National Geographic comes out with a new world atlas about twice a decade, as mapmakers struggle to stay up to date with things like shifting political borders and ballooning populations. But when the latest edition of the National Geographic Atlas of the World is published this fall, the most obvious change will be environmental: The shrinking sea ice in the Arctic Ocean, which the cartographer leading the project calls "the biggest visible change other than the breakup of the U.S.S.R."
Arctic ice—especially the "multi-year" ice that stays frozen for at least two summers—has been slowly disappearing over the last few decades, and more quickly since 2007. In 2012, when the data was gathered for the new version of the atlas, the ice had shrunk to the smallest size ever on record.
Mapping the ice isn’t easy, since the size is constantly changing. Next to the older ice, a layer of new ice freezes and expands each winter and shrinks in the summer. To stay consistent with older versions of the atlas, the mapmakers chose to show the ice as it looked in the spring of 2012, before even more had melted in the warmer weather. A line traces along the edge of the older ice.
They didn’t include the ice as it looked at the end of the summer. "There is only so much information we can put on the map before it becomes confusing to the user," says Rosemary Wardley, senior GIS cartographer. "This is a constant struggle that a cartographer has to face, deciding which information to show and which to leave out."
Print has other obvious limitations—long production and printing schedules mean that data can quickly go out of date, and that’s automatically the case with something dynamic like sea ice. There isn’t necessarily space to show comparisons of what ice looked like in the past, unlike online tools.
But the team behind the atlas thinks that there’s something unique about holding a physical map that might have more of an effect than reading yet another article about the changing sea ice. "An atlas provides a historical snapshot of a certain area over an extended period of time," says Wardley. "We hope that the information we show will stoke the curiosity of the map reader and encourage them to look further into the subject."
[Image: Courtesy of National Geographic]