Earth’s Land Ice by the Numbers
“At a glacial pace” used to mean moving so slowly the movement is almost imperceptible. Lately though, glaciers are moving faster. Ice on land is melting and flowing, sending water to the oceans, where it raises sea levels.
In 2018, we launched the Ice, Cloud and Land Elevation Satellite-2 (ICESat-2) to continue a global record of ice elevation. Now, the results are in. Using millions of measurements from a laser in space and quite a bit of math, researchers have confirmed that Earth is rapidly losing ice.
ICESat-2 was a follow-up mission to the original ICESat, which launched in 2003 and took measurements until 2009. Comparing the two records tells us how much ice sheets have lost over 16 years.
During those 16 years, melting ice from Antarctica and Greenland was responsible for just over a half-inch of sea level rise. When ice on land melts, it eventually finds its way to the ocean. The rapid melt at the poles is no exception.
400,000 Olympic Swimming Pools
One gigaton of ice holds enough water to fill 400,000 Olympic swimming pools. It’s also enough ice to cover Central Park in New York in more than 1,000 feet of ice.
Between 2003 and 2019, Greenland lost 200 gigatons of ice per year. That’s 80 million Olympic swimming pools reaching the ocean every year, just from Greenland alone.
During the same time period, Antarctica lost 118 gigatons of ice per year. That’s another 47 million Olympic swimming pools every year. While there has been some elevation gain in the continent’s center from increased snowfall, it’s nowhere near enough to make up for how much ice is lost to the sea from coastal glaciers.
ICESat-2 sends out 10,000 pulses of laser light a second down to Earth’s surface and times how long it takes them to return to the satellite, down to a billionth of a second. That’s how we get such precise measurements of height and changing elevation.
These numbers confirm what scientists have been finding in most previous studies and continue a long record of data showing how Earth’s polar ice is melting. ICESat-2 is a key tool in our toolbox to track how our planet is changing.
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