Climate Models Conflict When it Comes to Explaining Temperature 'Wiggles'

Temperature variability is important to take into account when it comes to long-term trends. Now, though, scientists have discovered that climate models may disagree on why these temperature "wiggles" occur.

"The inconsistencies we found among the models are a reality check showing we may not know as much as we thought we did," said Patrick Brown, one of the researchers, in a news release. "This doesn't mean greenhouse gases aren't causing Earth's atmosphere to warm up in the long run. It just means the road to a warmer world may be bumpier and less predictable, with more decade-to-decade temperature wiggles than expected. If you're worried about climate change in 2100, don't over-interpret short-term trends. 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."

The researchers analyzed 34 climate models used by the Intergovernmental Panel on Climate Change (IPCC) in its fifth and most recent assessment report. While the scientists found good consistency among the models explaining the causes of year-to-year temperature wiggles, they found inconsistencies in the models' abilities to explain decade-to-decade variable. For example, the models had trouble explaining why global mean surface temperatures warmed quickly during the 1980s and 1990s and have remained relatively stable since then.

"When you look at the 34 models used in the IPCC report, many give different answer about what is causing this decade-to-decade variability," said Brown. "Some models point to the Pacific Decadal Oscillation as the cause. Other models point to other causes. It's hard to know which is right and which is wrong."

The findings are published in the Journal of Geophysical Research.

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