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New Study Suggests Climate Change May Be (Slightly) Less Severe Than Feared

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Research on the Ice Age is giving us a better picture of climate change.

Earlier this week unknown hackers—following up from a similar attack two years ago—released a cache of stolen emails from climate scientists. Climate skeptics—just as they did two years ago—jumped on the emails hacked from the Climatic Research Unit as Britain’s East Anglia University, claiming that they show a conspiracy to hide the lack of evidence for global warming.

That’s wrong—not that they’ll ever change their mind—and to my eye and others, the emails do little to change the overarching conclusion that the climate is warming, that much of the warming is due to manmade carbon emissions and that warming poses very serious dangers to the planet and the human race. It’s not a hoax and it’s not a lie—climate change is real.

But that doesn’t mean that climate science—or climate solutions—is anywhere near as fully formed and final as some researchers and advocates like to make it out to be. Newsflash: predicting the future is really hard, and trying to predict how something as complicated as the climate system will change in the future—without even being able to be sure of how inputs into that system like carbon emissions will change—is really, really hard. It could turn out that the climate system is much more sensitive to carbon buildup than we’ve thought—as some scientists have suggested—and that a doubling of the carbon in the atmosphere from pre-industrial times could lead to a temperature increase of as much as 10 C over the next century, which would mean an altogether different planet. Or it’s possible that the climate system may be more resistant to carbon than we think, and warming could proceed relatively slowly. The Intergovernmental Panel on Climate Change, for its part, has estimated that temperatures would rise by about 3 C after a doubling of carbon concentrations.

What this means is that it’s not quite true when environmental advocates say that the “science is settled,” as Al Gore has. The basics absolutely—but beyond that, there’s a whole lot of science left to do, as a new paper shows.

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In this week’s Science, researchers led by Andreas Schmittner of Oregon State University looked at how the Earth’s climate reacted to changing conditions in the past, and they’ve come up with a surprising conclusion. It turns out that the climate system may be less sensitive—and therefore slower to warm—than the IPCC has predicted. That means the scariest predictions of near-double digit warming by the end of the century would be unlikely, buying us more time to slow the growth of carbon emissions and shift the world to a more sustainable energy economy.

Here’s how the study worked. Schmittner and his co-authors compiled land and ocean surface temperature reconstructions from the peak of the last Ice Age 21,000 years ago—a period known as the Last Glacial Maximum (which sort of sounds like a Tugg Speedman picture). At this point, atmospheric CO2 concentrations were about a third less than they were before the Industrial Revolution—the moment when humanity began burning coal and pouring carbon into the atmosphere—and levels of other greenhouse gases were also much lower. Most of the northern latitudes were covered in ice—and because of that, sea levels were significantly lower.

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Schmittner’s model showed less cooling during the Ice Age than most previous studies had, which indicates that the climate system then was less sensitive to atmospheric carbon than expected. One example from the paper: models that assume the system would react violently to additional carbon, leading to very rapid warming, would conversely mean that the entire planet would have been covered in glaciers during the last Ice Age, when carbon concentrations were so low. Obviously that didn’t happen.

The upshot here is that Schmittner’s model suggests that a doubling of the atmosphere’s carbon concentration would lead to a warming of about 2.4 C—still pretty hot, but less apocalyptic than we might fear. From Schmittner:

Many previous climate sensitivity studies have looked at the past only from 1850 through today, and not fully integrated paleoclimate date, especially on a global scale. When you reconstruct sea and land surface temperatures from the peak of the last Ice Age 21,000 years ago – which is referred to as the Last Glacial Maximum – and compare it with climate model simulations of that period, you get a much different picture.

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It’s very important to note—as Schmittner himself does—that this study does nothing to change the basics of climate science, and it still predicts a level of warming that could be very dangerous. And like any climate model—especially one that depends on the reconstruction of past data through ice cores, bore holes and fossils—it’s uncertain as well, and could be understating the threat from climate change.

But given how often we’re reporting dire climate news on this blog, I’m thankful on Thanksgiving for a study that indicates we may have a little more time to save ourselves. And climate skeptics take note: this study, which could dismay the most hysterical climate activists (*see note below), was published in one of the most prestigious journals in the world, not hidden away. (You know, like the way the U.S. Wall Street Journal op-ed page conveniently forgot to publish a piece by the skeptical researcher Richard Muller that confirmed basic tenets of climate science.) Science is far from perfect—see this post from researcher Roger Pielke Jr. on how the hacked emails seem to confirm a concerted effort to keep his work out of the IPCC assessment—but it tends to be considerably more corrective than most other human endeavors. That’s the best truth we can hope for.

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Bryan Walsh is a senior writer at TIME. Find him on Twitter at @bryanrwalsh. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME

*Note: The original post linked to Climate Progress here. I changed because while we may disagree over certain aspects of climate reporting, I generally try to steer clear of loaded language. You can see the Climate Progress take on this paper here, and the Real Climate take here.

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