Yes, the extreme cold in the UK right now really could be a result of global warming.
By George Monbiot. Published in the Guardian 21st December 2010
There were two silent calls, followed by a message left on my answerphone. She had a soft, gentle voice and a mid-Wales accent. “You are a liar Mr Monbiot. You and James Hansen and all your lying colleagues. I’m going to make you pay back the money my son gave to your causes. It’s minus 18 degrees and my pipes have frozen. You liar. Is this your global warming?”. She’s not going to like the answer, and nor are you. It may be yes.
There is now strong evidence to suggest that the unusually cold winters of the past two years in the UK are the result of heating elsewhere. With the help of the severe weather analyst John Mason and the Climate Science Rapid Response Team(1), I’ve been through as much of the scientific literature as I can lay hands on. (Please also see John Mason’s article, which explains the issue in more detail(2)). Here’s what seems to be happening.
The global temperature maps published by NASA present a striking picture(3). Last month’s shows a deep blue splodge over Iceland, Spitsbergen, Scandanavia and the UK, and another over the western US and eastern Pacific. Temperatures in these regions were between 0.5 and 4 degrees colder than the November average from 1951 and 1980. But on either side of these cool blue pools are raging fires of orange, red and maroon: the temperatures in western Greenland, northern Canada and Siberia were between two and ten degrees higher than usual(4). NASA’s Arctic oscillations map for December 3-10 shows that parts of Baffin Island and central Greenland were 15 degrees warmer than the average for 2002 to 2009(5). There was a similar pattern last winter(6). These anomalies appear to be connected.
The weather we get in UK winters, for example, is strongly linked to the contrasting pressure between the Icelandic Low and the Azores High. When there’s a big pressure difference, the winds come in from the south-west, bringing mild, damp weather from the Atlantic. When there’s a smaller gradient, air is often able to flow down from the Arctic. High pressure in the icy north last winter, according to the US National Oceanic and Atmospheric Administration(NOAA), blocked the usual pattern and “allowed cold air from the Arctic to penetrate all the way into Europe, eastern China, and Washington DC”(7). Another US agency, NASA, reports that the same thing is happening this winter(8).
Sea ice in the Arctic has two main effects on the weather. Because it’s white, it bounces back heat from the sun, preventing it from entering the sea. It also creates a barrier between the water and the atmosphere, reducing the amount of heat that escapes from the sea into the air. In the autumns of 2009 and 2010, the coverage of Arctic sea ice was much lower than the long-term average: the second smallest, last month, of any recorded November(9). The open sea, being darker, absorbed more heat from the sun in the warmer, light months. As it remained clear for longer than usual, it also bled more heat into the Arctic atmosphere. This caused higher air pressures, reducing the gradient between the Iceland Low and the Azores High.
So why wasn’t this predicted by climate scientists? Actually it was, and we missed it. Obsessed by possible changes to ocean circulation (the Gulf Stream grinding to a halt), we overlooked the effects on atmospheric circulation. A link between summer sea ice in the Arctic and winter temperatures in the northern hemisphere was first proposed in 1914(10). Close mapping of the relationship dates back to 1990, and has been strengthened by detailed modelling since 2006(11,12,13,14,15,16).
Will this become the pattern? It’s not yet clear. Vladimir Petoukhov of the Potsdam Institute says that the effects of shrinking sea ice “could triple the probability of cold winter extremes in Europe and northern Asia.”(17) James Hansen of NASA counters that 7 of the past 10 European winters were warmer than average(18). There are plenty of other variables: we can’t predict the depth of British winters solely by the extent of sea ice.
I can already hear the howls of execration: now you’re claiming that this cooling is the result of warming! Well yes, it could be. A global warming trend doesn’t mean that every region becomes warmer, every month. That’s what averages are for: they put local events in context. The denial of manmade climate change has mutated first into a denial of science in general, now into a denial of basic arithmetic. If it’s snowing in Britain, a thousand websites and quite a few newspapers tell us, the planet can’t be warming.
According to NASA’s datasets, the world has just experienced the warmest January-November since the global record began, 131 years ago(19). 2010 looks likely to be either the hottest or the equal hottest year. This November was the warmest on record(20).
Sod all that, my correspondents insist: just look out of the window. No explanation of the numbers, no description of the North Atlantic Oscillation or the Arctic Dipole, no reminder of current temperatures in other parts of the world, can compete with the observation than there’s a foot of snow outside. We are simple, earthy creatures, governed by our senses. What we see and taste and feel overrides analysis. The cold has reason in a deathly grip.
7. J. Overland, M. Wang, and J. Walsh, 14th October 2010. Arctic Report Card. http://www.arctic.noaa.gov/reportcard/atmosphere.html
9. National Snow and Ice Data Center (NSIDC) reported on 6 December 2010. ***
10. HH Hildebrandsson, 1914. Cited by Dagmar Budikova, 2009. Role of Arctic sea ice in global atmospheric circulation: A review. Global and Planetary Change Vol 68, pp 149–163. doi:10.1016/j.gloplacha.2009.04.001
11. There’s a review of the science until early 2009 at:
Dagmar Budikova, 2009. Role of Arctic sea ice in global atmospheric circulation: A review. Global and Planetary Change Vol 68, pp 149–163. doi:10.1016/j.gloplacha.2009.04.001
12. More recent modelling work is summarised by James Overland and Muyin Wang, 2010. Large-scale atmospheric circulation changes are associated with the recent loss of Arctic sea ice. Tellus Vol 62A, pp1–9. doi: 10.1111/j.1600-0870.2009.00421.x
See also the following recent papers:
13. Jennifer A. Francis et al, 2009. Winter Northern Hemisphere weather patterns remember summer
Arctic sea-ice extent. Geophysical Research Letters, Vol. 36, L07503, doi:10.1029/2009GL037274.
14. Meiji Honda, Jun Inoue and Shozo Yamane, 2009. Influence of low Arctic sea-ice minima on anomalously cold Eurasian winters. Geophysical Research Letters, Vol. 36, L08707. doi:10.1029/2008GL037079.
15. Vladimir Petoukhov and Vladimir* Semenov, 2010. A link between reduced Barents-Kara sea ice and cold winter extremes over northern continents. Journal of Geophysical Research, Vol 115, D21111. doi:10.1029/2009JD013568.
16. Chunzai Wang, Hailong Liu, Sang-Ki Lee, 2010. The record-breaking cold temperatures during the winter of 2009/2010 in the Northern Hemisphere. Atmospheric Science Letters, Volume 11, Issue 3, pp 161–168. doi: 10.1002/asl.278
18. James Hansen, Reto Ruedy, Makiko Sato and Ken Lo, 13th December 2010. GISS Surface Temperature Analysis: 2010 – Global Temperature and Europe’s Frigid Air. http://data.giss.nasa.gov/gistemp/2010november/
19. James Hansen et al, as above.
20. James Hansen et al, as above.