Dec 4, 2019 2:00 PM

The Arctic Is Warming Much Faster Than the Rest of Earth

Rising temperatures in the northern polar cap are driving extreme heat, drought, and sea level rise in the continental US, a study says.

As climate delegates discuss the planet’s future at the COP25 meeting in Madrid this week, a new study finds the Arctic is warming much faster than the rest of the planet. That’s forcing polar bears and walruses to crowd onto shrinking beaches, starving reindeer and caribou, and driving extreme heat, drought, and sea level rise along the US coast.

Those are some of the results of a new study published today in the journal Science Advances that reports the Arctic has warmed by 0.75 degrees Celsius (1.35 degrees Fahrenheit) in the last decade alone. By comparison, Earth as a whole has warmed by nearly the same amount, 0.8 degrees C, over the past 137 years.

Under a “business as usual” scenario of industrial emissions that continue at their current rate, the report’s authors say the Arctic Ocean will be ice-free in 20 years. By the end of the century, Arctic temperatures will jump a whopping 13 degrees C (23.4 degrees F) during the fall months, when sea ice is at a minimum.

A warming Arctic has consequences for the entire planet, including residents of the United States, according to a panel of 15 climate, oceanography, and wildlife experts from the US, UK, and Europe who contributed to the study.

Previous reports have looked at individual aspects of climate change in the polar region, but this was a collaborative effort to examine multiple scientific disciplines to give an updated look at what’s happening and what lies in store in the coming decades.

Kristin Laidre, an animal ecologist at the University of Washington and a coauthor, says the melting summer sea ice is causing trouble for big mammals: polar bears, walruses, and seals. She says they are struggling to survive because they can’t hunt, rest, or give birth on floating sea ice.

“They all rely heavily on the sea ice platform for all aspects of their life,” Laidre says. “As we continue to lose ice and see the changes in the ecosystem, we are already seeing big changes and we expect it to continue. There’s no way around that.”

With less sea ice to haul out on, seals and walruses are crowding onto beaches, leading to more trampling deaths of younger animals. Polar bears are swimming longer distances from land to the ice floes where they hunt seals. As the rest of the world’s oceans warm as well, coldwater fish, crustaceans, and plankton are moving north to the Arctic. That brings new diseases, parasites, and other threats to the marine life that already lives there, she says.

Climate change is also affecting land mammals like reindeer and caribou that are the main source of food for indigenous peoples of Canada, Siberia, and other Arctic nations. Reindeer are being decimated by rainfall over ice, which killed tens of thousands of animals in the past decade. In Greenland, botanists are discovering some flowering plants are emerging earlier each year, but not the pollinating insects they rely on.

And then there’s the weather. Michael Mann, a coauthor of the study and a climate scientist at Penn State, says the disappearing sea ice allows the Arctic Ocean to absorb even more sunlight, heating it up even more and melting more ice. “It’s a vicious cycle,” Mann writes in an email.

The accelerated Arctic warming affects weather in the continental US and around the entire Northern Hemisphere by changing the temperature contrast between mid- and high-latitude parts of the globe.

That temperature contrast is responsible for the existence of the jet stream; when the contrast shrinks, the jet stream tends to slow down. Weather systems tend to linger longer in the same location. It can also cause the undulations of the jet stream to grow in amplitude, which leads to more anomalous weather systems, Mann says.

The combination gives us the sort of persistent weather extremes we’ve seen affecting the US and Europe in recent summers, including many of the unprecedented heat waves, floods, droughts, and wildfires. In the winter, it is associated with more frequent outbreaks of freezing Arctic air tied to the breakdown of the so-called polar vortex, something we’ve seen already early this winter in the Midwest and eastern US.

The study finds that Antarctica, by contrast, has not been warming as rapidly as the Arctic. The problem is that when the ice sheets of that continent do begin to melt, the vast amount of meltwater they contain will wreak global havoc.

“You can also think of the Arctic as responding in somewhat cumulative fashion to ongoing warming,” says the study’s lead author, UC Davis climate ecologist Eric Post. “While the Antarctic is more like a system with a big switch that’s about to flip.”

Despite the dire outlook, both Mann and Laidre say they believe that some kind of climate action might be possible to reverse the danger signs. They point to treaties on the ozone hole and Arctic fishing that actually worked, and to climate activism by young people.

“The window of time for us to take action is closing, and we know large-scale, international, coordinated actions are needed to quickly reduce our emissions and use the right energy sources,” Laidre says. “It’s possible, but we need to do it soon.”

On Tuesday, the multinational Global Carbon Project reported that carbon emissions rose .6 percent in 2019, which is slightly less than in the past three years. Scientists say global emissions must be cut in half by 2030 to stop dangerous levels of greenhouse warming. Delegates at the COP25 meeting hope to agree on specifics of how they plan to reach the voluntary carbon reductions they agreed to during the Paris Climate Accord, which goes into effect next year. The White House told UN officials it was withdrawing from the agreement.