A Duke University-led study questions the reliability of the climate models used to project short-term swings in temperature and the future extent of warming.
Patrick Brown, a Duke doctoral student in climatology, and two coauthors analyzed 34 models used by the Intergovernmental Panel on Climate Change in its most recent report, completed in November.
Most of the models probably underestimate how much surface temperatures change from decade to decade, says the study published last week in the Journal of Geophysical Research. The models also don't consistently explain why they vary, it says.
That means too much emphasis shouldn't be placed on recent temperature trends, the study warns.
"The inconsistencies we found among the models are a reality check showing we may not know as much as we thought we did," Brown said in a Duke release. He added that the findings don't mean the planet won't warm as greenhouse gases accumulate in the atmosphere.
"It just means the road to a warmer world may be bumpier and less predictable, with more decade-to-decade wiggles than expected.... Don't assume that the reduced rate of global warming over the last 10 years foreshadows what the climate will be like in 50 or 100 years."
Global surface temperatures rose quickly in the 1980s and 1990, but have stayed relatively stable since then.
The National Climatic Data Center in Asheville reported that surface temperatures in 2014 were the warmest since record-keeping began in 1880. Nine of the 10 warmest years in that 135-year span have occurred in this century.
Martin's coauthors were Wenhong Li of Duke's Nicholas School of the Environment and Shang-Ping Xie of the University of California San Diego.
(First posted on Monday, Jan. 26, 2015. For older posts, go here.)