SINGAPORE The pace of global warming continues unabated, scientists said on Thursday, despite images of Europe crippled by a deep freeze and parts of the United States blasted by blizzards.
The bitter cold, with more intense winter weather forecast for March in parts of the United States, have led some to question if global warming has stalled.
Understanding the overall trend is crucial for estimating consumption of energy supplies, such as demand for winter heating oil in the U.S. northeast, and impacts on agricultural production.
"It's not warming the same everywhere but it is really quite challenging to find places that haven't warmed in the past 50 years," veteran Australian climate scientist Neville Nicholls told an online climate science media briefing.
"January, according to satellite (data), was the hottest January we've ever seen," said Nicholls of Monash University's School of Geography and Environmental Science in Melbourne.
"Last November was the hottest November we've ever seen, November-January as a whole is the hottest November-January the world has seen," he said of the satellite data record since 1979.
The World Meteorological Organization (WMO) said in December that 2000-2009 was the hottest decade since records began in 1850, and that 2009 would likely be the fifth warmest year on record. WMO data show that eight out of the 10 hottest years on record have all been since 2000.
Britain's official forecaster, the UK Met Office, said severe winter freezes like the one this year, one of the coldest winters in the country for nearly 30 years, could become increasingly rare because of the overall warming trend.
Scientists say global warming is not uniform in all areas and that climate models predict there will likely be greater extremes of cold and heat, floods and droughts.
"Global warming is a trend superimposed upon natural variability, variability that still exists despite global warming," said Kevin Walsh, associate professor of meteorology at the University of Melbourne.
"It would be much more surprising if the global average temperature just kept on going up, year after year, without some years of slightly cooler temperatures," he said in a written reply to questions for the briefing.
The scientists also defended the U.N. climate panel after it came under attack for including an error about the estimated thaw of Himalayan glaciers in a major 2007 report.
The Intergovernmental Panel on Climate Change (IPCC) produces reports based on the work of thousands of scientists that are the main guides for policymakers on tackling global warming. The discovery of the error has been seized upon by climate skeptics.
The 2007 report wrongly said Himalayan glaciers could all melt by 2035, an apparent typographical error that stemmed from using "grey literature" outside peer-reviewed scientific journals.
Nicholls said grey literature could play a key role in the climate debate and that not all valuable data or reports were published formally in journals. Such examples included reports on extreme weather events by government meteorological agencies.
"The IPCC does not exclude the use of that sort of grey literature because it would be stupid to talk about extremes, for instance, and not include that sort of grey literature," he said.
The scientists said more stringent checks were needed for the next IPCC reports but that the inclusion of one or two wrong predictions didn't undermine the whole peer-reviewed IPCC process because scientific study was always evolving.
(Editing by Paul Tait)