|Courtesy Skeptical Science|
One swallow doesn’t make a spring, and nor does one scientific paper change a whole body of evidence. But you could be mistaken for thinking so after the poor media coverage last week of a new piece of climate research.
A study published last week in Nature(“Emergent constraint on equilibrium climate sensitivity from global temperature variability”) claims to tighten the Intergovernmental Panel on Climate Change (IPCC), range for (short-term) Estimated Climate Sensitivity (ECS), the amount of warming to be expected from a doubling of carbon dioxide (CO2) in the atmosphere.
The study puts its best guess at 2.8C, which is pretty squarely in the middle of what scientists have thought all along. It also affirms that the best-case scenario of little-to-no warming, which deniers point to as justification for inaction, is unlikely, as are the worst-case, “black swan” scenarios.
But because the AFP write-up was framed around the worst-case scenarios being “not credible,” deniers are celebrating the study as some sort of win.
Now this study, and particularly AFP’s coverage, isn’t particularly helpful from either a scientific or a communications standpoint. For one thing, it’s based on recent short-term variation, not thousands of years of temperature data, like other paleo-climate based ECS studies. Plus, it uses a brand new modeling methodology–not exactly a tried-and-true approach. But apparently those who rail against climate models as hopelessly inaccurate will eagerly believe model outputs if they think it supports their denial.
Then there’s the whole “single-study-syndrome” issue, so we should take the findings with a grain of salt, especially given other recent studies putting ECS at the higher end of what’s likely. This new modeling exercise doesn’t take tipping points into account, meaning that – oops – those worst-case scenarios are still very much on the table if steady warming triggers rapid changes in glacier melt or ocean circulations or any other unexpected surprises.
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