FNASA’s 64 year history has seen agency leaders confront the daunting task of answering the question. what’s-the-point? question. What’s the point, legislators and taxpayers ask, of spending so much money in space when there are so many problems on Earth? NASA always has a ready answer. It points to all the Earth-observing satellites that it launched. These have provided a detailed look at weather and climate conditions, as well as other issues. What the agency has never promised was that we’d like what the satellites tell us.
NASA reported this week that the Earth’s condition has been particularly troubling to their findings from space. In a pair of papers—one published in NatureOne in, one out Earth System Science Data—researchers analyzed 25 years of sightings from a fleet of seven American and European satellites surveying the Antarctic, and had grim tidings. According to the papers, the loss of mass from Antarctica’s ice shelves—or ice that protrudes past the coastline—has been twice as extensive as previously estimated. The data show that 12 million tonnes of ice have been lost since 1997 as opposed to six million originally estimated. “Antarctica is crumbling at its edges,” Chad Greene, a postdoctoral fellow at NASA’s and Caltech’s Jet Propulsion Laboratory and a co-author of the NaturePaper, as stated in a statement
That’s bad news not just for Antarctica, but for the rest of the world. The floating shelves serve as a support for Antarctic ice. As more shelving is removed, more land-based glaciers are also lost. This contributes significantly to rising sea levels.
The satellite measurements techniques used altimeters, not vertical expansion of the ice but horizontal elevation to produce the recently released findings. According to the instruments, the height of the ice has decreased, which indicates that they are being melted by the warmer ocean. This makes them more fragile, thinner and more susceptible to melting. Altimeters were not used until the new two studies to determine this phenomenon across the Antarctic continent. It was difficult for even trained eyes to see satellite imagery and this made it challenging to conduct such an extensive study.
“For example,” said Greene, “you can imagine looking at a satellite image and trying to figure out the difference between a white iceberg, white ice shelf, white sea ice, and even a white cloud. That’s always been a difficult task. But we now have enough data from multiple satellite sensors to see a clear picture of how Antarctica’s coastline has evolved in recent years.”
Worse, in the next few decades the rate of ice shelf loss over the past 25-years will be faster than the previous decade. Even if global warming were to slow, researchers don’t believe the ice shelves can grow back to their pre-2000 reach any time in this century. “Antarctica’s largest ice shelves.” the NASA statement warns, “all appear to be headed for major calving events in the next 10 to 20 years.”
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