All the extra warmth of summer is also trapped in the Arctic Ocean, then released during winter. “The greatest warming in the Arctic is happening in the winter, which might surprise people, because you have the greatest amount of sea ice melt in the summer,” said Hahn, of the University of Washington. “That’s when you have sunlight coming in. But the idea is to have the ocean’s seasonal heat storage.” It’s like a giant radiator that heats a room even when it’s turned off.
At the same time, storms have transported moisture from lower latitudes into the Arctic, encouraging the growth of clouds. And pump warmer water from the south, carried north by ocean currents, melt sea ice. “As it melts, the water evaporates and increases atmospheric humidity, which causes an increase in winter haze and we have infrared radiation from these clouds reaching the surface,” Chylek said. “This is a feedback loop that can cause Arctic temperatures to rise, and we believe that’s one of the reasons why we see this temperature rise around 2000.”
University of Washington climate scientist Cecilia Bitz, who studies Arctic amplification but was not involved in the new study, points out that there is a lag in how regions at high latitudes respond to the climate. greenhouse compared to the rest of the planet. It took time for sea ice to melt, but now that it’s doing so, the Arctic heat feedback loop has gotten worse and the rate of change has become much more noticeable. “First, the tropics are warming faster, and now the poles are catching up, and that’s why you see a trend,” she said.
The consequences have been huge and far-reaching. First and foremost, more melting — especially in Greenland, which is losing quarter trillion tons ice every year — which means higher sea level. In addition, warmer waters become physically larger, a phenomenon is called thermal expansioncontinue to raise sea level.
The landscape is also undergoing literal and metaphorical upheaval. Warming temperatures are thawing frozen soil known as permafrost. When that permafrost loses water, it collapses, pull down any infrastructure in or on it, like pipes, roads and buildings. “Have Everyone in the Arctic,” said Bitz. “They have done little to deserve to live in this dangerous environment.”
Soaring temperatures are also greening that landscape. Shrub species are moving north, and more snowy vegetation is on the ground. This prevents the cold of winter from entering it, potentially accelerate the thawing of permafrost. All that extra vegetation is also darker – in the same way the sea itself is darker than its ice – and so absorbs more of the sun’s radiation.
Simply put, the Arctic is in a state of climate and ecological instability. Isla Myers-Smith, a global change ecologist at the University of Edinburgh who was not involved in the new study, said: “Every summer that my field team goes to the North Pole, we I don’t know what I will do. “This year we went to Inuvik, Canada, in a thermal dome with temperatures up to 32 degrees Celsius [90 degrees Fahrenheit]but off the coast there is still a lot of sea ice around, keeping local temperatures much cooler. “
This type of variation makes it difficult for models to determine how the Arctic is changing and to predict how those changes will play out to affect the larger climate system. That’s why it’s important for scientists to rethink their understanding that the Arctic is actually warming more. four times as fast as the rest of the planet.
A key concern is the potential for the climate system to reach a tipping point, where warming initiates rapid change. For example, if the Arctic is warm enough, melting in Greenland could rapidly accelerate. “I don’t think it’s really known exactly – if these cut-off points exist – the extent,” said Michael Previdi, a climate scientist at Columbia University’s Lamont-Doherty Earth Observatory. What kind of warming would cause such rapid changes?” related to new articles. However, he continued, a larger gain in theory “increases the chance of overcoming one of these cut-off points”.
