The First Arctic Summer Without Ice Is Coming in Just 15 Years

 

There’s a standard image of the Earth as seen from space that we carry in our heads: vast blue seas, green bands of forests, and frozen white caps on the top and bottom. By the summer of 2035, it may not be accurate. Scientists estimate that in just 15 years Arctic summer sea-ice could disappear for the first time since primitive humans left Africa. 

“The point is, this is happening soon,” says Maria-Vittoria Guarino, an Earth system modeler at the British Antarctic Survey and lead author of a study published earlier this month in the journal Nature Climate Change. “We will have less and less time to get ready for it, or less time to act upon it if we want to do something about it.”

The new research is the latest in a steady stream that has moved up the predicted timeframe for the ice-free Arctic milestone. The amount of sea-ice floating atop the Arctic Ocean at summer’s end has fallen about 13% per decade since 1979. The 13 years with the smallest ice extents on record have all happened over the previous 13 years—and this summer is a sure bet to be No. 14. 

The 2035 estimate made by Guarino and her colleagues is based on what’s known about past climates. Scientists over the years have assembled evidence about previous eras from chemical traces in ice, rocks, and sediment. The new Arctic study looks specifically at a period 130,000 years ago, called the Last Interglacial. 

That period was 4° Celsius hotter than than the pre-industrial era—a plausible preview of conditions humans are creating for the future. Current warming on average is already around 1°C, and the Arctic is warming more than twice as fast as the rest of the planet.

Guarino’s research joins a debate about the pace of global heating that has drawn in climate scientists this year. Some newly updated models, like the one Guarino’s team used, now suggest that warming will occur much, much faster than previously thought. There remains disagreement among scientists over modeling results that show accelerated warming. But, as Guarino sees it, the fact that at least one of these models with hotter-than-expected results has successfully matched physical evidence from the Last Interglacial period makes it difficult to dismiss the findings. Earlier climate models struggled to match the geological evidence from the Last Interglacial.

Estimates like these come with lots of uncertainty, which leaves open the possibility that ice may stick around longer, according to Zachary Labe, a postdoctoral researcher in Atmospheric Sciences at Colorado State University. “I’m also hesitant to focus on the year 2035 too much,” he says. “It’s challenging to predict the first ice-free Arctic.”

Scientists from North Carolina State University and the U.S. National Oceanic and Atmospheric Administration earlier this year used a different model to arrive at a similar 2035 target for the ice-free Arctic summer. By “ice-free,” scientists usually mean an extent of less than 1 million square-kilometers. The lowest it has reached is 3.4 million km² in 2012.

Ge Peng, research scholar on the North Carolina State University team, also noted that unexpected events could alter the timeline. The eruption of a large volcano, which spews chemicals into the atmosphere that block sunlight and lower temperatures, could push the estimates out a few years. 

Whichever summer is the first to lose its sea ice, Peng and her colleagues warn that businesses, governments, and people living in the Arctic need to prepare now for changes in regional geopolitics, transportation, and food availability.

Once the pandemic has lifted, Peng hopes to travel to the still-frozen Arctic and find it the way we imagine it with our eyes closed. “I want to do that soon,” she says, “because I don’t want the sea ice to be gone by the time I take the cruise.”

bloomberg.com