Rate of Glacial Melting Is Accelerating, Comprehensive Study Finds
For scientists who study climate change, it’s no longer a question of whether or not human activity is affecting the planet. It’s a question of how much we’re wrecking the only place we call home. According to a new study from a French-led team, things aren’t going great. The researchers found that the rate of ice loss from glaciers has accelerated for the first two decades of the 21st century, and there’s every reason to expect that trend will continue.
The team is confident in its measurements because it was able to use the same methodology to analyze every significant glacial ice stream. In 1999, NASA launched the Terra climate satellite, and it’s been up there taking pictures ever since. Using powerful computers, the team was able to interpret Terra’s images to measure yearly changes in glacial elevation and mass. The researchers believe the numbers reported in the study, published in the prestigious journal Nature, are accurate to within five percent.
There are currently 217,175 ice streams associated with the world’s glaciers. Some are the size of a city block, and others cover many square miles. The one thing they all have in common is the volume of water is increasing. The results of this analysis are grim—the world’s glaciers are losing 267 gigatonnes (metric) or 297 gigatons (imperial). No matter your preferred measurement scale, that’s a lot of ice melt.
The overall ice loss is staggering, but that’s not even the worst news. The team reports that the rate of loss has accelerated during the last 20 years. From 2000 to 2004, the Earth’s glaciers collectively lost 227 gigatonnes of ice each year. By 2015, that number had jumped to about 298 gigatonnes (billions of tonnes). A single gigatonne of ice would cover more than 50 city blocks to a depth of about 1,100 feet. And 300 of those are melting every year now.
Glaciers have faster response times to climate change compared with the ice sheets in Greenland and Antarctica. Currently, the accelerated melting of glaciers is contributing more to sea level rise than ice sheets, but that may not be true forever. Even small changes in ice sheets, which we have already started to see, can lead to much greater sea level increases.
The study was not focused on the causes of climate change. Plenty of papers have expounded on the various ways in which humans are to blame, though. As emissions increase across the globe, the trend of faster melting will most likely continue. Even radical shifts in human activity will take time to bring climate change under control. By some measurements, it’s already too late to avoid major consequences of climate change.
Top image credit: Luca Galuzzi/CC BY-SA 2.5
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