FEBRUARY 10, 2011
The Weather Isn’t Getting Weirder
The latest research belies the idea that storms are getting more extreme.
By ANNE JOLIS
Last week a severe storm froze Dallas under a sheet of ice, just in time to disrupt the plans of the tens of thousands of (American) football fans descending on the city for the Super Bowl. On the other side of the globe, Cyclone Yasi slammed northeastern Australia, destroying homes and crops and displacing hundreds of thousands of people.
Some climate alarmists would have us believe that these storms are yet another baleful consequence of man-made CO2 emissions. In addition to the latest weather events, they also point to recent cyclones in Burma, last winter’s fatal chills in Nepal and Bangladesh, December’s blizzards in Britain, and every other drought, typhoon and unseasonable heat wave around the world.
But is it true? To answer that question, you need to understand whether recent weather trends are extreme by historical standards. The Twentieth Century Reanalysis Project is the latest attempt to find out, using super-computers to generate a dataset of global atmospheric circulation from 1871 to the present.
As it happens, the project’s initial findings, published last month, show no evidence of an intensifying weather trend. “In the climate models, the extremes get more extreme as we move into a doubled CO2 world in 100 years,” atmospheric scientist Gilbert Compo, one of the researchers on the project, tells me from his office at the University of Colorado, Boulder. “So we were surprised that none of the three major indices of climate variability that we used show a trend of increased circulation going back to 1871.”
In other words, researchers have yet to find evidence of more-extreme weather patterns over the period, contrary to what the models predict. “There’s no data-driven answer yet to the question of how human activity has affected extreme weather,” adds Roger Pielke Jr., another University of Colorado climate researcher.
The Twentieth Century Reanalysis (20CR) project is an international effort to produce a comprehensive global atmospheric circulation dataset spanning the twentieth century, assimilating only surface pressure reports and using observed monthly sea-surface temperature and sea-ice distributions as boundary conditions. It is chiefly motivated by a need to provide an observational dataset with quantified uncertainties for validations of climate model simulations of the twentieth century on all time-scales, with emphasis on the statistics of daily weather.
It is anticipated that the 20CR dataset will be a valuable resource to the climate research community for both model validations and diagnostic studies. Some surprising results are already evident. For instance, the long-term trends of indices representing the North Atlantic Oscillation, the tropical Pacific Walker Circulation, and the Pacific–North American pattern are weak or non-existent over the full period of record. The long-term trends of zonally averaged precipitation minus evaporation also differ in character from those in climate model simulations of the twentieth century. Copyright © 2011 Royal Meteorological Society and Crown Copyright.
“So we were surprised that none of the three major indices of climate variability that we used show a trend of increased circulation going back to 1871.”
“The three major indices of climate variability” show no evidence that climate change is having any affect on extreme weather events…
Which makes sense… Because there is no evidence that climate extremes are increasing either…