Perhaps you've heard about the death of climate change. "Antarctica is actually gaining ice," says NASA. "Is global warming over?" asks one headline writer. Not quite, goes the inevitable hedge.
Well...yes. But no. Climate change is depressingly robust. The new study—published October 30 in the Journal of Glaciology—offers no evidence that the planet's temperature has returned to pre-1860s levels. Atmospheric carbon dioxide has not dropped below 250 parts per million. Sea levels have not receded. What has happened is that some parts of Antarctica are (maybe) freezing faster than other parts are melting.
About which, hooray! If the study is correct in its assessment of Antarctica's freeze, that is. Some climate scientists say the study itself might be flawed.
Antarctica is losing ice, mostly from its western ice sheets. This new study says that accumulation in the continent's interior is offsetting that progressive sloughing, for a net gain of about 100 billion tons of ice per year (though it has been slowing in recent years). "The other point is that the gain of ice is taking out about a quarter of a millimeter per year from sea level rise," says Jay Zwally, chief cryospheric scientist at NASA's Goddard Space Flight Center in Maryland and lead author of the study.
That's fine, but it doesn't mean the climate isn't changing. Zwally himself points out that if Antarctica is gaining more ice, then somewhere else in the world is melting faster—because scientists have pretty good data showing that sea levels have been rising at a rate of about three millimeters a year for the past 100 years.
More than that, though, Zwelly used data from satellites that weren't built to measure changes in ice in such fine detail. "He's trying to do two things that require a lot of accuracy: Estimate how ice compresses as it falls, and how much the ice sheet is thickening and thinning," says Benjamin Smith, a geophysicist at the University of Washington's Applied Physics Laboratory. "It's not necessarily the case that he has the wrong answer, but it's also hard to say with any certainty that he has the right answer."
Ted Scambos, senior research scientist at the National Snow and Ice Data Center in Boulder put his criticism more bluntly: "What I would really hope is that you do not publicize this paper at all."
If true, Zwelly's results would refute findings—and methodology—used in the Intergovernmental Panel on Climate Change's 2013 assessment, currently the baseline for all other climate change research. Rather than measure ice height, the IPCC report used gravity-sensing satellites to add up the total mass of ice and the rock below. "When you factor out what the rock is doing, you see that the ice sheet is losing mass," says Smith. But, again, that would leave a gap in the budget of water sources that have contributed to sea level rise.
Right or wrong, Zwelly's study says little about climate change as a whole. In fact, equating Antarctic ice gain to the death of global warming is about as accurate as saying that racism in America ended the day Barack Obama took office.
