After years of warning, sea ice coverage and other indicators are beginning to push outside the bounds of the former “normal” climate.
Scientists often speak of a “new Arctic” to describe the region’s rapidly changing landscape. Temperatures are skyrocketing, sea ice is dwindling and many experts believe the far north is quickly transforming into something unrecognizable.
This week, new research confirms that a new Arctic climate system is, indeed, emerging.
In fact, some aspects of the Arctic climate have already changed beyond anything the region has experienced in the past century. Sea ice extent has shrunk by 31% since the satellite record began in 1979. Patterns in ice coverage today have dropped beyond the bounds of anything that would have been possible just a few decades ago.
By the end of the century, if global temperatures continue to rise unchecked, other key elements of the Arctic climate—including air temperatures and precipitation patterns—could also be profoundly different from the former 20th-century “normal.”
Study co-authors Laura Landrum and Marika Holland, researchers at the National Center for Atmospheric Research in Colorado, published their findings yesterday in the journal Nature Climate Change. The study, they say, is among the first to examine the timing of the emerging new Arctic—the point at which climate conditions fall outside even the furthest boundaries of what was previously “normal”—across both sea and land.
“The changes are so rapid and so large that the Arctic [has] warmed so significantly that its year-to-year variability is moving outside the bounds of past fluctuations, signaling a transition to a new climate,” Landrum told E&E News.
Landrum and Holland used large ensembles of climate models to investigate how the Arctic climate has changed over the last century and what kinds of changes may be in store over the next 100 years. Looking into the future, they focused on a severe hypothetical climate scenario—a trajectory many scientists think of as the worst-case scenario if human societies do nothing to curb their greenhouse gas emissions.
The researchers specifically examined changes in Arctic sea ice extent, air temperatures and precipitation patterns.
Sea ice, they found, has already declined beyond the bounds of anything that would have been seen even a few decades ago. In other words, at least one signal of the new Arctic—driven by climate change—has already emerged.
And sea ice declines will only get worse as time goes on. Under the extreme climate scenario, summer sea ice extent will fall below 1 million square kilometers—a threshold so low most scientists consider the Arctic Ocean “ice free” at that point—by the 2070s at the latest, and potentially decades earlier.
Air temperatures are likely to cross the threshold by the middle of this century, with fall temperatures changing the fastest. Changes in precipitation—namely, a transition from snow to rain—will represent a new Arctic shortly afterward.
That makes sense, considering the way different aspects of the Arctic climate system are linked.
Sea ice can have a profound effect on Arctic temperatures. Ice has a bright, reflective surface that helps beam sunlight away from the Earth. Thick sea ice also helps insulate the ocean, trapping heat below the surface in the winter and preventing it from escaping into the cold Arctic air.
As sea ice thins and disappears, the ocean is able to absorb more heat in the summer. And in the winter, that heat is able to escape through the thinner ice and warm up the atmosphere.
“You would expect ice to play a role in warming the temperature because of these feedbacks,” Landrum said.
The rising temperatures, in turn, help speed up the transition from snow to rain.
The findings confirm that a new Arctic is already emerging—and that if global temperatures keep rising at their current pace, the transformation to an unrecognizable climate system could be complete before the end of this century.
It’s a clear sign that climate change isn’t a problem for the future—it’s already dramatically reshaping the planet today. It’s also a huge concern for the Arctic ecosystem and the human communities that rely on it.
A new Arctic will be warmer, rainier and substantially less frozen. Animals that used to be common may disappear, while new species may move in to take their place. Opportunities for hunting and fishing by sea ice could dwindle. Shipping in the Arctic Ocean may significantly increase as the ice disappears.
Meanwhile, planning for disasters may be an increasingly difficult task.
Community planners often design infrastructure, made to last a certain number of years or withstand a certain level of stress, by looking at past weather observations. But as the Arctic climate transforms, the past is no longer a good predictor of what to expect in the future.
“We’re entering a period where the previous observations we have do not and cannot describe the time that we’re entering,” Landrum said.
While the study provides a grim snapshot of a possible future, it’s not necessarily inevitable. Other studies have indicated that a more moderate climate scenario—one in which world nations substantially reduce greenhouse gas emissions in the coming decades—could stall or prevent some of these changes.
But the research does demonstrate that immediate action is needed.
“For those living in the Arctic—whether it’s human, animal, plant—climate change is not something in the future,” Landrum said. “It’s something that’s happening now.”Link to the original