23 -- Medieval Warm Period -- fact vs. fiction

This video looks at the scientific research to answer three basic questions: 1) Was the Medieval Warm Period global? 2) Was it warmer than today? 3) And what does this all mean anyway? I examine the internet feud over the hockey stick and the various myths and misinterpretations about the Medieval Warm Period that seem to be rife on the Internet. My sources for the myths are blogs and videos; my sources for the facts are scientific papers.

CORRECTION AT 5:51: The graph without recent temperatures is not the work of a blogger after all, it comes from the researchers themselves. This does not change the fact that this graph was used by the Daily Mail to incorrectly infer that the MWP was warmer than today, while the graph the researchers used to show recent temperatures was not shown.

SOURCES

0:45 Christopher Monckton interview with Michael Coren

01:23 http://www.co2science.org/education/r...
and
http://scienceandpublicpolicy.org/ima...


02:18 Ibid

02:42 "Global-scale temperature patterns and climate forcing over the past six centuries" -- ----- Mann Bradley and Hughes, Nature 1998

02:50 "Northern Hemisphere Temperatures During the Past
Millennium: Inferences, Uncertainties, and Limitations" Mann Bradley and Hughes, American Geophysical Union. 1999

03:03 "Hockey sticks, principal components, and spurious significance" -- McIntyre and McKitrick, Geophysical Research Letters 2005

03:18 "Surface Temperature Reconstructions for the Last 2,000 years" National Academy of Sciences

03:41 "Ad Hoc Committee Report on the 'Hockey Stick' Global [sic] Climate Reconstruction" -- Edward Wegman, published in Computational Statistics and Data Analysis 2008

"Climate study gets pulled after charges of plagiarism" http://www.usatoday.com/weather/clima...

04:21 "Proxy-based reconstructions of hemispheric and global surface temperature variations
over the past two millennia" Mann et al, PNAS 2008

05:10 "Orbital Forcing of Tree Ring Data" Esper et al, Nature Climate Change 2012

05:20 Daily Mail story: http://www.dailymail.co.uk/sciencetec...

06:23 "A NEW RECONSTRUCTION OF TEMPERATURE VARIABILITY IN THE EXTRA-TROPICAL NORTHERN HEMISPHERE DURING THE LAST TWO MILLENNIA" Lungqvist, Swedish Society for Anthropology and Geography 2010

07:00 "Catastrophe Denied" by Warren Myer

07:37 "Highly variable Northern Hemisphere temperatures reconstructed from
low- and high-resolution proxy data" -- Moberg, Nature 2005

08:21 "A 2000-YEAR GLOBAL TEMPERATURE RECONSTRUCTION
BASED ON NON-TREERING PROXIES" -- Loehle 2007

08:28 Joannenova.com

08:40 "Correction to: A 2000-YEAR GLOBAL TEMPERATURE
RECONSTRUCTION BASED ON NON-TREE RING PROXIES" Loehle 2008

08:50 Ibid

09:01 http://www.skepticalscience.com/new-r...

09:15 "The Great Global Warming Swindle" -- by Martin Durkin Channel 4

09:26 "Global Warming Sunspots Explained" by David Archibald

09:31 "Catastrophe Denied" by Warren Myer

09:35 "The Truth About Global Warming" by David Icke

09:48 IPCC report, Chapter 7, 1990
10:10 McIntyre

10:19 "High-resolution palaeoclimatology of the last millennium: a review of current
status and future prospects" Jones et al, The Holocene, 2009

11:40 Global Warming (or is it Global Cooling)' http://rogerfromnewzealand.wordpress....

14:59 Joannenova.com

17:24 "Unstoppable Solar Cycles"
http://www.youtube.com/watch?v=Cl4Pz1...


19:10 "Extra-tropical Northern Hemisphere land temperature variability over the past 1000 years" Cook et al., Quaternary Science Reviews 2004

19:24 "Long-Term Aridity Changes in the Western United States" -- Cook et al, Science 2004
See also: "Drought Reconstructions for the Continental United States" -- Cook et al, Journal of Climate 2004

19:27 "The 'Mediaeval Warm Period' drought recorded in Lake Huguangyan, tropical
South China" -- Chu et al, The Holocene 2002

19:29 "Amazonia suffered immense drought between 700-800 AD and 1000-1100 AD" (Fire, Climate Change and Biodiversity in Amazonia: a Late Holocene Perspective. M. Bush. Phil. Trans. Royal Society. 2008. Archaeological Evidence for the Impact of Mega-Nino Events on Amazonia during the past two Millennia. B. Meggers. Smithsonian. 1994.)

19:33 http://www.newscientist.com/movie/usmap

19:45 "Drought Under Global Warming: a review" -- Aiguo Dai, Wiley Interdisciplinary Reviews: Climate Change 2011
https://www2.ucar.edu/atmosnews/news/...

• Category

  Science & Technology

[vagrant2502]

I might point out that we may have not had cars, but we certainly burnt alot of things back then. 

[potholer54]

=but we certainly burnt alot of things back then= I am not sure what you are suggesting. Could you elaborate?

[vagrant2502]

Sorry, I was refering to the "Dont Have SUVs in the Middle Ages" bit in regards to the actual saying. We had been using fire for some time, and we liked burning things (smelters, people, limestone, coal etc). While it may not be on the car scale we still were throwing alot of CO2 and other not nice fumes in the air for what, four or five thousand years?

[potholer54]

That's what I thought. But this has nothing to do with climate change, and was certainly not a cause of the MWP. It has never even been suggested, because the amount of CO2 emanating from hearths and smelters was minimal prior to the industrial revolution. CO2 levels have been stable for thousands of years.

[davidandhisguitar]

This video makes me believe you are intentionally misleading people with half truths and misdirection. I came to this realization at about 6:32 in the video when you only read half of the underlined statement. This is a crux of the issue. The instrument data being tacked on to the proxy data and the the veracity of that instrument data. If you don't know what I'm talking about, then you don't understand what the questions are to being with and are only propagandizing.

[potholer54]

= I came to this realization at about 6:32 in the video when you only read half of the underlined statement. = Thanks. I underlined this statement myself, so I am puzzled as to why you think it was misleading to paraphrase it. I don't feel I have to read everything to viewers, if I underline something I assume they are perfectly capable of reading it for themselves. If there is any misleading or incorrect information in the video, please point it out and I will be happy to correct it.

[raverdeath100]

not really. i doubt if your boat bobbing up and down constitutes that much in the current climatic models. you should to the UK. our weather is changing quite dramatically, i can assure you. we have towns that have lived with rivers, quite happily, for over a 1000 years. not anymore. we spend 10 times the amount on flood defences, than we did about 20 years ago. so does the US roughly.

[mikedelhoo]

Global average sea level rise is less than an inch per decade - I'm guessing it'd be hard to notice that unless you were deliberately measuring it. (That's global mind you, no idea about Miami. Ref. Wikipedia "Current sea level rise".)

[taiwanjohn88]

Peter: Have you seen this talk by Allan Savory? watch?v=vpTHi7O66pI

I'd be very curious to know to what extent climate scientists have studied the relationship between desertification in early "civilised" history and temperature changes. I've heard some conjecture that the "Columbian exchange" may have brought cooling, as indigenous peoples were wiped out, allowing forest to regrow. But might the same be said of the fall of the Roman empire?

[naturfagstoff]

So did the Medival and Roman warm periods exist, or is that still fiction, according to You?

[naturfagstoff]

Compare the graphs you used to recent satellitte data and oceanic temperature, and see what you come up with..

[evelsteev]

So this is supposed to undeniably prove that humans are causing global warming? Why wasn't it warmer during the industrial revolution and post-World War II era?

[Yvonne Thompson]

dung was used for fire all the time, so was straw, dead leaves, the standard wood, every home had a fire place, every holiday seemed to have a bonfire,

[debrainwasher1]

Co2 traps heat because it is dense, much like the mind of climate deniers.

[DLSacks]

Not sure which of your videos to post this very sincere question, but what resources to you suggest for access to academic journals and research? I had incredible access when I was a college student a decade ago, but I'm likely to never have that kind of access again. Individual articles or journal subscriptions come with a hefty price tag.

[forestsoceansmusic]

Congress (or any government commissioned studies) have a vested interested in raising a new tax on an essential element so that everyone has to pay it - probably to pay for their wars of aggression in Central Asia.

[Gareth Tudor]

A bit off-topic, I know, but I was wondering if Lord M is related to Marty Feldman...