The frozen continent of Antarctica holds a lot of ice. Like, a lot of ice. So finding out how much of it is melting into the oceans—raising sea level—and how much will melt in the future is a huge task. Not only do we need comprehensive measurements covering the most remote region on Earth, but even small measurement errors equate to very large differences in total ice mass.
This is largely a job for satellites, and we've got several different types of measurements being made from above, measuring things like ice surface elevation and even the gravitational attraction of the mass of ice. There are complicating issues, though, like the fact that the continent itself is responding to current and past ice loss by slowly rebounding upward. And we still need on-the-ground weather monitoring to track the accumulation of snow, among a host of other things.
Enter the huge collaboration of Antarctic researchers called the IMBIE Project (the Ice Sheet Mass Balance Inter-comparison Exercise). This week, that collaboration published a new analysis of all the available data from dozens of studies, producing an overall best estimate of Antarctic ice loss between 1992 and 2017.The complex, multi-pronged nature of this effort means that researchers frequently publish separate estimates of change based on the type of data they are collecting, rather than integrating all sources of information. These numbers can naturally differ, making it hard to put your finger on one answer.
Jumping straight to that result, IMBIE finds that Antarctica lost 2,720 ± 1,390 gigatons of ice in that time period—enough to raise global sea level 7.6 millimeters on its own. The rate of ice loss has increased, though, averaging about 43 gigatons per year over the first 10 years and rising to 220 gigatons per year in the last 5 years.
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