joined this in 2014 in collaboration with UNESCO we moved first time to Africa at Port Elizabeth in South Africa and then a series of international gift workshop to place Africa again in Ethiopia here is a view of the participant in Botanical Garland at Addis Ababa when we moved to Penang in Malaya in Istanbul in Kutskow again in 2016 in Merida and Cape Town and in 2000 to the traditional gift workshop during the General Assembly in Vienna and every time we adapted the theme of the gift workshop so that it was interesting particularly for the for the national we moved to for instance ocean identification was important from Malaya because of the coral reefs which were deteriorating in 2012 Kutskow the preservation of world heritage sites in Istanbul we had high impact natural hazards and earthquake of course in Ethiopia we addressed the general theme of water which is a major problem in Ethiopia and finally in Merida again natural hazard in this year 2022 we started two capacity building gift workshop these are the largest program of gift workshop outside of Europe and it should have started in 2020 but there was a stop of two years because of the COVID pandemics and I would like to come back one second to the 2016 Cape Town gift workshop because it was associated with international geological congress to which Chris King also participated because he was part of an international committee and I took the opportunity to ask him whether he would become he would be interested in becoming a member of our committee and I was very happy on 9th of January 2017 to receive this letter which I left here so this is my last slide in 2017 Chris King participated to his first ever Chris sorry gift workshop both as an educator here you see in front of a different experiment he would demonstrate to the teachers and explaining the earth learning idea is fabulous site especially done for education and in the second picture here you can see Chris listening to a South African educator and these are the two aspects of Chris which have impressed me quite a lot he was a wonderful educator but he was also open to ideas and to methods of other educators and unfortunately Chris passed away on February 25 2022 and so from here I pass the award to my colleague Jean-Luc Beringer thank you thank you so much Carlo so effectively we cannot begin gift 2022 without fault and a tribute for Chris King well Chris King joined the EGU education committee in 2017 and he became in chair the following year of course Chris has started his career as a geoscientist working in Africa he moved into education become a specialist in earth science on the science teacher training team at Kiel University in the UK it was from there that he led the way in developing a number of geoscience education initiatives that culminated on his appointment as professor of earth science education at Kiel University it was in 2003 Chris as Carlo said was a so great promoter of geoscience education not only in UK but around the world he has created so simple and so effective tools to help researcher to help teacher to promote geoscience it is with this spirit he was also led the education committee in recent years his impact in promoting geoscience education was so evident naturally everybody thinks on earth learning idea how to describe earth learning idea I will say that is a treasure is a treasure of resource for teachers is a treasure because it's a huge amount of hands-on activity for schools and it's also treasure because it is a so great legacy for educators we have learned a lot from Chris and many new actions have been created under his leadership Chris brought with him a joyful enthusiasm and commitment that inspired a number of initiatives for the committee as the first generation of EGU field officer this first generation of EGU field officer you will meet them Thursday during the gift and it was it is a wonderful project to to have so many educators trained trained by Chris around the Europe and at B1 but Chris was not only recognized as an educator his calm his pragmatic approach was always appreciated by those who knew him and for me he often brought a so fresh insight of challenging problems Chris was a colleague a mentor and a friend Chris has shared so many projects advice and kindness around him he would have love to learn more from him but we are also truly grateful for the time we could spend together I would like to share with you one of these last messages that he sent us a few weeks ago a few weeks before he passed away so I will just let you read this message yes Chris you will be greatly missed and we will try to cherish your precious legacy Chris would have loved this gift this new gift or gift 2022 it was indeed involved in its conception and realization topic and form do reflect exactly Chris work and spirit well now it's time for the gift for the gift 2022 and I would like that costas members of education committee tell you more about this general introduction for the gift 2022 costas yes thank you Jean-Luc I'll be very quick because we are five minutes behind schedule and I'm telling you I'm worse than the Swiss so I'll clean now so it cuts up we had the this year 84 teachers not everybody is locked in as I see plus we have one class of students from a general high school in Calendry I have persons from 18 countries we have and my mistake here I say 10 excellent speakers we have more than that actually and we have around 14 and we have also two hands-on activities on Wednesday the one will be from will be presented by Jean-Luc who just spoke before me and the other one by the EGU field officers team don't forget please next slide please so well this workshop is about the influence of earth processes geological or climatic processes or whatsoever processes and the influence they have on how the human society and civilizations are established and progress or become extinct throughout the history and next slide please so we will start today with presenting some aspects of this very diverse team and then tomorrow we'll speak about climatic aspects Wednesday for cities thirsty about environmental history and Friday about ice and us that is glaciation and volcanoes and so we'll start with Ray dozer today and I saw he's logged in about the ecology of Pleistocene Europe as it is represented in Paleolithic cave paintings and the last slide please and and I would like to remind you and all attendees of gift that you can register for free to the general assembly which is the first time that takes place not at the same time as gift and it takes place in may and you can register and follow the sessions if you like to thank you and have enjoy the talks thank you costas thank you very much thank you so as costas said uh we will begin with a dozer from university of virginia so we are going to make uh back to the paleolithic cave painting uh mr dozer must be with us I have seen him are you there here yeah I am here welcome Ray and uh I think you can share your screen uh because try to to share your screen please okay good so this first presentation is uh as the title is completely clear for forever I am going to leave the stage to Ray dozer to to speak about this ecology of Pleistocene so please yes good morning or or good afternoon good evening wherever you are this is the first time I've spoken to a group uh this diverse and in this many places so thank you for inviting my participation again we'll begin this session with a little bit of an overview of the ecology of Pleistocene Europe as represented in the paleolithic cave paintings um uh just a bit of review to try to try to make my presentation fit in my my presentation may be a little bit different I'm not talking about civilization per se the theme of this year's gift uh workshop is how planets how the planet shapes history geosciences human society and and uh and civilizations um I'm actually here to talk about a time before history about the upper paleolithic prehistory of western europe uh specifically southern france and northern spain I'll do my best to respect the workshop theme as we explore the influence of geology and climate on the society on the society of early modern humans on the european continent uh note that I specify modern humans our earlier human relatives the neanderthals occupied parts of europe for at least 250 000 years before homo sapiens arrived uh we're learning more about neanderthal society and ecology with each passing year but this presentation will focus on our own species um a bit of a disclaimer I've done some archaeology in the southwestern united states but I'm I'm not a card-carrying archaeologist paleontologist art historian or geologist I'll be talking a little bit about all these things today but I am not one of these people I'm an ecologist with an interest in how other people living in other places and other times express their perception of the world around one and that includes the people who created the paleolithic cave art of western europe so I'm I'm not an authority on anything I'm going to talk about but I am an interested observer of these things an interested student of these things what are we going to discuss today we're going to start with the arrival of homo sapiens modern man in europe we'll talk about the environment of western europe at the time of their arrival the artistic capabilities of these early europeans and the subjects they portrayed in their cave paintings and finally we'll look at a series of questions about what what we can learn about these people by examining their artwork and I'm going to give you a lot of dates today some I'll some I'll say that some I'll express others are simply embedded in slides understand all of these dates or or approximate and they're subject to revision with the discovery of new sites and the dating of those sites they're subject to revision based on simple revision of new techniques new technology to establish dates for known sites modern humans arrived in europe about 50 000 years ago dna studies of people living today indicate that modern humans migrated from eastern africa to the middle east then southern and southwest asia and then finally to the new guinea in australia followed by europe and central asia so modern humans arrived in europe relatively late in their dispersal out of africa we think they arrived in in western europe in in europe about 50 000 years ago new discoveries may push this date back a bit but 50 000 is a good number these people entered the very cold world of the late glacial maximum a world of tundra step open forest permafrost and glaciers they entered into a very cold world with a thousand feet or more of of of of glacial ice in northern europe a broadband of of tundra below that and a broadband of step further south from the tundra you can see this permafrost line extends all the way across europe and and asia most most but not all of the sites that were occupied by by the early europeans were south of the permafrost line obviously so they they moved into a very cold world a challenging world and they this obviously created a need for them to move migrate and occupy different locations on a millennial timescale they encountered a cold but highly variable climate in europe it was colder at sometimes than others the light blue indicates periods of glacial advance so you can see there was between 35 000 and and today 35 000 years before now and today you can see that there was a lot of variability and periods of extended ice ice advance followed by ice retreat ice advance ice retreat and so forth up to the day where we we think we're essentially out of the we're out of the lake glacial maximum it extended from 35 000 50 000 years ago up to about 8 000 years ago 7 500 years ago and we recognize different cultural horizons through the through this long period of time this diagram illustrates the relationship between climate change and and and the major cultural periods of the epipelialithic this is the environment into which homo sapiens walked after she left african the middle east this is an interesting interesting study published in in 2015 looking at population range and and density in europe we see that this was a simulation study based on an extensive review and incorporation of the archaeological history of the archaeological record these these two these actually several authors simulated produced a simulation of human geographic range and population density during different phases of that lake lake glacial maximum specifically they worked from 30 000 years ago to 13 000 years ago they found that the occupied home range of of the occupied range of of humans fluctuated considerably during this period of time it's expanding in some in some eras and contracting in others and it depended on climatic conditions the range tended to expand during warm periods and contract during colder population density also fluctuated through time from a maximum of about 330 000 soon after the entry of humans into europe down to perhaps 130 000 during a particularly cold era of 23 000 years ago a population rebounded up to maybe 410 000 13 000 years ago again this is a simulation that's based on an extensive review and incorporation of the archaeological record um so uh you can see that over much of this this period this long 30 000 year period of time there were vast areas where population density was either zero zero in the range of zero to one person per hundred square kilometers that's a low population density with one person per per hundred square kilometers modern europe with an area of about 10 million square kilometers would have a population of 102 000 people well i've been to events in paris where there were more than 102 000 people present at a given point in time for another point of reference new york city has an area of 472 square miles of 1200 square kilometers at one person per hundred square kilometers that works out to 12 people in the city in new york city many of you probably have seen new york city versus the 2020 population of over 8 million so this was a period when human population range and population density varied dramatically these people did not live in crowded conditions well these early early humans encountered a fauna in europe of absolutely breathtaking diversity i refer to this as a veritable Arctic serengeti much of the upper paleolithic art we'll discuss today focused on animals the Pleistocene megafauna there are literally thousands of examples of engraved drawn painted and sculpted upper paleolithic examples of upper paleolithic art and almost all of it represents the animals that populated the mammoth step landscape early man obviously drew profound influence from the animals around which he lived this image depicts a late Pleistocene uh what's referred to as a mammoth step landscape in in northern spain with you can see mammoths woolly rhinoceros unequivocal some kind in in the back and and two cave lions feeding on a on a on a reindeer uh so this is the essentially the landscape into which these early humans broke into europe Pleistocene megafauna of europe was a breathtaking diversity of herbivores creditors and a variety of other smaller smaller smaller animals um the this is the these are the animals that these that these uh early europeans encountered lived with relied upon feared and had to deal with uh in their daily lives now these early europeans obviously uh entered into this new world bringing with them a complex brain advanced cognitive ability complex spoken language control of fire efficient new lithic technologies new new weapons they brought with them needle sewn clothing the ability to organize complex social activities and an understanding of the benefits of the division of labor we know these things because of of of what these people left behind there's no written record of course but the the the uh the archaeological record they left behind is utterly consistent with uh with with this list of what these early europeans brought with them they also brought with them the ability to create what we now call art they knew how to draw how to paint how to engrave sculpt and carve they were very adept at all of these artistic techniques and of course what followed was a truly remarkable flowering of both uh mobile art for example effigies designed to be carried from place to place and parietal art art placed on a rock surface or cave wall and it's the parietal art that we're focused on today these early modern europeans occupied a mountainous landscape occupied occupied a mountainous landscape of karst geology there was abundant water rock shelters and deep caves i think of it as being much like the the shenandoah valley here in in western virginia uh this slide shows both the cavernous entry into uh uh les comborelles cave in uh dordon france and the southwestern france and the valley setting in which the cavern sits this location provided shelter water plant resources an abundant game near a shared water resource if if you were living in southern france 50 000 years ago 40 000 30 000 years ago this would be considered uh this would be considered fine living for the most part the these early humans lived in rock shelters and they painted in caves we found some art some parietal are in rock shelters today these are shallow depra relatively shallow depressions overhangs if you will in cliff faces and mountainsides they provided shelter from the weather they and they and they always provided light if the sun was shining these these rock shelters were lit if the sun were shining it was likely these these shelters were warmed they were protected from rainfall snow precipitation of all kinds they provided a good place to live it required less it required us only a small amount of of fuel to to be able to occupy and warm and and modulate the temperature of these rock shelters caves well tended to be deep deep recesses in rocks or surfaces a cave could be they were poorly lit often cold sometimes wet they could provide a place to live but it would require a lot of fuel to provide fire and heat and as and they could be dangerous places the cave the cave might might cave in surface the rock the ceiling might cave in they were dangerous places so these early europeans lived in rock shelters and painted in caves they devised a host of now familiar drawing and painting techniques this was not doodling they knew how to outline contour line cross contour parallel hatching cameo and intuglio marking modeling foreshortening carving and relief carving they knew all of these things they had they had a a full tool kit of artistic techniques and tools they either brought those things with them or they or they learned them soon after arrival they acquired them soon after arrival so what subjects did these i i say jar just uh choose to represent in their art plants no not very much no you we don't find plants clouds no we don't find clouds one another no they didn't they didn't paint one another at least we have no we have very little record of of uh human figures in paleolithic art landscapes no they didn't provide scenes no they chose to paint pictures of the animals that shared their eyesight landscapes humans very seldom show up in cave paintings and then usually as some sort of fertility symbol often female genitalia less frequently male genitalia fish and birds show up rarely mosaic figures in only a few locations they painted engraved and carved representations of the magnificent mammals which surrounded um uh which which surrounded them so abundantly uh hand stencils finger doodles and techniform or or geometric shapes accompany figurative forms in many of these caves um and there's increasingly it seems the some of these techniform shapes may have been produced by neanderthals uh there was a recent study uh that analyzed the co-occurrence of 3300 different figurative forms in 84 caves and rock shelters in western europe so this is the the motifs that showed up in these in these poly thematic panels in these 84 caves and rock shelters uh what you see is that uh cave art was dominated by horses and bison uh there were far more horse and bison representations than anything else uh and following horses and bison you you find a long list of of of other of other mammals i'm sorry of other herbivores uh and then you get down as to anthropomorphs uh maybe human figures of some sort and then reindeer come after anthropomorphs and then you get down to the to the uh uh to mostly the the carnivores the predators with which these people live uh and uh so what is often said of these people is that they painted horses and they ate reindeer there's little correspondence between the food remains the the the bones found in cave in cave environments uh and uh and the paintings that occur in those environments there's little correspondence there again they painted horses but they ate reindeer there are approximately 260 known painted cave sites in europe concentrated primarily in france and spain there are no uh there's no telling how many more caves are have yet to be discovered many of the of the paleolithic caves have been subject to rough collapse or rockslide sealing sealing off the the uh sealing off the entries this has of course made caves inaccessible and uh and served to protect the art contained therein occasionally a new cave is discovered usually by accident the most recent discovery was chauvet cave in france uh located it's not on here but it's located right right here right about where i've got my pointer right here in southern france uh it was discovered by three spelunkers only in 1994 uh and chauvet is now it's the most recent most recently discovered painted cave and it's now considered to be the sistine chapel of cave art the work is so fine and and so extensive the world's attention uh cave art has been the subject of study since the early 1800s but the world's attention was drawn to it with the discovery of lasco cave in in 1940 in that year four young men who are circled whose faces are circled in this photograph from 1940 they literally found this this cave by by following their dog robot uh through what they thought was into what they thought was a fox den it turned out to open into a large cavern and when they when they ventured inside deeper inside they discovered that it was it was the walls and ceilings were covered with with uh figurative representations of of of Pleistocene mammals so uh this was discovered in 1940 and uh was considered to be the the the most the grandest representation of presentation of of Pleistocene cave art uh and it held that reputation uh until the discovery of chauvet cave almost uh well a half century later um by 1948 lasco was open to the public and it was then closed to the public in 1963 because of the degradation that was being observed uh from the entry of people on the imported bacteria and microbes and dust and other things so you can see lasco today in what's called lasco for representation of the of the cave a reproduction okay this slide provides a link to a spectacular virtual tour of lasco we don't have time for this tour today but I highly encourage you to take it yourself when you have 15 minutes the tour this tour is guaranteed to inspire your interest in caves and the people who painted them so I strongly encourage you to to take a look at this just click on this vimeo link down here I believe it'll still get you to that uh to that tour oh geez I I didn't mean to do that okay okay let's delve into some specific questions about the about the cave art and artists were both sexes involved in cave paintings was this a man's world or were women and children allowed in how skilled were the artists did the painters actually accurately portray what they saw did these artists tell stories and portray events from life did they record history uh why did they paint on the cave walls this is an interesting study and to make to to make it a little shorter to make the story a little shorter there is a basis for recognizing the gender of of hand prints these type of of hand of hand paintings that hand stencils that were left on a lot of cave walls and based on the geometry of those of those of those prints and the relationship of one finger to another snow in 2013 developed an algorithm for analyzing hand architecture and analyzed a bunch of these hand stencils from eight european caves 75 were classified as adult female hands clearly females were involved in the creation of cave art and the the testing of this method suggests that that this number is probably pretty good the algorithm is actually capable of of of determining the gender of of one of these hand stencils so 75% were classified as adult female hands so women were in were in the caves they participated in some at some level in cave producing cave art in other caves we actually have footprints of children so we know that children were at least admitted to the caves and perhaps involved in in painting how skilled were the cave painters as artists that is could they portray feeling motion and perspective i'm going to let you judges for yourself from viewing a few selected images admittedly i selected these for a purpose uh what do you see here when you look at this when you look at this knowing that it's ice age art knowing something about the landscape on in on which this art was produced what do you see uh this is uh from peshmerl cave it dates about 25 000 uh bce bce although this is just the outline of a head and trunk and upper back of a mammoth it has it has been uh superbly done and it evokes the animal with a minimum of brush strokes this is to my eye this is a woolly mammoth i don't to me there's no question what this is uh the smudging of the head and and and and back uh whether deliberate or accidental does not detract from the worth of the image adds to the power that it is a woolly mammoth this is a spectacular engraving uh in the cave of les combrelles in southern again in southern france uh it's particularly it's a particularly well known engraved image of a reindeer spectacularly detailed with a massive rack of antlers of us uh clearly a penis engraved as a on a male and it the head is about drink appearing to drink this is called the drinking uh uh reindeer appearing to drink from a crack in the in the uh in the cave wall clearly this engraving was done with great detail and it was clearly placed in a location where this image this is it appears to be a drinking reindeer drinking from a source of water uh portrayed by a by a crack in the cave wall this is the famous red bull from Altamira cave in spain 15 000 years old it depends depicts a bull bison in prime condition in the great hall of polychromes in Altamira uh note the use of both red and black paints to represent the animal in a in a bold manner and the placement of the image on a bulging portion of the cave wall uh to give the animal depth and and and bulk is this an animal to fear or admire we don't know whether they feared it or admired it i suspect they did both but clearly this artist chose that place on the cave wall to to portray this this bison and portrayed it in a dramatic manner and placed it to maximize the the the drama and the impact of this piece of art this is the uh famous charging bull from Chauvet cave France it's probably 32 000 years old that's the best that's a good day it's rendered in black on a white surface a white background and once again uses the stone surface and smudging to portray depth and bulk this is meant to portray a massive strong animal more importantly though you can see there are multiple there at least two sets of legs portrayed here this creates an eight-legged beast intended to depict trotting or running when i look at this image i see the two overlaid images two two bison's eight legs but clearly i see a running bison here i don't know if you see that but that's what i see this is an animal on the move and this is the cross bison panel from last go dated about 17 000 years the artist took advantage of the cave surface texture and relief to create perspective and the illusion of movement overlapping the overlapping or repeating limbs coupled with the flickering light of moving torches help the animate the work and again it's placed in a in a on a portion of the cave wall where you are seeing two two bull bison literally running running running at you from within the cave wall again these are animals on the move it creates the illusion of galloping at top speed toward the viewer the swimming the swimming stags here we have five stag heads probably what we would call red deer today and they appear to be swimming perhaps in a river portrayed by this crack or crevice in the in the cave wall uh is this five stags swimming at the same time or is this one stag shown in motion what whichever it is it's exquisitely executed on on this on this wall and finally this is the great black bull oryx from last go this is a nice painting it's it's an impressive rendering of a black oryx of a bull oryx but the important thing about it is that it's rendered on the ceiling of the cave four meters above the floor and it's executed it's five meters long this is a giant representation this is much larger than life size bull oryx were large this is even larger the body proportions aren't perfect but they're not bad this work truly took a village to accomplish someone had to provide the light someone had to had to uh collect the poles or the timber to produce a scaffolding someone had to create leather straps to to to tie the scaffolding together someone had to build the scaffolding there were holes bored into the cave floor to to provide placement for the scaffolding this took a this took a community effort this took a village to do there was some social organization there was some division of labor this was a massive undertaking to create this thing this is not just another image of a bull this is an this is an image placed in a way that it took it took social organization to accomplish this is uh to my mind this is the most thrilling image in in last go uh did the cave painters accurately portray what they uh what they observed around them um did they represent locomotion realistically that's one one one test could they represent locomotion or walking realistically um this is uh one of the i'd say cutest images in in in all okay well everything i know about this is the freeze of small horses uh this is a freeze of of five diminutive horses this entire painting is only a meter tall all of these animals appear to be in motion their legs uh they're not all their hooves are on the ground they all they're all going somewhere every every one of them has at least one hoof off the ground and again it's a very diminutive portrayal the freeze of small horses well uh this is one of those things where sometimes you publish a paper that lasts forever edvard mybridge uh 1886 published a photographic study of quadruped walking uh he discovered the left hand left for right right hand right for a footfall formula for quadrupeds uh based on his analysis of literally thousands of of photographs of of a quadruped locomotion uh more recently harvath at al and 2012 analyzed the footfall patterns of horses in three different groups of art modern pre-mybridge modern post-mybridge and prehistoric they examined a thousand quadruped walking depictions to determine the correctness of horse gate portrayal they looked at horses where horses shown with the right footfall pattern uh eight ten minutes more ten minutes all right yeah thank you pre pre-mybridge 17 percent uh correct uh another even da Vinci sometimes got it wrong portrayed the footfall pattern incorrectly post-mybridging about 42 percent uh so uh artists clearly learned from what mybridge learned had observed uh some of them learned from my modern taxidermist about 49 percent paleolithic painters 54 percent correct these people were were indeed close observers they were they were close observers of what they saw around them and they were able importantly they were able to translate those close observations into accurate portrayals of of of the animals they they painted uh they they were able to translate this into art did cave artists tell stories or portray events from life did they record history that is did they express narrative or simply paint images this is where uh this is where interpretation becomes a little more challenging there are no clear unquestionable hunting scenes or family gatherings or celebrations or vistas represented in paleolithic cave art there are no scenes of travelers gathered around a a waterhole this is not to say they weren't portraying a scene they had actually witnessed or an experience they had shared but simply that they weren't they were portraying it in a somewhat abstracted representation there are no there are no family portraits there are no family gatherings in paleolithic cave art this is the mystifying shaft scene located located in the shaft of the dead man in lusco this is one of the most uh mystifying uh evocative scenes in all of paleolithic cave art most literal interpretation is that the bison disemboweled by the spear uh has somehow has gored the the hunter however a number of images and symbols that remain unexplained strongly suggest other layers of meaning the bird-like head of the of the of the human this is an anthropomorphic figure with a with a bird's head the long erect penis of the of the figure of the stick with the bird's head on it the barb stick lying here uh the bird-headed stick uh and and there's this is a departing rhinoceros uh with uh of six uh uh dots behind the anus uh the remote and this is this is at the bottom of a 10-foot deep of a 10-foot deep shaft in the one of the deepest recesses of lasco cave the remote and inaccessible location of the painting also seems significant what does it mean a myth a historical incident a historical incident a warning to be careful when bison hunting what does it mean well we just we don't we don't know but it's it's uh it's as close to to narrative uh as we find in in cave art uh this is the freeze of lions in chauvet this is old this is ancient ancient ancient art uh it's been interpreted as portraying a hunt scene this may be narrative a pack or a pride of lions hunting perhaps hunting this this figure in the front here we don't know quite what that figure is it could be a rhino it kind of looks like a rhinoceros perhaps um but when viewed in uh in uh in in in flickering torch light the image does in fact appear to move thanks to the optical phenomenon known as the persistence of vision um i hope to test this idea myself when i visit the chauvet reproduction next month uh in uh in france uh again there's the suggestion if you see it in flickering light yes it it it almost looks like animation the why of cave art why did these ancient people create these images all of art conveys a message of some sort uh these these folks left no written record this was a time before history they left us with this art all art conveys a message it serves as a signature a warning a prohibition or perhaps a welcome it conveys a story a myth a vision or perhaps a metaphor either sacred or profane it affirms individual or collective presence at a location at a point in time communicates with one or more divine beings to establish a bond with the spirit world so art all art conveys a message of some sort there are a variety of types of messages that it can convey again we we have we have no written record in fact any or all of these interpretations may be correct at certain times in certain places but none makes a sense as a universal explanation let's just look at art for art sake maybe it's simply individual expression maybe it's totemism or animal worship an expression of kinship between the artist and the animal he or she is representing maybe a sympathetic magic magic they're trying to make the world as they want it to be they're portraying the world that they want hunting magic a plea for hunting success maybe representing the animal is is a plea for is a form of of praise for that animal and a plea for hunting success maybe fertility magic a plea for abundant prey destructive magic a plea for fewer predators they didn't paint a lot of predators so we're not sure about this but there had to be a reason for painting them maybe it's shamanism communication with the spirit world perhaps communication fueled by hallucinogenic plant materials are simply by the by the stale air in the in the depths of the cave it could even be a hypoxia from from the from the lack of oxygen with several people in a small cramped space and the burning of animal fat in stone lamps provide light and maybe heat yeah maybe the maybe they just simply lost it because their oxygen level blood oxygen in fact any or all of these interpretations may be correct in certain times in certain places but none makes sense as a universal explanation we weren't there they left no clear record for us beyond their art we can't we can't know for certain what they were trying to accomplish through their art or why they did it but generations of scholars and other interested observers have drawn inspiration from viewing this art and attempting to understand and appreciate these people who lived in a time before history i'd like to say thank you for your interest in patience and thank you to the egu gift education committee for providing me this opportunity to share my interest in a time before history uh this year's theme of the gift workshop again is how the planet shapes history geosciences human society and civilization we began here before history we've explored aspects of the influence of geology and climate on the society of of early modern humans on the european continent we've described some of the environmental challenges these people faced and some of the opportunities they experienced mostly we've explored some of the dimensions of artistic expression that arose when modern humans entered into a vast new world one last little some breaking news here this is now 2018 a cow like figure uh has been discovered in luban genji solid and cave in borneo in south asia and it's reliably dated at 40 000 years bce this is this painting of cattle like cattle like animal has been dated uh at least 40 000 making it the oldest known figure to rock art in the world okay thank you very much thank you ray for your interesting presentation you can close the sharing your screen okay thanks a lot uh well thank you for your interesting presentation well i'm living in france so i know a lot of places you mentioned in your presentation uh if you have if the participant have question you can share the question on the chat why not or so i i appreciate that for many of many of you this whole presentation is a case of bringing coals to newcastle you probably know them know the material as well or even better than i uh but i i appreciate your patience in letting me uh present a north american view of it all thank you i have i have a question ray about uh you we have seen a map and i see that the distribution of cave paintings is not very uniform in western europe uh there is a few cave painting or places in italy is it right if i i compare with spain and france or there are there are explanation of this distribution there are a few caves known um outside of france and spain uh france and spain are the world center but there are a few cases there are a few known caves known out painting caves known outside of this area uh most of those are much later than they're at the very end very end of of the paleolithic uh era so i didn't devote much as much i didn't devote much time to those caves uh but they're later they're much later i was more interested in the the cave art produced early in the occupation early in the modern human occupation of western europe yeah okay and of course more caves are being discovered all the time magnificent caves are discovered are discovered periodically chauvet cave discovered in 1994 by three spelunkers who followed a flow of cold air from a from a hole in the surface and discovered chauvet and it turned out to be the most magnificent painted cave and the oldest ever discovered you know generations of of french archaeologists many many of them more or less made their reputations by explaining the the evolution of cave art from relatively primitive stick art type type representations uh up to uh up to lasco 17 000 years ago the greatness of our of lasco well it turns out that that you know that's just probably not not how cave already evolved at chauvet was the oldest we have in europe and it is also in many respects the finest okay i have a quick one more question but a quick answer if possible is what about the chemistry of this of the corals used the paint yeah the the red they they they used red and yellow the red and black sometimes i'm sorry i didn't say this earlier they used red and black sometimes yellow the red was derived from iron oxide hematite the black was typically manganese oxide or sometimes just charcoal charcoal so they they they relied on on minerals to to produce uh to produce the paints that they used okay thank you very much um our gift continue but uh so we have a a short break now until three thirty so well seven five seven minutes to to have a coffee to have a elenico for our greek uh colleague for to have an expresso for our italian colleague and uh be back uh in a few minutes it's three thirty to welcome uh uh grant uh hyken and speaking about the geology and roman uh she needs one more thing so um i hope everyone is coming back after the coffee break or tea break i don't know uh it is our second presentation uh grant hey i can he's going to talk about uh very yeah sorry grant i can i can sorry i can and um okay it's time to to have a view about this uh geology and roman civilization uh and so grant you have a stage to to present your your slides now okay do you thank you to be with us this afternoon once more time do you want uh to be able to see me or not uh i think it's better for the record but uh okay okay i'll go ahead even the connection seems quite good so yeah okay um you're probably wondering why a volcanologist from the united states is dealing with rome uh to quickly state why back in the mid to late 1990s i was working with a group at los alamos on integrated urban science and my main interest was to look at how cities have used geoscientists in their management and planning and uh i took a look around the world to see which of the major cities involved geoscientists and how they were they were managed and i came up with two uh hong kong and rome and uh i have a very good friend ronato funichello who was essentially responsible for much of the use of the geosciences in the city of rome the management and uh he produced a magnificent monograph called la geo geologia di roma about that time and i was talking to him about it and i thought well i want to see how they did it so i asked if i could come on my sabbatical leave to spend six months in rome which i did and it was a great experience well i'm in trouble getting going here oh okay uh we'll start this with a scene that most of you have an area most of you have visited the trevi fountain uh why how does this relate to the geology of rome i just give a brief introduction here using the trevi fountain um in rome the aqueducts brought water in from mostly the apennines into rome into tunnels the uh most of the the plazas the piazzas had uh i'm getting my cat off the desk here ah okay the uh the one at the trevi was derided as kind of the village well it was not a very attractive site and basically the pobs wanted this to be a visually beautiful place if you look at the uh the aerial photograph of the trevi fountain you see essentially there's three streets coming together here which is possibly the origin of the name trevi uh looking at the fountain or standing on the street below you lies and we'll get into this later about six meters of rubble from previous occupations of rome and below that uh about there's a 60 meter deep channel from the ancient tiber and that was carved when sea level was much lower and then filled up the sediment as sea level rose the water coming in to the trevi fountain uh from the virginia aqueduct the the beautiful fountain itself is mostly travertine the travertine is local it comes from the banyeditivoli outside of rome the figures are of carara marble which is not from rome but from up along the tourney and coast where the famous carara marbles came from the people are standing on uh basalt tiny basalt blocks which are you know cover many most of rome streets they're called san pietrini and we'll get into that later uh it's uh our little introduction okay let's talk about the seven hills of rome the irony of the seven hills this is a view from the geniculum on the west side of the tiber looking across rome toward the apanines and the first of the hills the curianale uh sits up there and essentially these are parts of a plateau which we'll discuss later on how that plateau originated and that the the quote-unquote hills were separated by stream channels uh carving small valleys which eventually were partly filled up by man-made anthropogenic debris the uh going far there here's several of the other of the seven hills down below along the trees there you can see the tiber itself uh the most famous is the capital lane which was at one time the center of roman uh history and uh so sacred and it's it's just above the form if you've visited there okay down swinging around toward the avantine that is probably the most delightful of the hills because it's quiet which is unusual in rome in the distance are the albin hills the cole albani it's a large volcanic field which we'll get into shortly uh the what we see here okay on on the side on the geniculum where we're standing those are mostly tertiary sediments and uplifted along faults parallel to the tiber and actually controlling the path of the tiber here's uh a synthetic aperture radar view of what we're looking at the hills there they're not very spectacular hills the seven hills are mesas and that have been eroded and carved and above the tiber which is to the left the the plane of the tiber you can see going down through there and on the west side you see the the geniculum the and going up to the vatican which is just to the north there and a long line along which there's a major road which is a fault looking at it more traditionally aerial photo there's a little box over the trevi fountain not very big uh but on here you can see let's see i can't okay here we go see the uh the coliseum the coliseum uh the vittorio maniale monument above the piazza venezia uh tiber tiberine island and the circus maximus the charco massimo uh and the seven hills visible here's the avantine down through here uh trostevery through here in this area and the castel san angelo to the north here the uh there if you go to the eu r there's a museum out there where they have a magnificent model of ancient rome which gets updated every time they find a new structure of some sort and uh that's another one of the platform of it try to get this thing right here here we go uh tectonics in roman history for those of you in tectonics and i can talk to the two francescos about this there's the apennines uh through here rome is down here lago de brachianos over here and this cross section you see essentially that the apennines are formed by a whole series of major thrust faults and okay give you where we are there's florents we are ends up there and bolsana and so on essentially north south to north northwest southeast trending valleys along which there were roman roads but also essentially uh encasing much of the other many of the other cultures that surrounded rome like the atrescans and the campanines and uh to give you a scale here there's rome again ostia ostiantica which is a great place to visit um and on down to putzoli we'll talk about putzoli a little later for when we were talking about possible on a concrete but uh rome had to conquer all these people before they could expand their empire and they did timeline here uh part of it's covered sorry going back about uh 100 000 i go from 100 000 years to 10 000 years 10 000 years to on down to the present and then uh one down here calling showing all of the not only geological events but the historical events that occurred and major things that form the the uh the plateau around rome is actually the the albin hills which are very active throughout this whole period down to well recently from 100 000 years but the sabbatini field uh went from 300 000 years down to about 80 000 years and at this point one thing that helped control the shaping of the plateaus is sea level was 120 meters below the present and sea level began to rise continuing to the present and first occupation of rome was about 10 000 years ago uh beginning the whole scene and throughout this whole time the tiber delta keeps growing outward into the sea it has slowed since the mid 1950s when they started building dams in the tiber but the the tiber delta growth was quite rapid and they kept they had to keep moving their their major ports like austia austa which is now austia antica which is now along you know like four kilometers from the sea and throughout this whole time travertine a major construction stone was being deposited and still continues to be deposited down here i'll point out these are mostly geological events up here the little shields are major floods on the tiber the uh these symbols down here are major earthquakes one advantage to studying rome geologically is the fact that the romans kept great records so any kind of natural event was recorded and kept and down here you know first settlements of trust in this spell roman republic imperial realm pantheon constructed here the first st peters here and which is important is that rome was sacked by invaders from the north and had quite a bad time there for a long time baroque realm which is great for the use of various marbles that came through uh but the interaction between the geology or natural events particularly natural hazards and rome's development uh are very critical uh as a volcanologist one of my favorite topics here is studying the origins of the roman plateau the plateau let's see if i can get my well no don't want that okay that that that okay uh essentially going from the alderman hills you can see the caldera a major caldera up there and it's the formation of that major caldera that deposited many or most of the pyroclastic flow deposits which form the plateau going into rome pyroclastic flow deposits or from major eruptions in which the the depot the ash deposits are deposited as density currents and leave very distinctive deposits the uh they're called ignimbrites the ignimbrites are kind of unique in this region because of the the aquifers below the the the volcanic fields that are essentially carstic aquifers from the apennines you get a lot of interaction between magma and water and that produces not only the very energetic eruptions but very fine grained ash which is easily altered and is important in construction stone coming in later i mentioned the tibre river delta earlier it's uh was expanding through history until uh the middle of the 20th century um you see the apennines over there that's important for water sources and to the north is another large volcanic field the sabbatini volcanic fields and uh that has produced deposits coming in around the uplifted Pleistocene and and tertiary rocks on the west side of rome a little closer view here i mentioned i was talking about hydro volcanic eruptions the interaction between magma and water most of the craters here are the smaller ones the large one the caldera that was involved but later eruptions formed these smaller in the center there is lago di albano uh the largest one there filled with a lake all of that is is lago dinami and that is filled with water but they form what are called tough rings and that's basically lots of energy very low rim deposits and uh deposits going into the outskirts of rome um most recent crater is in the lago di albano and it's also a site where where there's been a lot of recent uplift uplift movement and increased release of carbon dioxide and seismic swarms so who knows when the next eruption is we don't know most recent eruption of any note are volcanic mud flows uh lahars if you're into into volcanology which came out of lago di albano and go in toward rome and they know the date because it overla the deposit overlies a bronze age settlement which has been being excavated it's interesting that the bronze age settlement where the excavation is is below a large ikea superstore which what the ikea people did was raise the store and so underneath is a large parking area and you can look at the the excavation and there's a little museum there it's very very tidy okay the deposits that make up the plateau on top of uh quite often ancient sediments from the tiber mostly from the albin hills on the east side there's a sample over there on the left of some of these in a quarry just outside of rome the uh they're mostly ignembrites and formed from the fairly large caldera forming eruptions on the top and we'll talk about this later is the capo de bovi lava flow from which most of the stone for the streets has been quarried on the west side the sabbatini volcanic field not used quite so much for construction it's uh more distant and but there's still these deposits that come around the the uplifted tertiary deposits am i doing in time here okay move along these ignembrites which form the plateaus upon which rome is built have left the major building stone tough t u f f not what the architects say which is too far which is not too far as an spring deposit and the romans excavated these large blocks for construction but the quarries are underground these underground quarries were there for a reason land at the top was far too valuable for development and for agriculture and too valuable to be used for open quarries so these these underground quarries underlie much of rome and it's a it's a hazard for new construction so before any new construction goes in they have to go around and drill and look for these things they're fairly stable because the roman engineers made sure that the that there were large pillars holding these quarries up today they're used for exploration some of them were used for churches and this one i show up here is used for growing mushrooms and there's an example over on the left with or not to funne cello in the front there uh which is uh one discovered you know fairly recent historic time and you can see the tool marks left by the quarryman the roman quarryman on the the bottom right is a catacomb again carved into the tuffs the tuffs are strong as building blocks but they're easy to quarry uh you can quarry the most of these tuffs with with a handsaw it okay the catacombs themselves very very large extensive and essentially these after they stopped using stopped burning you know people they had to start burying them so they bury these in these catacombs along with the little holes on the wall there for individuals uh i mentioned that the quarries they underlie much of roman's it's just amazing it's a huge network and occasionally one collapses and uh has to be filled some in some cases they when they're drilling they find a quarry underground quarry that has not been visited and they check it out and if they want to build something on it they quite often fill that spot with with concrete that's just a little example of what can happen either just too much weight at the surface or possibly leakage from sewers and water lines another major product that is unique and essentially created by roman engineers is pazzolano pazzolano is pazzolano concrete is made up of aggregates from these altered pyroplastic deposits mixed with cement lime cement and makes a very strong concrete and concrete that is resistant to to water and many roman structures like piers and moles and so on along with the sea are made of this this pazzolano concrete this is the pantheon uh if you want to see a nice concrete building not the build not the temple in front of it but the actual pantheon itself which is very thick walls of poured concrete at the top with the dome the poured the roof is made of coffers goes up to the locky list the open light to at the top and the as they go from the base of the dome to the top of the dome they use different mixes of aggregate starting with the heaviest lithic bridge aggregates at the base and when they reach the top it's the aggregate is pump pumps so it's very light road building basalt very fine grained basalt that came from the the alman hills and a major lava flow that goes on into the outskirts of Rome that's the capo de bovi lava flow it's called the capo de bovi because it ends at cecilia metallis tomb which has a carved bull on the entrance and the large blocks the basalt were used for major roads this is one near the port of majori not in very good shape a lot of erosion from traffic and so on to the more you know regular size along the apian way and if you look back at the geologic map you can see the ancient apian way following the lava flow itself and heading up to the south toward the not only the the tiny blocks that you see in roman streets the san pietrini are also carved of basalt and work are from the quarries along the apian way but today most of them are imported from other countries quite often china so some of the repairs you see on the the roman streets are blocks that aren't Italian travertine um really beautiful stuff and uh essentially if you look at the geologic map there's tivoli on the right actually roman's off down to the to the left and down and there's a major strike slip fault that comes out of the cornucleini mountains and heads on down and I think goes underneath the the alba the elbin hills and as I showed on that historical map for the last 165 000 years or so the springs coming up are loaded with carbonate uh bicarbonate and a lot of carbon dioxide and have been flowing out into this basin the aqua albule basin near tivoli and leaving beautiful fine-grain travertine and this is a travertine quarry out near tivoli and uh you can see the the blocks that cut they're quite often used for monday and things like street curbs and so on also like in the case of the uh the trevi fountain construction of and for bridges this is the ponte chestio across the tiber and uh all travertine the uh I mentioned that there's a lot of carbon dioxide so a couple of my associates were visiting the quarries one saturday when you're the lake there and uh there was an earthquake and a lot of carbon dioxide was released and they ran out of the quarry because they would have been suffocated had they stayed in the quarry and actually there's a lot of carbon dioxide coming up in the albin hills and occasionally you find a dead animal of some sort okay key to realm success uh water lots of it throughout realm you see these fontanelli which are just constantly flowing you can drink it you can wash your hands in it you can use it to wash your car but there's a lot of it and to show how that has essentially this saw the sources which are in the apennines were developed and essentially drove the the success of the roman empire at the start before they started building aqueducts there were springs within the city you can on the left are millions of inhabitants on the right uh so you see a b essentially cubic meters of per second of water coming in and until they first built the first aqueduct out of the apennines the apien it didn't grow there's a there's a the broken line is showing population the solid line showing water supply and you can see it kept growing and growing and growing as the as more aqueducts were built and until the invasion of the quote unquote barbarians sorry guys who destroyed a lot of the aqueducts and part of it was to essentially drive people out of the city they didn't have any water and so they were back to essentially using small springs in Rome why didn't they use the tiber apparently the tiber was polluted and the water supply was not drinkable and it wasn't until like the i think it was the 14th or 15th century that the pope started having the major aqueducts rebuilt and you can see the rise in the public now uh today a few of the aqueducts are still used but most of the the water is coming through steel piping from the same sources in the apennines sources mostly up there were one two uh in the apennines carstic terrain and that carstic terrain are very you know very large springs flowing there's also some water coming in from the albin hills to the south and the sabbatini to the north today actually one of the sources of water coming in from the west is from lago di bracciano up near the top part of the of the image aqueducts incredible engineering i mean the Romans were fabulous engineers and probably still are but you get up to the source in the apennines you collect it and you start running a channel toward Rome sometimes tens of kilometers through complex terrain and to keep the flow moving they had to have a slope of one meter per kilometer and they did that they had surveying instruments that they used successfully and when they had to dig a tunnel they had excavation shafts and settling pool and then on into Rome where the water was distributed you can go to the aqueduct park just outside Rome and see what's left of many of these aqueducts one of the reasons they needed so much water is that the the public loved their thermal baths this is the Jeremy did caracola the baths of caracola and uh they had hot water they had tepid water they had steam rooms of tremendous construction on the other side the not so beneficial water were the floods the flooding was pretty regular until the mid 20th century this is piazza novota in the flood of 1870 and here's a map of the flood itself you can see the piazza Venezia down there uh St. Peter's on the left and scattered struts this region the Romans had left uh marks and columns that showed the water depths for various floods and an example of this is on the church of St. Maria so from Minerva that's just a cross the piazza from the pantheon and it shows the level of the water in the flood of 1870 which is close to four meters so if you lived on the floodplain it was not a good place to be okay the other thing I want to talk about is debris uh if you there's a thick great thickness of anthropogenic debris if you're an engineer you hate it if you're an archaeologist you love it this is in the form that's caviting down it's through the debris into various uh Roman structures how thick was it on the left is the thickness and meters through is through time this is in one spot in the Campo Marzio and you can start in ancient Rome up you know on up like eight meters on up to 14 meters on up to 18 meters on up to today so it's uh there's a lot of debris and because of that debris many of the major monuments and historical buildings look like they're they've been buried developed in a pit this is the memorial pyramid near the piazza San Paolo I think near the English cemetery and it looks like it's in a hole it is because the whole street has actually come up about three four meters relative to the pyramid another example the church of San Clemente looks like it's in a hole and whereas the rest of its debris now as I was talking about the San Pietrini the little the salt blocks that make up many of Rome's streets you can see examples here you know at the bottom of the photograph going into the church the church itself actually overlies a Roman temple first century BCE Roman temple so things keep adding up building up sample here and developing the metro line metro line B this is a geologic section the man made debris are the slanted lines at the surface and you can see that it's it's pretty thick and there's if you get down near the cavore station there's actually a ravine that's filled with 20 meters of debris and that goes on down to call the sale the debris sometimes causes problems some of the major buildings the newer buildings well I call this nor this is the plots of Valentini have problems with sometimes there's subsidence compression of the debris and they get tilting and they have to fix things up there's the Trajan's column on the right talk about that a little bit but the the major example is near the the pyramid and that's the Monte Testatio and it's close to what was an industrial area in ancient Rome and a dock docking area for boats coming up the Tiber and bringing wine and oil in amphora amphora singular and used and then the broken ones tossed away the the this rather tall hill is made up of broken mostly broken amphora 53 million of them it's pretty spectacular today the mountain is surrounded or the hill is surrounded by nightclubs and restaurants another major problem with Rome or earthquakes maybe not so much of a problem if you built properly and most of the earthquakes occur within the avanines themselves and not too many earthquakes under Rome itself but still the effects are pretty great and if you look at this map of damage to various historical structures through time you can see that there's a lot of what I want to point out is that you know what these structures are built on quote often it's not so much the structure it's the underlying alluvium or rock or whatever the Colosseum you notice most almost people don't notice sorry but the Colosseum on one side is beautifully preserved the other side is a mess and the reason is not so much that it was quarried by people looking for a building stone but by the fact that the line between the undisturbed and the disturbed part of the structure is right over the boundary between Pleistocene sedimentary rocks you know and solidated sediments there was a lake there in this valley before the Colosseum was built and so it's a matter of what you build on not so much how big the earthquake is I won't go through this because Jean-Luc is going to talk about this in session three it's essentially looking at the columns and the difference between one that's on solid and material one that's on sediments of the Tiber won't talk about that the Vatican this is a map of the Vatican and most of it's on good solid ground and hasn't suffered much in the way of damage due to earthquakes or anything like that but out in front in the piazza were those beautiful oval piazza with the columns on all sides originally it was supposed to have been flanked by two large Campanile bell towers but because they were on the alluvium of the Tiber they kept tilting and finally they tore them down and Bernini designed the piazza that you see today the large thick monographs of the geology the aroma had been put into by Renato and Guido Giordano into a disc that you can get I think still which shows the geology of the in the front you have some some putti surveying you're right okay just a sample of the geologic maps in that and the as a geologist it's appropriate that urban geology which is a subset of geology a lot of it in Canada some in the U.S. some of it elsewhere that comes from herbs which is the ancient name for the city of Rome and we'll get back to the front where there's Renato Funicello on the left me in the middle and Panatella Derrita after my term there on my sabbatical we wrote a book called The Seven Hills of Rome and a year or two later with Maurizio Perotto Isetticole which actually in Italy won a literary prize can you believe that for a geology book so anyhow thank you Renato the late Renato Funicello and for introducing me to a remarkable time in my life bye thank you so much Grant for this presentation let me stop the chair hang on you know you have yeah I'm trying to just to know it's a I know that there is actually a student in Greece in who is who are watching your presentation and some weeks ago they were in Roma learning in Erasmus plus Roma and Geology of Roma so it's unbelievable for for them to to have a lecture today after their travel in Roma and so they are completely completely it's fine for them to to have these two things in a in a few in a few time period so thank you for them and thank you for all the teacher there I think they they learned a lot about the city of Rome as you said there there will be a hands-on activity about the the column of Marco Reilius and Tryan colon and earthquakes of course but maybe if some teacher have question to grant please you are welcome to to ask your question so I apologize there's a lot more to talk about but I only had 30 minutes I know it's okay it's okay you are on time it's okay so if you have some question is it's it's nice but I look in the chat if there is something check the chat check the chat yeah grant I have a I have a question you have seen we have seen a map with fruit I don't remember when exactly and if and we see in gray the the area with the fruit so that means that this this area is the bed of the Tiber river or that means that in this gray area is alluvial deposit only in Roma yeah the the the gray area I think was mostly just alluvium from the Tiber which as as sea level rose the Tiber started really doing some serious deposition because the channels there were very deep at the when the sea level was lowest and it's not terribly solid there is a building I can't remember the name it's a major government facility along the banks of the Tiber and they keep having to repair it because it's on alluvium and a lot of the columns keep falling over so it's it's a matter of the Romans themselves they they built in great places and they rarely built on the Tiber flood plane because of the floods yeah and at that time most of the the sites down there were for you know military training and things like that which if it flooded it was like so what so anyhow okay so I cannot see more question I have one more but it was about the earthquake we know that there were a lot of earthquakes in the second century or after the imperial period but how we know this we have archive or just looking at the monument or things like that actually there are archives or in the case of of the Coliseum there was damage and then it was rebuilt and there's a plaque in the Coliseum that refers to an earthquake that caused the damage and to the the gentleman who paid for the their restoration okay so we we collected that we collect information like this by this kind of event there's there's translations of oh what's his name uh the famous Roman engineer in the Vitruvius I think that's right and he wrote everything including a very detailed accounts on how to build a road but uh he his book I have it here in translation somewhere uh was just phenomenal for the time because he described uh but he described not the the earthquake he described the restoration yeah yeah yeah okay fine so once more again uh thanks very much Ron for this presentation I think it was uh very appreciated by our teacher so I have some uh I can see in the chat uh but the presentation was very clear so thank you very much you're welcome and now I think we have Matjou uh from Saskatchewan so from Canada so I think Matjou is with us I think so Matjou yeah hello I'm yeah hello hello Matjou hello it's the morning for you I guess right yeah and we we are going to to finish your first session of gift with you so you are from University of Saskatchewan right and you want to talk about climate uh social impact of some volcano or some volcanic period right yes so Matjou uh I'm I'm happy to welcome you and uh so let's go to to representation I think you can share your screen because uh I have done that and we we hear you we are going to hear you very uh very soon good can you see my title slide now yeah we can see you can yes we can see a volcano we've uh eruptive yes yes okay great so um let me also start my timer because it's always helpful for me to be able to see yeah thanks very much um it's a pleasure uh to be taking part in this I think it's a really great idea um to be to be sharing knowledge with uh with teachers and educators um my my parents were both teachers and educators um and uh have a lot of conversations about education I just think it's great to be uh to be connecting you know some some cutting-edge science what's happening now in the world of science with with teachers and see that knowledge transferred down to the to the next generation um I'm going to be talking today about um as was just said about uh climatic and societal impacts of um particular volcanic events um in the middle ages um and this is really an example of of um interdisciplinary research so my background is in physics I'm in the department of physics and engineering physics at the University of Saskatchewan I studied atmospheric physics so um the rate of transfer and the composition of the stratosphere um and through this project I got to do some really fun science uh taking some of my expertise and applying it to a problem that can only be applied or only be attacked in the interdisciplinary way so it got me to to to interact and work with historians and people who drill ice cores and reconstruct past climate and anyways I'll get into it and and and we'll see how that works along the way so the start of this story um comes to us from documentary evidence um so so things that were written down uh about what was happening in the year 536 so this is um uh I'm not a historian but uh and from what I understand this is the the Roman Empire um had had reached its height and then was in some sort of decline um a slow decline and um sometimes the Roman Empire would would get organized and have a little bit of advance but generally things were declining and then in the year 536 weird stuff started to happen and one of those things um was was documented by a number of observers throughout Europe so written down and we can you can read what they wrote down about this year um so things like this the sun gave forth its light without brightness like the moon during this whole year and it seemed exceedingly like the sun in eclipse for the beams that shed were nor such as it is accustomed to shed uh another observer Zacharias of my Tluné I don't probably not um pronouncing that right but uh he was writing down he was in Constantinople at the time and he wrote the sun began to be darkened by day and the moon by night from the 24th of March and this year until the 24th of June and the following year uh another observer uh wrote down that the sun was dark and its darkness lasted for 18 months each day had shone for about four hours and still this light was but a feeble shadow and then we get to the most important part the fruits did not ripen and the wine tasted like sour grapes so here we have like and again these are just a couple of examples but we have um uh clear evidence that something was going on with the sunlight it wasn't as tense as usual um so that's a huge key bit of evidence for us um but it turns out there was a number of other things going on at the time so if you look through different documentary evidence from different parts of the world this seems like a very important time in in history for a number of reasons there was famines widespread so um documentary evidence in Ireland of a failure of bread um there's evidence of cold and heavy snowfalls in Baghdad China reports of summer frosts and snow widespread famine um yeah crop failures and famines in the Mediterranean and then to top it all off a few years later and in the year 541 CE is when the first plague pandemic started in Europe um in Scandinavia there are no written records but there is um archaeological evidence that's uh points to huge changes in the mid 500s or 6th century um abandoned settlements uh decrease in agriculture um and the sacrificial gold offerings where people now find cords of gold that were buried around this time uh seemingly as some sort of um sacrifice to the gods um to to improve the situation and so there's some idea that this is connected to all of these climatic um instances that we're seeing around this time and so a lot of this is um um all summarized in a in a book by David Keys which is very interesting to read um he probably extrapolates a little bit further than what most scientists would but there's a lot of interesting things um in world history going on at this time um and so the question becomes could this be connected to what we just talked about the the decrease in the intensity of sunlight that was noted by some observers so let's look into physical evidence so um the natural sciences um can we can we get anything from that you might be familiar with the idea of um that tree rings are a reporter of climatic conditions so if you look at the um the width of a tree ring so every every year every summer a tree builds a ring and the width of that ring gives you um information about the growing conditions for the tree which in some locations and for some trees is very tightly correlated with the temperature during the growing season so if you pick the right trees in the right locations look at the width of those tree rings over time and count them back since the tree puts down a ring for every year you can count back in time and have very good time resolution and then use the width of the tree ring as a measure of of the temperature and so if you do that with um in this case this is from a study in 2008 where they looked at um seven different locations in Europe and averaged them all together uh put together a time series that looks like this and so this is a sort of proxy for temperature so um larger values mean warm temperatures and colder or negative values mean cold temperatures um and you'll see that the largest deviation from sort of mean conditions happens right around here in the middle of the sixth century and so if we zoom in on that um that time period what we see is a very sharp decrease in temperature in the year 536 and then a long duration negative value so over a decade of colder than than normal temperatures and so this is really um common in in tree ring time series that go back this far and fine so you can there's a number of papers that have noted this um and and very much the strongest temperature deviation um that that comes out of these of these proxy records um as an aside um you'll see some other cold temperatures uh that happen in later in the time series um and those happen to be associated we know with volcanic eruption so there was a an eruption of Hojana Petina in the year 1600 and you see very cold temperatures um represented in this in this temperature time series and the eruption of Tambora in 1815 also shows up quite strongly in this time series Tambora famous um for creating what has been called the year without a summer in 1816 in Europe um where the conditions were cold and rainy especially in in Switzerland leading to the um famines and um deaths of many people so here let's summarize with two main questions that come up to this point um so first of all what caused this mystery cloud in 536 that diminished the the intensity of sunlight and secondly was that cloud responsible for the climate and societal downturn that's apparent in um both documentary and archaeological evidence throughout the northern hemisphere so as I just noted um we do see these temperature decreases um associated with with volcanic eruptions so if we're looking at this um the situation volcanic eruptions have to be sort of our prime suspect here um there are other possibilities um a meteor impact um or our asteroid impact a comet um these these ideas have been put forth in the past um and for a long time it was hard to attribute um this event to a volcanic eruption but only just in the last few years has that been um convincingly done and I'll get into that but first I want to talk just a couple of minutes about volcanic eruptions and why um they might be the prime suspect for for explaining what was going on in this situation so volcanic eruptions as you know they erupt and put lots of material into the atmosphere um you see these gigantic clouds most of that is ash so bits of of rock uh in very small amounts that come out of the atmosphere relatively quickly there's a lot of water vapor as well um but from a climatic um um perspective the most important thing that's released by volcanic eruptions is sulfur and so that comes in the form of sulfur dioxide SO2 and it turns out that if the eruption is so large that the eruption plume reaches into the stratosphere then that has a very strong impact on climate what happens is that SO2 gets oxidized and turns into sulfuric acid and sulfuric acid will condense into tiny little particles what we call aerosols and and those particles again little liquid drops but tiny like um on the order of um microbes so um 10 10 to the minus six meters right like so really really small um and they spread out through the atmosphere and um they are good at scattering uh radiation so the incoming light from the from the sun is scattered some of that gets scattered back into space um so that decreases the amount of radiation that reaches the surface of the earth and that can lead to a cooling of the surface uh those aerosol particles also absorb long wave radiation which is emitted from the earth and so that leads to a warming of the stratosphere where those particles are so eventually those particles will be transported through the atmosphere and they'll they'll come down back into the troposphere the lower part of the atmosphere um where they will be um scavenged the the aerosol particles will grow because there's a lot of water vapor in the in the troposphere and they'll get deposited to the surface some of that will be deposited to the ice sheets of greenland and Antarctica and so then as ice is always being formed as new snow falls in um in those ice sheets um that sulfur will be still present in that ice sheet and so when scientists go and drill these ice cores um and and um drill a long ice core that's basically going back in time as you go through each layer of the ice you'll find a spike in sulfur um that's associated with these past volcanic eruptions so let's talk just a little bit about about the um the impacts of those sulfur particles in the stratosphere um I want to give you just a tiny taste of um atmospheric physics here or or climate physics to be more um precise um the the um the earth is heated through the absorption of sunlight right that's the only um or the the most important way that the earth maintains the temperature that's above that of other planets like like Mars right um sorry that's how the earth is heated is the absorption of sunlight um so if you imagine you have incoming sunlight coming in warming the earth then you have an radiation that's emitted by the earth that goes out to space um and in a steady state we expect that the radiation collected by the earth is equal to the rate of power emitted by the earth so if I write a couple of equations we can say here here's our that statement written down mathematically um the incoming rate of power which we call shortwave radiation from the sun is equal to the outgoing longwave radiation uh emitted from the earth we can now write these things down a little bit more concretely if s0 is the um um flux coming from the sun um and it's being absorbed by an area um pi r squared where r is the radius of the earth um and then we have this factor of alpha which is the albedo of the earth I should go down so we have a couple of things oh and I have a typo this should be alpha down here I changed my my variable terms so this planetary albedo which I call alpha up here is um tells you the amount of radiation which is just immediately reflected back into space due to clouds due to ice things like that so that that's the amount that's not absorbed by the earth good and then on the right hand side we have terms which are related to the temperature of the earth so the warmer the earth is the more radiation it emits to space um and it turns out that we know that this relationship goes as the fourth power of the temperature of the earth um and that's emitted by the entire surface area of the earth anyways we can take these equations now and simplify them a little bit and solve for this effective temperature of the earth and we get this relationship here so we can see that this temperature this effective temperature of the earth is related to really only two things s zero which is the amount of radiation coming from the sun and this term alpha the albedo so that's really key if we change this alpha the albedo of the earth the amount that's reflected then that leads to a change in the temperature and so you can use this very very simple relationship to calculate that for example a one percent change in the albedo would lead to a temperature change of the earth of around zero point three degrees celsius so as an example look like um a sort of visual example imagine that for some reason the earth just becomes a little hazy the atmosphere right you have more of these aerosol particles oops it comes a little hazy and from space if you're looking at the earth it would become a little bit brighter and so that means that more radiation is being reflected from the um from the earth and so then less is being absorbed at the surface and the surface temperature would go down great okay so how do we know that volcanic eruptions really are are important for climate um so our most recent example of a very large eruption which had this kind of impact on climate um was in 1991 the eruption of mountain it you go um and i wrote down a few numbers associated with this eruption because i find them quite um impressive so this eruption ejected 10 cubic kilometers of material out of the earth into the atmosphere it's a huge volume of material the column height um of that that plume reached 25 kilometers so well into the stratosphere and the emissions the gas emissions from that um eruption we have a very large amount of water vapor carbon dioxide as well as sulfur dioxide and some other other species it turns out that this amount of water vapor and carbon dioxide are pretty negligible compared to the amount that's already in the atmosphere um yeah just to put some some units on here so these are all listed in teragrams um and one teragram is equal to a billion kilograms or in other words a million metric times so these are really large masses of gases put into the atmosphere from the eruption so as i said the amount of water vapor and CO2 is pretty negligible compared to the amount that's already in the atmosphere but this amount of SO2 sulfur dioxide is quite significant it works out to be about 10 to 20 percent of the modern global annual anthropogenic SO2 emissions so what we're putting out because of pollution um but most importantly um about this eruption is so that's a lot fairly large amount of SO2 but the fact that it gets into the stratosphere um really is important for this climate impact and the reason for that which i've alluded to earlier is that the stratosphere compared to the troposphere is extremely dry so this plot is showing you um both the temperature um as a function of height above the surface so the temperature is in these kind of dotted lines and you see that the troposphere the temperature decreases with height um until you reach a minimum at the tropopause here and then it's relatively constant it'll actually start to increase a little bit with height as you get into the stratosphere that's what defines the troposphere versus stratosphere um but because of that the water vapor mixing ratio changes quite dramatically as well um i'm going to get my laser pointer here this helps a little bit um so you see that in the in the black solid line here we have the profile of water vapor as a function of height above surface it's also decreasing with height but this is the log scale in the bottom so we're seeing orders of magnitude difference in water vapor mixing ratio as we go from the the surface of the earth into the stratosphere and that's important in our in our case because these little sulfate aerosol or sulfuric acid aerosol particles that form in the stratosphere from the sulfur pudding by the volcanic eruption if they were in the troposphere whereas very wet they would just grow water would condense onto the particles they would grow larger and then they would have a gravitational setting velocity that would just pull them down to the to the ground but in the stratosphere they stay small and so they're able to float within the stratosphere for a very long time good so what's shown here now is um temperature of the lower troposphere so um um measurements from satellites of the um temperature of the first couple of kilometers of the the troposphere down where we where we live um from around 1980 to 2012 or something like that so concentrate on the blue and red lines here you'll see that that temperature kind of fluctuates from year to year sometimes it gets a little warmer sometimes it's a little bit colder um but and we'd like to understand why it does those things is that just um um random variations or are some of them forced from um the result of something um it helps if we look at this time series if we um remove the effects of El Niño so you've probably may have heard of El Niño um temperature ocean temperatures in the Pacific kind of go up and down and so um cycle and this can really affect the global mean um surface temperature so but we can statistically kind of remove that from our time series um and then we see a time series that looks like this in the bottom and what we see here now quite a bit clearly is the impact of this volcanic eruption of Pinatubo in 1991 had on on global temperatures so we see a decrease here of around 0.8 degrees and this again this kind of average temperature the first couple of kilometers of of the troposphere there was also a fairly large eruption back in 1982 El Chichon in Mexico and we can see that it also had an impact on on temperatures if we go further back in time we see this effect as well so if we look at um proxy based temperature reconstructions of the temperature of the last millennium here so that's on the bottom panel I'm showing here and these proxy based temperature reconstructions are in this sort of gray shading so you have a lot of different proxies and they give you different information so you build a bit of a um a range a likelihood range of what temperature was like as we go back in the past so this is a northern hemisphere mean so we're just kind of averaging the temperature over the full northern hemisphere um and looking at it as a function of time as we go back in time so if you follow just this gray shading you see that there was colder periods and cold decades and then if we go back in time further into the Middle East times things seemed like they were a little bit warmer and it turns out that a lot of these cold periods and especially the cold years and cold decades line up very nicely with when we think there were these large volcanic eruptions in the past so on the top here we have an estimate of volcanic um radiative forcing um from from archives that um record the timing and magnitude of past volcanic eruptions and so you'll see these periods again here this is um this Tambora eruption in 1815 and a couple of other strong eruptions that happened around similar time period and you can see the impact that that had on on temperatures I should mention uh that the red and blue lines in the bottom plot come from climate model simulations which use this time series of volcanic forcing um and that those simulations then produce fairly good agreement with the proxy based temperature reconstructions which are in that it's in the gray shading so I talked a little bit about these volcanic eruptions in climate and and I tried to say that it's kind of a prime suspect for what happened in the year 536 um so usually how these how we have information about past volcanic eruptions come from ice cores I mentioned so as the scientists go to to Greenland or Antarctica and they drill these ice cores into the into the ice and then they can do a sort of chemical analysis along the length of the ice um and get a sense of of what was in the atmosphere as we go back in time and a particular year in the past um and if then if you do analysis and look for sulfur along the length of an ice core you will get time series that might look like this along a top plot here and you'll see again these spikes in sulfur amount in the ice core um and these turn out to be predominantly because of past volcanic eruptions okay um and so if we look at time series for both Greenland and Antarctica so on the top is a time series from from Greenland on the very bottom here we have a time series from Antarctica sometimes we find peaks that line up very well between both hemispheres so Greenland and Antarctica both have a spike in their sulfate in the around the year 574 or 575 so this is evidence of a volcanic eruption that happened in the tropics so in a low latitude and the sulfur was able to spread throughout the whole globe and then be deposited both um in in both hemispheres in Greenland and Antarctica um in other cases you'll find a spike just in one of the two hemispheres so here we find a spike in year 536 in the Greenland ice cores but no corresponding spike in Antarctica so this is evidence of an eruption that happened in the northern hemisphere and its sulfate aerosols were mostly contained within the within the northern hemisphere um right so here um I should kind of mention this study was was monumental in year 2015 because it corrected a dating error um that had been in the ice cores for for decades um up to this point and so it was the first time that these time series all got shifted by a few years and so it was the first time that we were able to see uh these sulfur peaks in the ice cores line up exactly in time with the tree ring anomalies the sort of proxy for surface temperature um which is shown in the middle panel here so here's some um tree ring growth anomalies that have this very um strong negative um anomaly in the year 536 and then for decades afterwards and so here for the first time we were really able to prove uh that the that these um temperature anomalies could be connected to volcanic eruptions and particularly two volcanic eruptions one in the year 536 which was probably northern hemisphere since its signal shows up only in Greenland um and then a second eruption that happened in 540 where its sulfur is found in both Antarctica and Greenland giving us evidence of a tropical eruption like I said that spreads its sulfur um throughout the globe and then another eruption a couple of decades later in 574 or 575 so so that's the um basically the standpoint now that we really we know that it was a volcanic eruption that happened around this time so this um uh almost definitely explains the the diminishment of sunlight that observers wrote about in year 536 um but it's asking the question of whether that um eruption and and the sulfur cloud um was responsible for the climate and societal downturns that we saw in the northern hemisphere is a little bit trickier right it seems likely but how do we prove it um and especially a more subtle question is some historians and others have looked at the records especially in the Mediterranean that mentioned the 536 mystery cloud and this author suggests that from from what they were able to read they saw that this mystery cloud was connected to bad harvests for one or two years and people treat it as like a temporary bad omen but not the beginning of a long period of unbearable climatic conditions you know so it didn't seem like any clear crisis in the Mediterranean so so how do we make sense of this where it was you know observable but not a big deal on the Mediterranean but seems like in other locations um it was a crisis that might have you know had a wiped out or or considerably um okay so so here's the situation um I'm running a little short on time because I've talked too much but we have a number of different evidence from a number of different fields right we have ice core records of volcanic eruptions in the years 536 540 we have tree rings showing cooling in this period we also have the contemporary chronicles that talked about the diminishment of sunlight and we have archaeological evidence of population decline and other things particularly in Scandinavia is one place where this seems particularly strong but other locations as well so how do we bring these things all together and try and get a sense to this how much this event really impacted the climate and societies well what we're what we're going to do is use climate models use representations of the atmosphere and climate to kind of bring these things together in particular we're going to use the ice cores and the chronicles to get a sense of the volcanic forcing the amount of aerosol in the stratosphere and its impact on radiation then we'll use that in the climate model to estimate the climatic response so changes in temperature and so forth and then use that to try and understand how that might have impacted societies so what is a climate model so in general scientists use models to represent um empirical objects the world around us phenomenon um using physical processes in a logical and objective way so that means particularly or in many cases using a little bit of math right and it's important to know that models are a simplified reflection of reality that despite a number of approximations can be extremely useful for understanding the the thing that you're that you're modeling the thing that you're trying to understand so you've actually met a climate model already that's the couple of lines of math that i introduced earlier which gave us a an idea of the effective temperature of the earth as a function of the incoming solar radiation and this albedo right so this is extremely simple we've made a huge amount of assumptions including the fact that it does not include an atmosphere at all which is really really important but it still was a little useful for us because we got an order of magnitude estimate of how the surface temperature or the temperature of the earth would change for a small change in albedo so that it's useful even though it's simple um what what i'll be talking about more here what is now kind of called comprehensive climate models which are are generally large computer programs that simulate the movement of mass and energy throughout the earth system so that's the atmosphere but also the ocean and land surface and even other things so these again huge computer codes run on some of the world's fastest supercomputers and they're used in these climate change projections so the to get a sense of where climate will go in the in the future right so the first model i'm using is an aerosol is a model of the stratospheric aerosol itself the physics of how those aerosol particles form and how they're spread out through the atmosphere and so i'll give you just a video of how that looks if you run a simulation like that so here's a simulation of an eruption in the central america the plot is showing you aerosol optical depth so how much light is being attenuated as it makes its way through the atmosphere because of those aerosol particles and you can see how the particles are being transported around the globe they stay within the tropics for a good amount of time but then start to be transported into the extra tropics particularly into the northern hemisphere in these first few months of this simulation eventually they'll start to come into the southern hemisphere as well right so so by running that kind of simulation we can get a sense of how much light is being attenuated by these aerosol particles as a function both of space on the globe and time and for to run those kind of simulations we just need estimates of how large the volcanic eruption was and where it was we can get estimates of how large the eruption was based on the amount of sulfur that we find in the in the ice course um and so based on some just uh some little scaling functions we can estimate the amount of sulfur um sulfur dioxide injected by these eruptions so for the two eruptions one five thirty six and one five forty um and then from the um the amount the relative amount in greenland and Antarctica we can get a kind of rough sense of where those eruptions may have been um which is useful for our simulations so one other important point here was that um the like I was saying the height of the eruption plume is very important and we did some simulations with this model um because one of the things that was that's really phenomenal about this about this eruption seems to be this fact that the the light was diminished for up to 18 months right we saw that inside of the the documentary evidence that was written down and that is really phenomenal and what we found by doing some simulations was that that's really only possible if that eruption plume is really high in the atmosphere so if we inject the our sulfur to 23 kilometers which is the blue line here we find that the diminishment of sunlight lasts considerably longer than if the eruption was at for example 18 or 15 kilometers um so here we were able actually to use that documentary evidence to give us information about the height of the plume in the atmosphere so we we we use 23 kilometers for our injection height the latitudes and the amounts that I talked about before and ran simulations to get a feeling of for the aerosol up to the depth producing a plot that looks like this and so what you'll see is that what's particularly um coming out or or evidence about these eruptions is that the the forcing the amount of aerosol was heavily concentrated in the northern hemisphere for both the 536 and 540 eruptions which perhaps helps to explain their strong impact in the northern hemisphere let's get over that for a second um the next step then is to use that information in a comprehensive climate model again one that includes the atmosphere and ocean and a number of other important parts of the climate system or earth system and then use that information that we've gleaned from the aerosol model into the full climate model and when we do that then this is a a plot of the results where we're showing the northern hemisphere mean temperature anomaly so the how much temperature has been changed because of this series of two volcanic eruptions and we see hemispheric mean temperature anomalies that reach up to two degrees celsius after the 540 eruption which is a huge amount compared to the natural variability of of of the earth right this is extremely cold and so on the bottom here now are maps showing how that those temperature changes are distributed over the over the globe and we see in summer northern hemisphere of summer we see a concentration of these cold temperatures in sort of the 40 to 45 degree north latitude range so that actually includes the Mediterranean but we also see strong temperature changes up in northern northern europe in winter this situation is fairly similar although now the temperature anomalies are really concentrated over the high latitudes especially over regions where we have ice sheets normally or sea ice we can compare the simulated temperature anomalies with what we see in the tree rings the proxy reconstructions and actually these comparisons turn out to be extremely nice especially for the 536 eruption so you notice on these plots now the simulations are in gray and the tree ring temperature time series are in blue and you'll see in a number of places perfect agreement for the 536 eruption some places it's a little bit further off which can happen there's uncertainties in both the in the tree ring reconstructions and obviously in our forcing as well but these this agreement is extremely encouraging you'll notice that there is some disagreement between the simulations and the tree rings as we get into the later time period here our simulations seem to return back to normal conditions a little bit faster than the tree rings and so this is a still an open question exactly what's going on here is our model missing something that might actually prolong the impact of the eruptions so this is still still an open question the last part of the puzzle here and I'll have to try and really be quick is to try and connect these things to to society right and so we've taken I think just a small step but an important step in trying to do that and so what we could do is a use use our simulations to calculate something that's more connected to to agriculture and cultivation and so the first step in doing that is to calculate something called a growing degree day so that you basically just take your temperature time series to even daily mean temperatures and sum them up so there's a number of crops that you just need a certain amount of heat over a growing season in order to make a particular crop or to grow to fruition right so if the temperatures were too cold to the pulling through the growing season you wouldn't be able to that crop whether it's wheat or barley or something like that wouldn't get enough heat during the growing season in order to produce its its seeds and so this can be connected to something called a cultivation suitability index which just basically tells you gives you an idea of how how well an area is suited for cultivating crops based on its temperature so when we applied this concept to our simulations what we found is that the change in this cultivating cultivation suitability index was really concentrated in a particular latitude range right around Scandinavia so right where we have this archaeological evidence of sacrificial gold offerings and changes in settlement and so so forth which are kind of indicated by these colorful dots and the locations where those things have been found they happen right where we find this large change in this cultivation suitability index and what's probably most important is because we have these two eruptions closely spaced in time in 4.536 and 540 we'd have potentially a number of years with very strong changes in this cultivation suitability index so in some locations up to four years where the this index would would be significantly decreased so I think this is we're trying to connect it to a societal aspect which is you know people could probably deal with one bad harvest one year of bad harvest you might have some reserves you have livestock which you can which can get you through but if you have two three four years of bad harvest this is going to be extremely hard on people and this also tells us potentially a little bit about why they did not notice such drastic crises in the Mediterranean because the change in the cultivation suitability index was potentially was there but it was small and you didn't have this multiple years of changes in cultivation whereas in the northern most further north in Europe you did have large changes so this is just one example of collaborative work investigating these eruptions and and ongoing work is looking at lots of different aspects of this and especially a lot of that is connected to this working group called volcanic impact on climate and society so quickly a couple of conclusions so we reconstructed a plausible eruption and radiative forcing history for these eruptions based on natural archives but also quantitative documentary data which was extremely useful in this case we ran climate model simulations which showed maximum northern hemisphere mean temperature anomalies of about minus two degrees and showed a really good agreement with the available truing reconstructions and we've like I said taken a step to try and interpret those climate model results in terms of their impact on societies where we can see we think good evidence for multiple years of crop failure in Scandinavia and minimal impact on agriculture and the Mediterranean so to learn more I put here just a link this is all published in a paper from a few years ago there's going to be a number of talks later in this workshop I'm talking about volcanic eruptions and society which I'm really looking forward to and there's also we've been working within this working group VIX we've been putting together a special issue in the journal climate the past which collects a number of articles on different aspects that are related to what I've been talking about particularly one that's in under review at the moment which continues this conversation about the 536 and 540 volcanic event and particularly it's in background Scandinavian society so if you're interested in this I encourage you to to check out those this special issue in that article and in particular so with that I'll thank you for your attention sorry I've gone a little over time but nobody told me to shut up so I hope that's okay thanks very much thank you thank you Matthew it's okay for a presentation it's the reason why I said no thing it was so interesting thanks a lot maybe we can have some question from the from the teacher so you have a you have a question in the chat Matthew okay can you can you have a look okay let's see I saw I see one from okay so yeah yeah essentially said uh some question for you yeah so which kind of tree rings you have used yeah let me talk about the tree rings a little bit more yeah okay go back to the relevant slide so okay so good question question first from Hirashi is which tree rings have been used for this figure that's a good point I should have been more clear about this this is a collection of seven different locations throughout Europe so there's a few from from northern Scandinavia I think there's one from from the Alps that goes into here as well potentially kind of northern Russia but I'm not a hundred percent sure about that so definitely weighted to to Europe and and probably heavily weighted to northern Europe it turns out that that that a lot of treeing reconstructions you're looking for a place where the tree is where temperature is the limiting factor in the growth of the tree and so this tends to be on on the sort of edge of the temperature distribution of the tree so they tend to come from the sort of northern latitude a lot although sometimes that can happen if you're on a mountain and so you have trees that are right at the location where the temperature from year to year can be lower or higher and critical for the growth of that tree so that's I think my understanding of like why a lot of them come from the northern high northern latitudes or or from mountain regions um so it was it unrivaled in all over tree rings all over the world yeah some close another good question so um we would love to find out more information about 536 and its impact on the southern hemisphere unfortunately there are there's a limitation of tree rings in the southern hemisphere there's just not as many good locations to to um to get them um and and so I'm not aware at this point of any good evidence for its impact in in the southern hemisphere but we're hoping for more data on that to be coming up soon a lot of scientists are working on collecting more data in in northern hemisphere but it definitely in north america we do see this as well okay one more question here I see from um how have you calculated the z score yeah so a good question what is the z score it's a little bit weird so it's not exactly temperature I've talked about it as if it's temperature but it's kind of a proxy for temperature proxy yeah yeah so the z score is basically just a statistical thing that's like um it's like the standard deviation multiples of the standard deviation so if you have a long time series and it goes up and down you can calculate a mean of course but you can also calculate a standard deviation and so then if you divide your time series by the standard deviation what you get is the z score so if a value is two it means that it's two standard deviations away from the mean value so it kind of shows you like how common it is or how unlikely so um a value of two is pretty unlikely it doesn't happen that often so you can see that it only happens in a couple cases in this whole time series uh here in 540 or so and then in 1600 as well so it just just means that it's unusually cold in that year okay Matthew thank you thank you for your your great lecture it was uh the comments of the teacher so uh I leave you to appreciate the chat thank you so much uh for uh everyone it is the end of the our first session I hope you you like this one and uh but you will be able to to join us for tomorrow tomorrow it will be tomorrow morning in uh in Europe so um be online uh on time uh just if you uh if you don't see if you're not if you are not able who are available for all the session you know that we are very for us it's very important to to have a evaluation from the teacher so at the end of the gift you will have to complete the evaluation form so I give you in the chat the link to complete the evaluation form at the end of the gift but maybe you will be with us only today so I give you the the link to complete the the evaluation form only at the end of the gift so that means Friday I would like to thanks again Matthew from the the presentation and all the lecturer so so Grant and Ray for all this afternoon very interesting and with some different topics so I think the the topic of the impact of geology on the society is open now and tomorrow and until Friday we will go ahead with more lecture and more hands-on activity so to everyone bye-bye see you maybe tomorrow and the day after have a nice uh evening for European people have a nice day for for the other one and thanks again for the lecturer and bye-bye see you soon for the next time bye