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Human-caused climate change is the driving force behind the Arctic transitioning into an entirely different climate, according to a new study by scientists at Boulder’s National Center for Atmospheric Research.

Three charts illustrate changes in the Arctic that demonstrate the area is transitioning into a new climate type. (Simmi Sinha / Courtesy of UCAR)

There is already less sea ice and warmer temperatures than the normal range of the Arctic’s previous climate, and research predicts that the number of rainy days will exceed the previous normal range by the middle of this century.

Lead study author Laura Landrum and co-author Marika Holland studied 249 Arctic climate simulations, looking back to 1940 and forward to 2100, to gather data on what a “normal” range is for different indicators like fall and winter air temperature, number of rainy days and the minimum sea ice extent, which is when sea ice reaches its lowest point every year. Both scientists work at NCAR, a research institute in Boulder funded by the National Science Foundation.

While it’s normal to see year-to-year variations in colder or warmer winters, longer or shorter seasons of rain rather than snow and more or less sea ice, the research shows that the Arctic is fast approaching or has already gone beyond those normal variations — hence, a new climate.

Landrum said the study results, published this week in the journal “Nature Climate Change,” are a cause for concern.

“I think the Arctic is a little like the canary in the mine for climate change. The changes in the Arctic are happening very rapidly and dramatically and are very alarming,” Landrum said.

If the Arctic has seen record low levels of sea ice every year for more than a decade, Landrum said, at what point does that stop being the extreme and become the new normal?

“The sea ice has already changed so much and so rapidly that it’s not in the same climate. It’s a different climate regime than it was even in the satellite era (1980s,) which is remarkable,” Landrum said.

The simulations studied by Landrum and Holland also found that if high levels of greenhouse gas emissions persist, the Arctic could be without any ice for months at a time by the end of the century.

Less sea ice feeds into the cycle of warming because of a process called Arctic amplification, Landrum and Holland wrote. Light-colored sea ice reflects light back into space, whereas darker ocean water traps heat. There’s also less ice insulating the sea to maintain cooler temperatures.

The study found that air temperatures in the Arctic will transition into a new climate by the middle of the century. There will also be dramatically more rain and less snow, increasing by 20-60 rainy days by mid-century and 60-90 rainy days by the end of the century.

The impacts of a new Arctic climate are wide-ranging, Landrum said, from water resource management to infrastructure and flood planning.

Increased rains have already caused mass die-offs of Arctic animals. That’s because rain freezes into a sheet of ice that blocks off access to food on the ground, and the animals die of starvation.

“For people and animals living in the Arctic, climate change is not something happening in the future. It’s here and it’s now,” Landrum said.

There is some hope to change the severity of the Arctic’s warming, Landrum said. While the loss of sea ice has already occurred, reduced greenhouse gas emissions could delay the rising temperatures.

“A change in our emissions, like abiding by the Paris Climate Accord, could have a dramatic impact on Arctic climate,” Landrum said. “We have an opportunity to reduce emissions and I know reduction can have a significant impact on climate — but exactly by how much, we can’t say.”

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