arcticThe last four decades have borne witness to both NASA’s improving satellite technology and the steady decline of Arctic sea ice. For NASA, the former has been gradually revealing the latter. 

In two videos recently released to the public, NASA traces the origins of Arctic exploration through the 20th century and into the first decades of the current one. As NASA’s satellite technology has developed, so too has its ability to follow the trends of the Arctic’s winter growths and summer melts.

In the 1980s, a general lessening of Arctic ice seemed to be occurring. However, the imaging technology of the time was still developing and the ice cover it documented remained within an acceptable range of seasonal variability. After all, NASA’s very first instruments could not even see through clouds, and it wasn’t until 1978 that microwave instruments enabled the agency to distinguish between young and old ice.

It would not be until 2003 that ice thickness could be measured using a laser altimeter, but by that time it was clear that the Arctic was losing its ice cover at almost 3 percent per year.

In 1999, Claire Parkinson and others at NASA Goddard published a report that included all of the visual satellite data of the last 20 years. What they were uncertain of in 1989 became much clearer by the end of the century.

“We couldn’t be sure, with such a short record, the interannual variability in the ice cover, and such a small trend toward decreasing ice coverage,” said Parkinson. “But the decrease we saw certainly was enough to alert us to the fact that we should keep up this record and continue to monitor the changes.”

Not only was Arctic ice retreating at 2.8 percent per decade, the trend was negative in every season, through winter growths and summer melts. In 2005, Arctic sea ice shrank by 194,000 square miles.

“At that point it seemed like a fairly dramatic record low. That’s when it seemed that, yes, the decline might be going a little faster than we thought it was capable of going,” said Walt Meier, a research scientist at NASA Goddard. “And then in 2007, the bottom seemed to fall out.”

In 2007, Arctic ice contracted from 2.16 million square miles to 1.66 million square miles. As NASA writes, “compared to the average summer sea ice extent from 1979 to 2006, the Arctic Ocean had lost a chunk of its sea ice cover equivalent to the combined size of Alaska and Texas.”

“There was a lot of shock in the sea ice community,” said Meier. “I don’t remember anyone thinking it could get that low that quickly.”

Today, along with the Arctic, Greenland and Antarctica are melting at an “unprecedented rate.” Laser altimeters have revealed that the ice is losing thickness as well as cover, a likely result of warming seas heating the ice from below. In the future, this could mean that Arctic and Antarctic ice may melt faster than previously believed and contribute to dangerous sea level rise across the globe.

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