Arctic sea ice levels were at the lowest winter maximum on record this year, but that's only part of the story. The ice is also a lot thinner than it used to be, experts say.
"The sea ice cover is really pretty thin," Walter Meier of the NASA Goddard Space Flight Center said. "That's another big part of the story."
"It's not just the extent; the area covered is less and less, but the ice is getting thinner, too," he said.
NASA reported in March that the Arctic sea ice cover reached its lowest winter maximum levels ever recorded. According to Meier, the last three winters--back to 2015--have been the lowest levels recorded since satellite data was recorded in 1979.
While the amount of ice coverage in the Arctic has drastically waned in recent years, the thickness of the ice has dropped too.
"Normally, the ice cover in the Arctic back in the 1980s would be 3 to 4 meters (about 10 to 13 feet) thick," Meier said. "Most of the Arctic now is 1 to 2 meters (about 3 to 7 feet) thick. That's a pretty big change."
While there is no one sole factor that leads to the thinning, receding ice, the main driving force behind the warmer Arctic is greenhouse gases, including carbon dioxide.
"Sea ice is pretty sensitive to temperatures, and therefore pretty sensitive to the ultimate driver in the long term: greenhouse gas emissions," Meier said. "What that means is that it's sensitive in the other direction too."
#IceBridge flew up Verhoeff Glacier (NW Greenland) on 4/7. This video takes us from near the glacier’s calving front to the ice sheet. pic.twitter.com/hX9CDvtieJ
— NASA ICE (@NASA_ICE) April 12, 2017
Meier said that by globally reducing greenhouse gases in the air, the Arctic ice would make a comeback.
"If emissions are stabilized or reduced, the trend and loss of ice will slow down and eventually stop, and eventually reverse," Meier said. "If it goes low enough, it can build back the thicker ice fairly quickly, within five or 10 years."
While the data on Arctic ice thickness isn't as up to snuff as the data on the ice coverage, NASA is working on multiple projects to gather more evidence. Operation Ice Bridge flies over the Arctic once a year to collect data and observations from the area. NASA is also planning on launching another satellite called ICESat- 2 next year. Both of these projects will be able to measure the thickness of the ice from above.
The loss of sea ice is just one effect of the increasingly warmer Arctic, which Meier said is warmer at a rate 2 to 3 times faster than the rest of the planet on average. The change in temperatures at the poles can have a larger effect on all parts of the globe.
"The climate system's interconnected," Meier said. "So what happens in the Arctic doesn't stay in the Arctic."