Four male polar bears standing on a floating whale carcass shortly after it drifted to shore on the island of Svalbard. Daniel J. Cox/Arctic Documentary Project
With 2019 on pace as one of the warmest years on record, a new international study reveals how rapidly the Arctic is warming and examines global consequences of continued polar warming.
The study , published Dec. 4 Advances, reports that the Arctic has warmed by 0.75 degrees C in the last decade alone. By comparison, the Earth as a whole has warmed by nearly the same amount, 0.8 C, over the past 137 years.
"Many of the changes over the past decade are so dramatic they make you wonder what the next decade of warming will bring," said lead author Eric Post , a University of California, Davis, professor of climate change ecology. "If we haven’t already entered a new Arctic, we are certainly on the threshold."
What 2 degrees global warming means for the poles
The comprehensive report represents the efforts of an international team of 15 authors, including Kristin Laidre at the University of Washington, who specialize in an array of disciplines, including the life, Earth, social and political sciences. They documented widespread effects of warming in the Arctic and Antarctic on wildlife, traditional human livelihoods, tundra vegetation, methane release, and loss of seaand land-ice.
"What’s happening in the Arctic is profound and unprecedented,” said Laidre, a UW research scientist at the Polar Science Center and associate professor in the School of Aquatic and Fishery Sciences. "Marine mammals rely on the sea ice platform for most aspects of their life and it is rapidly disappearing. This has cascading impacts on the ecosystem, species interactions, and indigenous humans who rely on these animals for nutritional, cultural and economic purposes.”
Laidre served as the team’s expert on Arctic marine mammals, bringing together the recent literature on profound changes observed related to species and populations, and linking them to other physical and biological components catalogued by other co-authors.
The research team also examined consequences for the polar regions as the Earth inches toward 2 C warming, a commonly discussed milestone.
"Under a business-as-usual scenario, the Earth as a whole may reach that milestone in about 40 years," said Post. "But the Arctic is already there during some months of the year, and it could reach 2 C warming on an annual mean basis as soon as 25 years before the rest of the planet."
The study illustrates what 2 C of global warming could mean for the high latitudes: up to 7 C warming for the Arctic and 3 C warming for the Antarctic during some months of the year.
The authors say that active, near-term measures to reduce carbon emissions are crucial to slowing high latitude warming, especially in the Arctic.
Beyond the polar regions
Post emphasizes that major consequences of projected warming in the absence of carbon mitigation are expected to reach beyond the polar regions. Among these are sea level rise resulting from rapid melting of land ice in the Arctic and Antarctic, as well as increased risk of extreme weather, deadly heat waves, and wildfire in parts of the Northern Hemisphere.
"What happens in the Arctic doesn’t stay in the Arctic," said co-author Michael Mann , a distinguished professor of atmospheric sciences at Pennsylvania State University. "The dramatic warming and melting of Arctic ice is impacting the jet stream in a way that gives us more persistent and damaging weather extremes."
The Greenland Ice Sheet in 2008. The ice sheet appears highly sensitive to warming beyond 1 to 4 degrees Celsius beyond pre-Industrial levels. In the decade since this photo was taken, the Arctic has already warmed by 0.75 degrees C. Eric Post/UC Davis
Other co-author institutions are Aarhus University; University of Oxford; University of Lapland; University of Colorado, Boulder; Chicago Botanic Garden; Dartmouth College; Umea University; University College London; U.S. Arctic Research Commission; Harvard University; and National Oceanic and Atmospheric Administration (NOAA).
Tag(s): Applied Physics Laboratory o College of the Environment o Kristin Laidre o Polar Science Center o School of Aquatic and Fishery Sciences