If you’re not worried about global warming yet, read this new report by National Geographic Daily News on the melting of the Arctic icecaps. It’s a special problem for the magazine, which is famous for its maps. How do you draw an icecap that keeps changing in the definitive atlas, National Geographic’s Atlas of the World?
Here’s their solution, as implemented in the alarming drawings below:
The multiyear ice—or older ice—is shown on the map as a large white mass; the maximum extent of sea ice—the pack ice that melts and refreezes with the seasons—is depicted as a line on the map, according to Rosemary Wardley, National Geographic’s senior GIS cartographer. In the 10th edition, which will be released September 30, the multiyear ice is much smaller in area than on previous maps. The 5th edition of the atlas, published in 1989, was the first to comprehensively map the Arctic.
Wardley and Valdés relied on two government resources that track Arctic ice data: NASA and the NSIDC. To map the multiyear ice, they took data from a 30-year study by NASA, published in 2012. “We wanted to have that comprehensive coverage,” Wardley said.
Well, look and weep: here’s the change in the last 18 years.
And, of course, the why:
As the ocean heats up due to global warming, Arctic sea ice has been locked in a downward spiral.Since the late 1970s, the ice has retreated by 12 percent per decade, worsening after 2007, according to NASA. May 2014 represented the third lowest extent of sea ice during that month in the satellite record,according to the National Snow and Ice Data Center (NSIDC).
Ice loss is accelerated in the Arctic because of a phenomenon known as the feedback loop: Thin ice is less reflective than thick ice, allowing more sunlight to be absorbed by the ocean, which in turn weakens the ice and warms the ocean even more, NASA says.
Because thinner ice is flatter, it allows melt ponds to accumulate on the surface, reducing the reflectiveness of the ice and absorbing more heat. (See pictures of our melting world in National Geographicmagazine.)
“You hear reports all the time in the media about this,” Valdés said. “Until you have a hard-copy map in your hand, the message doesn’t really hit home.”
Some scientists argue that the map is a bit misleading (but not that it doesn’t reflect global warming); but you’ll have to go to the original article to read about that.