There is an article in the March-April 2010 publication The Earth Observer titled
Cold Snaps Plus Global Warming Do Add Up” by Patrick Lynch, NASA Langley Research Center.
The article has an informative discussion of the role of atmospheric circulations in weather and climate (as well as several excellent images of snow cover this winter), but also a rather remarkable statement on global warming as related to the recent cool weather.
The article starts with the text
“That feeling of numbness in your toes, even inside your thickest boots, is not lying to you. It’s been very cold so far this winter in most of the U.S. and many places at middle latitudes in the Northern Hemisphere. Washington, DC, London, U.K., and Seoul, South Korea have already shoveled themselves out from major snowfalls. And over the course of 2009, average temperatures across some parts of the U.S. were cooler than the average temperature for a baseline period of 1951–1980.
To many people’s confusion, these weather events happened against a backdrop of increasing man-made greenhouse gas levels in the atmosphere that are gradually warming the planet. But scientists stress this weather does not mean that those gases are no longer exerting a warming influence. Nor does it go against the grain of basic global warming theory. Cold snaps and bouts of natural cooling that could last years are expected naturally even as the climate continues on a long-term warming trend, forced by man-made emissions.”
The statement that “bouts of natural cooling that could last years are expected naturally even as the climate continues on a long-term warming trend, forced by man-made emissions” conflicts with the IPCC finding of more-or-less monotonic warming (interspersed with only periods of a few years with slight cooling or no warming). How can you have warming and cooling at the same time! A cooling and a warming trend do not “add up”.
The added CO2 is a radiative warming effect, but the failure of the IPCC modeling assessment to anticipate that societally important cold periods will still occur is a serious oversight.
The article also writes
The bottom line is, I don’t find it extraordinary,” Wallace said. “With or without anthropogenic (man-made) warming, you’re going to have big variations in these patterns.” [John Wallace isa well-respected atmospheric sciences professor at the University of Washington].
I agree with John Wallace which is why we need to focus on regional climate variations and change, not on the current climate “gold standard” which is the global average surface temperature trend. We also need to recognize that climate (and the human role in the climate system) is more complex than reported in the 2007 IPCC report.