 Good afternoon everyone. Give me a thumbs up there Andrew if you can hear me so we know we're okay great. Welcome everybody. Thank you for joining us for what I think will prove to be a very interesting session. This is a webinar put on by the Committee on Geological and Geotechnical Engineering, which is a part of the National Academies of Science and Engineering and Medicine Board of Earth Sciences and Resources. It's a very active committee looking for ways to help define challenges for us in the geotechnical arena. And it was a committee that was established to be the focal point within the academies for technical and public policy issues related to earth processes and materials, soil and rock mechanics, and the mitigation of natural and human hazards, along with responsible human development in these subject areas. As we go through this if you have questions write them down there is an opportunity for you to enter them on a question entry point. Down, I think it's at the bottom of the screen, and we will screen through those and time permitting we will ask as many of those questions as we can we usually have more than we can get to so we apologize if, if we don't get to your question but we'll do the best we can. This webinar will be promoted posted on YouTube, an announcement will be sent to all of you who are attending today, as to when you can see that and where to get to it. I'd like to thank Samantha Massino, Alene George's and Eric Edkin, who are the folks that at the National Research Council who help us with all this and do a great job of organizing and producing these webinars. Professor Pedro Arduino from the University of Washington is another Coggy member and he is going to field our questions today. This is a challenging job because we get many questions and trying to organize them in a way that we keep flow is good. Pedro does a great job of that. Again, you can submit your questions anytime. And he will try to get to them as we as time permits. I do have to read a disclaimer here that's required by the Academy that any opinions conclusions or recommendations expressed by Dr. Whittle or anyone else during this webinar are those of those individuals and do not represent conclusions or recommendations of the National Academies of Science, Engineering or Medicine. They're very, very careful about not getting involved in controversial issues. So with all that, I'd like my great pleasure now to introduce Professor Whittle, who I've known for quite a few years. He's Edmund K. Turner Professor of Civil Environmental Engineering at MIT. He's known as an expert in geotechnical engineering, where his research deals principally with constitutive models of complex mechanical properties of soils and their application to predicting the performance of foundations and underground construction projects. His research has been widely used in the design of foundation systems for such facilities as deep water, oil production, major urban excavation and tunneling projects and other similar endeavors. Most recently, he led research efforts in the application of wireless sensor networks for monitoring underground water distribution systems and construction projects. He's a licensed professional engineer and a very active consultant and many major projects. He earned his BS degree from Imperial College in 1981. His doctor of science degree in geotechnical engineering from MIT in 1987. He's published more than 240 papers and received several awards for his work from the ASCE. In 2010, Dr. Whittle was elected to the National Academy of Engineering, which is a very prestigious honor, well deserved. Professor Whittle, please proceed with your presentation, which is called Responding to Climate Change through Geotechnical Engineering Research. Thank you, Alan, and good afternoon everyone. It's my pleasure to be here this afternoon with you. I'd like to begin by just thanking the committee, this Geological and Geotechnical Engineering Committee of National Academies, for the kind invitation for me to present to you today. They gave me this challenge. They said, how should Geotechnical Engineering Research respond to climate change, the challenges of climate change. As you can imagine, this is a huge topic to cover in a relatively short session today. I should say I've given quite a lot of thought to the future of Geotechnical Engineering Research in particular. And we'll reference a paper that was co-authored with Patricia Colligan and Jim Mitchell, and I think is on the link for the advert for this webinar. So a lot of the stuff on the actual scope of Geotechnical Engineering Research is in that area. But what you're going to hear about today involves a sort of fresh perspective on where climate change fits relative to this. I want to begin with some key definitions. The first thing to appreciate is what is climate change. And climate change is caused by the production of greenhouse gases, the trapping of heat in the atmosphere. And that's generated the increase in the greenhouse gases is generated principally by human activities. I think you're all aware that over the last five years we've had some of the hottest years in recorded human history. And over in 2000, coined the term Anthropocene epoch. And I think it's kind of appropriate for a committee on geological and geotechnical engineering to start by acknowledging the term. It essentially says that humans control an awful lot of the environment of the planet moment, and probably since the starting of the industrial era. There are some other terminology from climate change we really need to understand before we embark on this. The first thing is that mitigation in the context of climate change refers to a general strategy to control global temperatures through reduction in greenhouse gas emissions. It's as simple as that that is the main purpose of mitigation. In contrast, adaptation adaptation refers to all the many, many policies and actions to reduce vulnerability and impacts on human populations at all scales from the very local to the very global. So adaptations are much more complex myriad set of tasks, I would say. There are other terms that have been used in the context of climate change and it's worth just mentioning them in passing, although I'm going to say little about them. The term introduced in 1987 by the Bruntman Commission, which talks about meeting the needs of the present generation without compromising the ability of future generations to meet their needs. In preparing this talk I found it really interesting because in 1987 I was finishing my PhD thesis. And at that time, people were really concerned about running out of fossil fuels. Here we are 30 years later and our principal concern is somehow weaning ourselves off fossil fuels to other sources to control greenhouse gases. It's funny how the world turns. The other word you're going to hear a lot about I think is resilience. Resilience generally refers to the ability to anticipate, prepare for and respond to sources of stress on systems. That's what it means very broadly. In most engineering context, it refers to ensuring delivery of essential services. You may spare a thought in this pandemic for our colleagues in transit agencies who have discovered themselves in a rather unusual position, but suddenly there is no demand for public transportation and therefore there are no revenue streams for all of the activities they need to run their systems. So in fact, there are many people going through resilience testing right now as we speak. Let's think about mitigation. If you start on the mitigation topic, you realize you have to understand something about the balance of carbon or carbon dioxide in the atmosphere. You'll see there's a unit conversion down the bottom of this figure. The message I'm trying to give in this figure is there is a net atmospheric growth of carbon or carbon dioxide in the atmosphere through our activity through our industrial activity through our changes and land uses. Of course, some of the generation is handled by a sink in the terrestrial biosphere and a lot more of an uncertain amount perhaps going into the oceans where we may actually be acidifying the oceans very slowly. This of course doesn't tell us what's going to happen in the future. What's going to happen in the future depends very much the way the economy grows and the way we continue to produce greenhouse gases. The Intergovernmental Panel on Climate Change views this by talking about how we control CO2 equivalents in the atmosphere. And you can see on this figure on the right that there are what are called representative concentration pathways. And you'll see these on some of the future figures. 8.5 essentially is referred to as business as usual or growth prospectus as usual and greenhouse gas production as usual. And you can see the CO2 keeps growing. On the other hand, RCP 4.5 has this thing taper off by about 2080. And the most aggressive RCP 2.6 has a reduction back down below 400 parts per million. So this is the prognosis of the driver for everything that's going on globally. The other figure I think that I should bring to your attention very soon is energy consumption. This is a figure generated annually by Livermore Labs. And you can see it refers to US energy consumption. You can see in the pink you can see the users and on the left hand side you can see the sources. I should say from a personal perspective you probably start thinking transportation and energy for transportation. And of course we know that electric cars are coming along so we can visualize some changes in energy users for transportation. The biggest change in this figure over the last 15 years is in electricity generation. In fact, the US has reduced the amount of greenhouse gas produced in electricity generation by about 27% over the last 15 years. And that relates to the sources used the energy sources used as geological and geotechnical engineers we're very much involved in this map. In fact, we're very heavily connected to the production of fossil fuels petroleum coal natural gas. We also have a long standing connection to hydropower and pump storage. A unique connection to geothermal energy and of growing interest in wind energy so we're very well connected in all these different sources. If you were to ask what is the one thing that's really changed in this chart over the last 15 years, it would be the transition from coal to natural gas for electricity production. And that's really been enabled by hydraulic fracturing and direction drilling. So I could argue that the work of geological and geotechnical engineers has been the largest single shift so far in this picture. Of course shifting to natural gas doesn't wean us off fossil fuels. It's really a sort of transitional stage. And it points out that getting from reducing greenhouse gases across this chart is a multifaceted approach. And there are many sort of side paths on the way it's not a simple process. One has to conceive of doing a great many things. The other thing that's improved electricity generation of reductions is the advance of solar and wind and geotechnical engineers in particular been very involved in wind energy. If you look at electricity power generation across the US you'll realize it's very regionally dependent so what you see of electricity production depends on which part of the country you live in. For example in the northeast we have seen very clearly the switch to natural gas from coal, whereas in the south, the North Rockies and the upper Midwest, the presence of wind energy becomes very obvious. If you look in the bars here the little blue bar refers to the cost in cents per kilowatt hour, you'll realize why wind energy in those regions is being adopted very rapidly because it's costing less than 10 cents a kilowatt hour. On the northwest of course there's hydropower and so on so the perspective on power generation depends very much where you live, and how you see this transition. Geotechnical engineers have been very very engaged in offshore wind power, and the primary focus of this has been in the North Sea. If you look today in the North Sea there is something like 27 gigawatts of installed offshore wind power. It's nearly all in shallow waters under about 30 meters depth and involves fixed bottom platforms founded on monopiles. The cost, the component cost, the capital cost, the substructure represents almost 30% of all the costs of offshore wind farms, and therefore the foundation engineering plays a very big role in the development and the reduction of cost of offshore wind power. In the North Sea, the cost for offshore wind power around six cents a kilowatt hour, so already very competitive across the grid. As we move forward in time, these offshore wind turbines are becoming enormous. This is the latest from IEA, and it's a 15 megawatt turbine, it's got a rotor radius of 120 meters, that's almost 400 feet. So these are absolutely enormous structures. And as we install these enormous structures in deeper and deeper waters, ironically we're going to leverage more and more of the knowledge from the offshore oil and gas industry. So for example in the figure on the bottom left, you can see a large offshore wind turbine subject to loads, and I'm showing it on a bucket foundation or a suction case on, which is probably the most efficient type of foundation that might be used offshore in the US at least in the short term, in terms of supporting the loads. As we go into deeper waters we're going to need floating structures and anchorages are going to follow very much from the oil and gas industry. You may ask why North Sea first? The North Sea first is because the whole area around the North Sea has a very large population density, we're talking about 160 million people living in that map area. And as a result, offshore wind can serve a large population. But of course wind energy is intermittent, and therefore power storage becomes very critical. And the other very important element that's made the North Sea successful is the potential to interconnect through high voltage direct current lines, interconnect the grids of the different countries. This enables the UK to be connected to Norway. And there is an enormous storage potential in Norway with unmet pump storage for hydropower. So the North Sea has some natural advantages, which have really made it the place for offshore wind. If you turn to the US and you say what's happening, this is a map showing average wind speed at 80 meter height, and you'll realize the middle of the country has enormous onshore wind capacity. In fact, we've got more than 100 gigawatts installed in the US at the moment onshore, and about half of it in Kansas, Iowa, Oklahoma and Texas, and you can see that band at the middle of the country. But it's relatively far from the big population sentence. So offshore wind on the east coast has also got enormous potential from the wind speed as you can see, and has somewhat deeper water depths. The story so far is a little disappointing, because although there are huge projections on offshore wind projects in these areas, you can see from the bottom diagram on the right, that we're vastly under fulfilling our expectations. So we should have already installed almost the same amount of power as in the North Sea, and we're perhaps four or five years adrift in this. So the story is not always simple, but I can see how geotechnical engineers are going to lead this development in a very big way. Another very interesting area where geotechnical and geological engineers have played a role is what people euphemistically call shallow geothermal. So geothermal is a very strange term. The figure on the left shows how the ground temperature varies in the course of a given year, and you'll see a cone such that below about 10 meters and certainly blow about 15 meters depth in the ground, the temperature remains constant year out. And in fact, if you go deeper and deeper in the crust, there is a small thermal gradient. We can use the fact that the temperature in the ground is characteristically somewhere between 10 and 15 Celsius to help us with building heating and cooling. Ground source heat pumps were first developed in the 1940s in the US and became a very big target of opportunity from the 1970s onwards. Ground source heat pumps are essentially doing heating and cooling of buildings, and they can discharge excess heat into the ground. So in the summer months while we're killing a building we can discharge and store excess heat in the ground, and in winter when we are trying to heat buildings we can draw the heat back out of the ground. So we can manage seasonal heat storage through shallow geothermal. It's changed in the last 15 years. Well, obviously we would like to move from ground source heat pumps which are very efficient being used in residences into big industrial and commercial developments and geotechnical engineers have sort of seized the moment here, and they've blended heat exchanger elements into the foundation elements, and people talk about energy piles or underneath buildings or heat exchanges in piles. Okay, this is a fairly bold move because you're now combining structural function and heat exchange. But the development has been very successful and works very well in many northern hemisphere areas where the seasonal heat exchange is going to be important. It's also been interesting to see how heat exchanges have found their way into other varied infrastructure, for example in tunnel linings, there are several examples of projects which are now exchanging heat with a tunnel or subway station in the surrounding soil. There are also all kinds of sustainability possibilities here. I've been fascinated in parts of Europe where old mine workings and old shafts are being used for heat exchange by storing fluid in the mines and using the constant enthalpy of the fluid in the underground space. So there are many possibilities in this space. But geothermal generally means something bigger. It generally means something about the heat production inside the crust of the earth and the radioactive decay in igneous rocks in particular. You have to go much deeper in the ground to see real geothermal possibilities. The figure here shows us going down to perhaps eight kilometers. Most of you are aware that we get power from geothermal or hydrothermal plants, which produce essentially steam because of the very high temperature of the fluid. But the potential here for enhanced geothermal systems is really enormous because what it requires effectively is to find a depth in the ground where you have sufficient temperature to create a network of fractures and then essentially to use a carrier fluid to be able to transfer heat from one place to the injection point to the rejection point. Now what's fascinating about this is that the field hasn't moved very far. And the question is, with such enormous potential, why? And it seems to me that enhanced geothermal may be on the way in in a big way, because the binary power plants that can be used to generate electricity really only require fluid temperatures a little above 100 Celsius these days to be able to produce electricity as opposed to heat and cooling. So, where do we stand on this? Well, the maps at the top show you the maps of rock temperatures at two different depths. And you can see almost universally across the US, we have rocks, certainly at six and a half kilometers with more than adequate temperatures so we could be obtaining power from hot dry rocks through EGS systems. The beauty of this technology is it provides baseload electric power and therefore can replace many of the fossil fuel plants that are still in operation. It's almost universally available. The downsides to this, I personally am not sure that we've got any, we don't know. People ask questions about induced seismicity, but I've yet to see something which suggests significant problems. So it seems to me that enhanced geothermal may be back on the way in. Now of course this doesn't get us all the way to decarbonizing the economy. You will appreciate that to get from here to there is an enormous challenge. This figure shows greenhouse gas emissions in the equivalent gigatons of carbon dioxide per year. It's helpful to have in mind that we produce about 50 gigatons of carbon dioxide or equivalent per year at the moment. Trying to drive this down to zero is an enormous challenge. You can see in the red line, the projection which tries to do that in a time frame so that we keep changes in global temperatures less than two degrees Celsius. And it says we have to reach a condition of zero greenhouse gas emissions by about 2090. Now if you look at the individual government commitments you'd say fine we're in good shape. The commitments have committed to getting down there by about 2050 to 2060, but they're already behind in their projections, and certain parts of the economy are going to be very hard to decarbonize. So we're going to need negative co2 emissions we're going to need to get to a condition where we can store co2. And again, geological and geotechnical engineering comes to the rescue there are two very very important areas, geological conservation of the gases and mineralization in situ under the ground. There's another area which is talked about very widely which is a forest station, but as anyone who's lived through the forest fires in California knows, storing carbon in trees is only so good if they burn you simply produce more carbon into the atmosphere. So actually finding ways to a forest and store carbon is a challenge. Logically, we're already on track to do something about this geological sequestration offers many solutions to the way you could store co2 in the ground. Normally we're stalling super critical co2. And there are a number of prototype projects which are in the black dots on the figure on the right. Typically those projects have been running at about a megaton of carbon dioxide a year, sometimes up to about three or four. So to scale this up to the scale where it's significant for the global climate. You can talking about scaling a factor of 1000 1000 of those projects. We could store in depleted oil and gas reservoirs. The beauty about this is those reservoirs are very well characterized. In other words they have cap rocks and so on. But in fact the injection rate needs to be limited so you don't build up pressures that would cause fracturing of cap rocks. That might be an issue of a big concern. There's another advantage for oil and gas you get further enhanced recovery of oil and do this. There's much larger potential it turns out certainly in the US in deep saline aquifers maybe a factor of 10 more potential. One of the challenges the reservoirs are just not that well characterized and trying to understand leakage from them becomes a really big issue. There are other intriguing possibilities. Colbert methane can be extracted by replacing with CO2 for example, that of course doesn't wean us off the fossil fuels but it does achieve some amount of storage of greenhouse gas. One thing that I found fascinating is the emergence of in situ mineralization. If you mix the carbon dioxide with the right reactants in porous basalt which is a basic igneous rock. You can bring about in situ mineralization in the order of months to years. And there have been a number of experiments notably in Iceland that have successfully done this. There have been a lot of experiments that exist all over the world, and there are places where this is going to sound like a really good solution. If I were worrying about coal emissions in India, I would look very closely at the porous basalts. So we have ways forward and geological and geotechnical engineering contributes this big mitigation problem. I'd like to switch to adaptation. It involves many different factors. The one that most people think of initially is mean sea level rise. This figure starts us off in this topic by just showing how mean sea level rise has been recorded historically and what the future projections look like. You will see that we have had rather exquisite data for about 25 years from satellites. And before that we relied on tide gauges and geological inference. The future projections of course depend on the RCP pathways. What you can see in this figure, current rates of sea level rise are up to about 10 millimeters a year as we will see, but you can see there's a very wide range of projected sea level rise by 2100. The two factors here are the deep uncertainties about tipping points in the global climate system. For example, most notably, if West Antarctic ice shelf breaks apart, we could gain up to about 2.4 meters of sea level rise by 2100. These projections show that not happening at RCP 4.5. And you can see that most people are conceiving that sea level rise could be in the range one to one and a half meters by the end of this century, within the time range of planning. You may be less aware of the fact that sea level rise is very regional. The prediction of sea level rise is extraordinarily difficult because of all the different sources of water coming into the oceans. The fact that it's very contingent on the temperature of the water that you're mixing with. So we've got to know more about the temperatures in the deep oceans. What this figure shows is the regional variation, and it shows you roughly the scale of activity. It shows us that sea level trends at the moment are generally bounded between plus and minus 10 millimeters a year, plus being the sea level rise and minus the lowering of the sea level. This is the sort of state of play as interpreted over a 25 year period from satellites. As geological and geotechnical engineers, we kind of know there's something else everyone's missing, which is the issue of erosion and subsidence. If you live in southern Louisiana, you're very conscious of erosion coastal erosion shown in this picture in red, over a 70 year period in the second part of the 20th century. This is eroded a huge part of coastal Louisiana. And the question is, why is erosion so high in these areas. Some of it is simply due to the subsidence. And this is a map of subsidence over a three year period for the greater New Orleans area. The scale is a little annoying, but you'll be able to read it, I think, and you can see that there are parts of this area which are subsiding in the order of 10 to 20 millimeters a year, something like that. In other words, rather comparable to the rates of global sea level rise by the end of this century. So, we don't know the causes of this in New Orleans, but we know it must be a large factor affecting the coastal erosion. Of course, this is nothing compared to some parts of the world. Anthropic subsidence is a huge issue. You can see anthropic subsidence for a series of cities in Asia going all the way back to 1900. And of course this reflects water resources that civil engineers know about, and the use or excessive use of groundwater pumping underneath these cities. You can see how Tokyo stopped or solved its problem around 1970 after 70 years of groundwater pumping, producing four and a half meters of subsidence. And then you look forward and you can see that Jakarta is the champion today. Jakarta is subsiding, according to this INSAR data somewhere between 10 and 20 centimeters a year in order of magnitude larger than sea level rise. So there are parts of the world where industrialization or urbanization and groundwater pumping are far more important than sea level rise from climate change per se. So these are issues that somebody can do something about, and the geological and geotechnical engineers are heavily engaged. When people think about adaptation, however, they think mainly hazards. This is my favorite map in all the years I've worked, I think it brings together two of the biggest hazards we can think of earthquakes, which the community knows a lot about. And tropical cyclones which are cyclonic storms originating in the equatorial regions, and you can see the parts of these in green. At first sight, you can appreciate how this is very important in the US for the Gulf Coast and the East Coast, where a large population is exposed to these storms. This doesn't tell of course the full story of climate change. I'm sure folks in Iowa are not relieved to know that there are storms affecting the East Coast. They've just had one of the largest wind storms in history, the direct show, which did more than $7 billion worth of damage. So it really is only a partial picture. Those of us in Boston also suffer from Nor'easters, which are extra tropical storms, so they don't fit into this picture. But I think you get the idea that these big tropical storms are a very large part of the hazard we face with climate change. In fact, if you look at the damage costs for natural hazards, the light blue ones there are ones which are essentially from these big storms, these big coastal storms. And they're the single most expensive hazard out there, other than the occasional very large earthquake. The damage here is caused primarily by flooding and flooding relates to two separate things. Flooding relates to the storm surge principally caused by the persistence and extent of the wind field that we have with these storms, extreme precipitation, which reflects very much the amount of moisture in the storm and the rate of advance of the storm, the movement of the eye of the storm. Perhaps the most convincing piece of data linking storms and climate change is this piece from my MIT colleague, Kerry Emanuel. What it shows in blue is the sea surface temperature in the mid-Atlantic where these storms develop, these tropical storms develop. And in red it shows you the maximum storm intensity. And hopefully you can appreciate the very close correlation of these two pieces of data over at least the last 50 years. That correlation is a great deal higher than R squared equals 0.58. It's something of the order of 0.8. So we know that storm intensity is growing with sea surface temperature which is related to climate change. We respect with climate change much more intense storms and there's also increasing evidence of increasing frequency in addition to sea level rise. So how does this affect us? Well, in terms of storm surge, we've grown a little complacent because our colleagues in hydrodynamics are rather good at predicting storm surge. What we're seeing in this figure is an advanced prediction of the storm surge probabilities for hurricane Sandy about a day before the storm made landfall. And you can see there's a 50% probability of a surge greater than two meters. In fact, a day later the storm surge was 4.3 meters and drowned lower Manhattan. So the intensification is something we still haven't got to grips with some of the recent storms have generated much more intense storm activity in a very short space of time and that remains a big challenge. Sometimes storms linger and generate enormous amounts of precipitation as Hurricane Harvey did in Houston. Here the challenges were simply overloading aging stormwater infrastructure which needs to be upgraded in some way. It also peculiarly suffers from a lack of zoning and its urbanization. And of course the urbanization itself has limited the infiltration capacity. So Houston is particularly vulnerable to stormwater problems like this. If you look forward and you say well what are we going to do for coastal adaptation and how geotechnical engineers going to fit into this. The most important thing to understand is, we need solutions that address both of these things. The most challenging thing for storm adaptation is that our current regulations actually decoupled these two elements. In other words, the core of engineers deals with storm surge local cities deal with stormwater management. This is a huge challenge for coastal adaptation until we address this. A lot of other things won't work. I mean usually when we think about coastal adaptation, we think about a myriad of different defenses that can put us between the ocean and protect our houses and property. If you look at these from the right to the left you'll realize, we already spend lots of money every year on beach restoration, primarily for recreational purposes but we get storm protection benefits. If you look towards the coast, you see that there are many nature based features these could involve mangrove forest this could involve wetlands tidal marshes and so on, all of which can attenuate some of the storm action. Geotechnical engineers tend to be in the gray infrastructure world of leddies and flood walls. Basically the protection that we provide for the coast is a function of combining these grain green infrastructures, and this is again a challenge for us to come up with integrated ways to do business. Whereas we have some understanding of the performance of walls and levies, quantifying the effectiveness of the nature based features the green infrastructure is still a challenge, although they're often very cost effective. Another strategy for coastal adaptation says we elevate structures, or we improve storm water those are accommodations if you like that says that we can flood without being damaged or experiencing unacceptable damage. There are other strategies to you can think about advance. Many cities in the world have grown through land reclamation. I love to tell my MIT colleagues that our campus is built on reclaimed land just a little over 100 years ago. So land reclamation, which is very much a technical topic, can play a big role here also. Finally, there are going to be communities that are going to have to retreat and retreat is going to present very large socio economical stresses. What about urban storm water management the other side of this story. This is a figure sort of showing the overall hydrology of cities versus green landscapes, and the message should be queered which is you have large rainfall from big storm events extreme precipitation events in a natural environment, a certain fraction of that water infiltrates into the subsurface and a much smaller fraction runs off maybe 10%. In an urbanized setting of operation may look rather similar but because of urbanization there's very little infiltration, and there's much larger run off. So our storm water infrastructure has always been a very big challenge for us with or without climate change. We think in big cities in the east coast of combined sewer outfalls which dump a lot of contaminated water in big storm events. The grand daddy of all gray infrastructure for storm water is in Tokyo, where they've built a flood tunnel, a simply massive underground storage facility to store flood waters for storm infiltration. This is an extremely expensive proposition that reflects the fact that Tokyo such a large population. Many cities are looking at how to improve the soaking up of rain through green infrastructure. So green infrastructures offer a much more attractive proposition if we can increase infiltration very significantly. And these can range from green roofs to bioswales to porous pavements. There's a whole slew of different activities that go into the green infrastructures. And I would suggest in storm water management there's been a shift away from capital intensive gray infrastructures, although I must say in some cases there's new renewal is needed. But there's a shift towards these green infrastructures. And obviously the challenge is to try and show how well they work. And if Trish Culligan were here giving this talk she would tell you a lot about the experience they've had quantifying infiltration in New York City. So let's turn to the damage itself. We already have experienced huge damage from tropical storms hurricane Sandy knocked out the transportation networks and all the tunnels of lower Manhattan. It costs more than $70 billion in damage, about 25 to 30% associated with the infrastructure. Tunnel repairs are still in progress salt water and transit tunnels don't mix very well. So what are our options in New York and how does climate change affect things. Well, if you project forward and you say what's going to happen to New York by 2100. You can anticipate the order of a meter plus or minus half a meter of sea level rise depending on the RCP. The storm surge intensity suggests we could have surges, which are also perhaps a meter plus or minus point two meters higher than present. You can add those two effects, and you will realize that of course, the return period of 100 years that we might design for will become a return period of one in 20 years by 2100. So this is a real challenge for us trying to figure out what is the appropriate way to design this type of infrastructure. The core of engineers is already out designing systems for New York and proposing options I picked just one of a small spore of suggestions they had. This was one of their solutions three a which involves four barriers, protecting the areas you can see in the map. The figure shows the projected storm surge barrier for veritzano narrows. You can see this has got an estimated 20 year construction timeframe, and initial cost estimate of about $34 billion. So we're talking from sets fairly serious money here so we're going to talk a lot of money. We're going to have to decide what the environmental consequences of this do we need this is the is this the appropriate strategy for a city like New York. How do we handle the uncertainties for the climate change predictions, and how do we reduce risk and maintain flexibility and design. This is a huge challenge for us right now. And it's not just affecting New York it's affecting cities up and down the East Coast and the Gulf Coast of the US in particular. It's going to be nice to sort of take a breath and revel in something which is successful at last. Venice has dealt with flooding and resilience for more than 50 years, and it's been flooded on a regular basis by aqua alter events. 1966 was the high water point. It's referred to as the aqua grande 1.96 meters of storm surge did huge damage to the city. Now, November 12 2019, a storm of almost comparable magnitude, more than 50 years later, did about $1 billion worth of damage to the city. Venice of course sits as an island within a lagoon. The lagoon is a man made environment, protecting and preserving this environment making sure that it remains a shallow lagoon is critical to the environmental health of Venice. There are three main wetlands and mud flats and salt marshes and so on. So devising a solution that works both for the city and for the lagoon is rather critical. There are three main openings to the lagoon through which seawater passes flushing lagoon on a daily basis twice daily basis. If you look at what happened to Venice 1973 was declared a priority of national interest, something needed to be done for flood coastal adaptation. You can find mobile barriers for these gates by 94. The environmental impacts the integration of all these schemes for Venice was agreed by about 1998, but it's taken more than 20 years to construct thanks to financing issues. Why do I bring this to your attention. Well, I think it's a triumph, and it's a triumph of engineering in particular geotechnical engineering. One of the barriers came up with a completely unique design, you can see it's a buoyant flapping floodgate it's a hollow steel box, which sits on the seabed and is raised by injecting air so it's a buoyant system. You can see that each of the barriers involves multiple gates and each of the gates flaps independently the gates are any cases up to more than 60 foot high. They operate under conditions with projected sea level rise to handle perhaps another meter of sea level rise or that order. They lie on the seabed they're completely non intrusive they don't affect the function of the lagoon by and large and the rise time is about 30 minutes. The geotechnical engineering is the most critical element because you've got to control the displacements between these two adjacent gates. I can see the hinges the most important element, but the foundation is extremely important. And I reported to you because the first time this gate was being used in a storm was in October this year. It's now being used and kept Venice dry through for storms. Extreme Randfall doesn't just happen on coastal cities. It happens of course very prominently in mountainous terrains. The world record home holder at the moment I think is typhoon morocco hitting Taiwan and dumping almost three meters of rain, causing endless landslides. And one of the things I was curious about was what do we project will happen to landslide risks with climate change. There've been a couple of studies I picked this one from Gariano. And the really only thing to notice here is that by and large we expect landslide hazards to increase over time. And despite all the concern the bottom line is more extreme precipitation events, more landslides. So I don't think there's a profound study here, but it probably tells us that is geological and geotechnical engineers. We're going to be in business for a long time dealing with extreme precipitation events. So in terms of precipitation, we have to think not just of extreme events we have to think about the distribution and how it's spread across the globe annually. How is mean precipitation going to change. This figure shows the projections under 1.5 and two degree warming would stabilization conditions, and you'll see in the in the red colors you will see drought or reductions in amount of rainfall and in blue increases in rainfall. So this is a very regional pattern of rainfall shift. And the question is, how is this going to affect us. As a geotechnical engineer, I think it's important to appreciate that we deal with many things at the ground surface, earth structures, and the interaction of earth structures and the atmosphere is going to become increasingly important as we deal with longer periods of drought cycles and the and in fact, this figure which I borrowed from Phil Varden is a very nice figure illustrating some of the things for a sort of notional structure. I would also point you to two wonderful ranking lectures on this topic one by Jeff Blight 97 and one by Antonio Gens in 2010. They deal with all the technologies all of the partially saturated soils all of the multi phase behavior all of the complexities that go into this problem. But I would suggest to you from a climate change perspective is what we're really asking is, how will these earth structures perform extreme droughts what are the desiccation effects. Can we minimize those effects. Can we improve erosion resistance and durability through stabilization of fields, and there's lots of work going on in stabilization at the moment. Further, what do we do and what do we know about the interactions with vegetation. How can we make vegetations work with our earth structures in constructive ways. So there's lots of scope for us at this scale, but at a larger scale, changes in precipitation must affect water supply and groundwater is our domain to groundwater depletion is a huge problem and a huge challenge predating much climate change. This shows the depletion rates of reservoirs across the US. And in fact if you took the world picture about a one third of worlds aquifers are under stress. In the US we get 38% of our drinking water from groundwater, and we get more than 40% of our irrigation water from groundwater. So these stresses matter to us hugely in terms of long term predictions. And you'll see the some of these in some of the future figures that I'm about to show. I've also been fascinated by how we can combine data to understand groundwater resources. You've seen already subsidence information from INSAR this is the interferometric synthetic aperture radar data this is enabling us to map changes in ground satellite over time. These are data from the Sentinel satellite in the period 2015 to 2017 looking at the central value of sound working Valley in California. And you can see how the drought cycle in this period is brought about a reduction and ground level due to the drawdown in the aquifer. But of course this is just a surface realization. A really interesting piece coming out of remote sensing data now is the ability to start looking below the ground. And there's a recent study on the same aquifer by OJAP, which uses the grace satellite which looks at gravity measurements and looks at gravimetric changes in the subsurface and tries to correlate that with the subsidence. And I think more and more data are going to come from these things which will help us understand and measure how how aquifers are behaving. In this case they compared with ground truth data from wells at various sites. So that's sort of where the story is today. So what is the future predictor prediction from climate changes on groundwater. Well the same picture that you see at the top looks very much what I showed you for soil atmosphere interactions. You can see that we're interested in how changes in rainfall snow melt relate to infiltration and recharge relate to surface radiation and transpiration changes. And we have to put this in the projection of what happens in a future climate. So the question is, how does groundwater storage change if the climate changes according to those different RCP pathways. This is a study which is just starting to get into shape because it requires multi scales of modeling of these things at the global scale. But the paper by Wu is very interesting. It shows how climate change links to the performance of certain key aquifers. You'll see in this figure seven aquifers, the distributed all around the world, and you'll see in the bottom plots, the expected time change of aquifer storage for the RCP 8.5 scenario And it's kind of interesting because when you combine all this information you realize that the rainfall isn't really all the driver here. It's very much related to a Vapo transpiration. And the picture varies depending which part of the world you're in. There are winners and losers in aquifers. You will see the central valley is relatively stable. The southern plains, the southern part of the Ogallala aquifer goes down. There are huge problems in the Middle East, but there are winners you see Northwestern India. This is the Ganges aquifer is actually likely to be recharged at a higher rate. So in groundwater resources and availability of water, these shifts are going to have very big changes in where water resource has to come from. And geotechnical engineers are certainly going to be involved in figuring out how to supply that water. Andrew, we need to kind of wrap up three more slides. I just wanted to say something about climate change in the Arctic. When you look at the Arctic regions, you're aware that they're underlying primarily by permafrost permanently frozen ground. Of course, the Arctic is warming it twice the global mean. It's relatively sparsely populated. You know a lot about sea ice reductions. And you realize this is an area where there's going to be increased economic activity in future. Hazards due to thawing permafrost, subsidence, landsliding, huge damage to infrastructures. And I'm reminded of the fact that we've known about these problems since the construction of the Alaska pipeline. So we're aware of trying to stabilize infrastructure on these situations. A nice study which has just appeared looks at how all of the infrastructures are affected in climate change by the middle of the century. And you'll realize almost every infrastructure component in the Arctic region is going to be affected by the thawing effects. I'm going to require reconstruction. So this is a huge challenge for us. And to round this thing all the way back to where I started. Of course, permafrost is a huge store of greenhouse gases of carbon in the ground. And as anthropogenic warming occurs and we thaw permafrost, we have a potential carbon feedback into the atmosphere. And so I would throw out the last challenge and perhaps the biggest one to you as a community. How do we stabilize this process. How do we prevent a lot of negative feedback coming from melting permafrost. I think that's a real challenge. Fortunately, it's not immediately on our plate, but it will be by the end of this century. And with that, and Alan's reminder, I'd just like to thank you all very much for your attention and leave you to unleash your natural curiosity about all these things. Thank you very much. Well, Andrew, that was just great. Rather, you know, big broad view but a lot of specifics in there for us as geotechnical engineers. And you, you got a last chance here to submit a question if you'd like, we're trying to skew skew those up. And Professor Pedro is going to help us with those. Let's see here just make sure I think that's all I need to do right now except just again it was great lecture, Andrew, we really appreciate it. So Pedro, you want to take over now and give us some challenging questions. Thank you very much for the presentation. It was, it was really, really good. So we have been collecting some questions here. So I will ask you some of them and let's see how far we can go. Some of them are easy. Let's start with these ones. Yeah, so you were talking about some of your slides about rejected energy. What is rejected energy? You have that in the chart of energy use. Rejected rejected energy when we use air conditioners in the summer we cool down the inside of our buildings, we're rejecting heat. So we're heating up the outside environment. So that is rejected heat into the environment. In fact, that causes another feedback into urban situations where you get urban heat island effects. So being able to take that rejected heat and put it into the ground putting it somewhere where it doesn't actually cause distress for people walking around city streets. Rejected heat, for example. So here that is what I will try to combine two here. And what it says that extreme events pattern in a climate change is no. We approach or adapt our geotechnical designs for this hundred year storm events. And what I want to add to that is the timing because you were showing the hazard of storm and an earthquake, but they don't happen at the same time. And how do we adapt to this. And adding to add what is the role of modern geotechnical monitoring in the flame in the face of all these things. Monitoring of course is key to all these things monitoring is about understanding climate change as well as well as understanding the performance of our structure so monitoring is key to all of this. So I didn't sort of try and frame it that way but the question you ask is the tricky one which is, you know, how do you how do you design things with big uncertainties about your design parameters, because you have to pick. You know, in designs you have to start with some notion for example of extreme sea levels that you're going to design to. So it does set the parameters for design. I'm not sure what you've got many, many parts that question you said modern geotechnical engineering. I mean geotechnical engineering is is adapting all the time so designing things with better erosion resistance using materials more effectively there's there's many versions of that so I'm not quite sure how else you. It's a little try try again, try again see if you can. Right direction. Yeah, so. The thing is, for me in the question what they are what this person is trying to ask is, and how do you adapt. So we have codes, we have design approaches, should we be changing all these codes that we have already in place or not. And. Well, you. If we're designing new things with old codes aren't going to work necessarily so so they are going to require adaptation. I would like to think that codes are also adapting as they move forward but I'm not closely involved in code development. Like, do you see progress in the UC progress in this. I see the problem I see is not I mean I don't necessarily see it from a geotechnical perspective but I see we're reactive very often. For example, in recent coastal storms has been a recognition that a lot of power infrastructure in the basements of buildings makes them very vulnerable. And yet the design regulations on buildings require them to be put in basements. So power plants for hospitals are particularly vulnerable. So after Hurricane Sandy a lot of regulations change. So regulations change. Do design codes change. I would hope design codes preserve safety of course. But then they change over over a longer timeline perhaps. So the question with climate change is how quickly are we having to respond to these things and what is a reasonable projection. Most infrastructure is designed with a 50 year notional 50 year window, but there's an awful lot of infrastructure we're using which is 100 150 years old so it is a challenge for us I have to confess. But here that was a question is I think it's also kind of a specific. And do you see the repurposing of oil and gas wells for geotechnical development geothermal developments. Could they be used for you because they you know they are in the ground they are. Yes they are but they're not terribly helpful because they're not necessarily in the rocks with the right kind of temperature. But you're most interested in for geothermal. You're most interested where the temperature is high enough for the shortest drilling distance you're probably looking at igneous rocks and fracturing of igneous rocks rather than than sandstones and the like which would be the characteristic. I'm not saying that sedimentary rocks can't possibly go I'm just saying igneous rocks tend to be those with higher temperatures. It is a somewhat different scenario I would say for the hot dry rocks yeah. And, okay. Here, another one. How does it reclaim land impact sea level rise countries like China and Japan plan to generate a new land by feeling reclaim land for urban development. Are there studies on this impact on what to do with reclaim land that you are aware of. Yeah, well I'm aware that people have looked I mean there's a lot of land reclamation around Shanghai and I'm aware that people are doing a lot of geotechnical analysis on the subsidence of the reclaim land and how, how much subsidence is going to occur relative to sea level rise. So there's a concern of that kind. But by and large our capacity to extend our waterfront outwards exceeds the challenge of the slow moving sea level rise. So I've worked a lot in Singapore over the last few years and the whole country has decided to decreed that it will have a coastline which is higher than it currently has. So, you know, you can conceive of doing this of course many countries have put land reclamation as a way of handling their position the Netherlands of course famously puts a lot of barriers between the sea and the cities. And there's plenty of examples of land reclamation operating perfectly successfully but but the geotechnical side of this is finding cost effective ways to do it, making realistic predictions of how, how things perform so. I'll just mention a little differently that maybe they're asking if the volume taken up by land reclamation affects sea level rise. Yeah, I didn't think this and this is not not not. I suppose it's possible scenarios locally but not that I'm aware of the volumes are tiny really. I miss that sorry. So here. And why do you choose the greenhouse emissions pathway figure with the net zero needed to be achieved in 2090 to meet a two degrees thousand gold. Here the question is I think most IPCC projections are much earlier like for the 2060 or earlier. Why do you choose the 29. Oh, the figure I showed there. What I showed was the team two degrees stabilization line. So that was a line if you stabilize at two degrees C by 2090. No I agree there's people trying to achieve stabilization and lower, lower global temperature is sooner. This is a bit of a moving target because the target set by governments are generally been underachieved and there's generally more and more dial warnings being produced. But I just want to point out this is a trajectory we're going on, but decarbonizing doesn't end with, you know, we're not going to deep carbonize the whole economy just like that. So my point was really to recognize the fact that there's going to need to be more storage greenhouse gases and that was really what I was trying to point out. One final question because I think that we are reaching the time and after that we may see what we do but in a lot of what we are talking uncertainties it seems to be an important aspect to consider so the question was, how can we address climate change and certainties in geotechnical analysis and design. I hate to overemphasize the uncertainties in the timeframe of the next 60 to 80 years. Providing we are following the sort of mitigation pathways we're on the RCP 4.5 line for example may well get adopted as a practical design that doesn't answer questions about how climate change may project going forward over hundreds of years. So I don't think we're, it's that uncertain Petra I think we're not, we're not living with. Well with the things that would make it a lot more uncertain are very big drivers like the West Antarctic is certainly an uncertainty. But it's not in our immediate 10 to 20 year horizon, probably not in our horizon for designs that are going on today. It could well be if we don't follow or don't achieve some control over greenhouse gas it could become a big problem for us. So it's sort of a warning out there it's a lurking warning. Okay I think that we have reached the time here so first of all from my perspective thank you very much. There are several other questions here that you may want to look and maybe find a way to respond them maybe extra time or in another format. I will pass now the control to Alan's for your last words. Yes, thank you Professor Arduino. And thank you so much, Professor little that was really extraordinary and fascinating and I think what it showed is there's a huge future for geotechnical engineers that want to dive into these any one of these areas and challenges right on those fringes of very important questions to society. I remind you that we will post this webinar online and that information will be sent out to each one of you. Sometime in the next day or two as to where where you will find that there are over 400 of you that participated as I monitored this still almost 300 of you still here indicating a high level of interest so congratulations Andrew and drawing a great crowd. Also, I have to again remind us a disclaimer that any opinions conclusions or recommendations expressed by anyone during this webinar or those of the individuals and not the representing the National Academies in any way. And thank you all for joining us it would be nice if we were all in one big room and could continue this discussion I'm sure it would be lively and go on for quite a while but unfortunately we can't do that let's look forward to it in the near future. Thank you everybody and all those who helped do this and we look forward to the next webinar.