“When I first started working in the central Arctic, most of the ice was nearly twice my height,” says Stephanie Pfirman, a 5'7" professor of environmental science at Barnard College and Columbia University. She has been studying Arctic sea ice for more than 30 years, starting with a 1980 expedition to Svalbard—a remote, northern Norwegian archipelago. In the 1980s, the average sea ice thickness in the central Arctic was about 10 feet. “Now,” Pfirman says, “it is basically down to my height.”
In September 2012, the extent of sea ice hit a record low after a particularly hot summer: 1.32 million square miles, 44% below the 1981–2010 average. And from mid-October to late November 2016, the extent of Arctic sea ice was the lowest since the satellite record began in 1979. Ice sheets on land are melting at an accelerating pace, as well, contributing directly to sea-level rise, a growing threat for coastal cities and communities worldwide.
In fact, changes occurring in the Arctic are affecting the entire planet in a profound way. As sea ice retreats and land ice melts, sunlight that would have been reflected back to space by the bright ice is instead absorbed by the ocean, warming the water and melting even more ice.
Moreover, at least 1,500 billion tons of organic carbon have been safely locked away in the frozen soils of the Arctic for thousands of years—almost twice as much as is currently in the atmosphere. As this permafrost thaws, the carbon breaks down, releasing greenhouse gases into the atmosphere and amplifying global warming.
It is now increasingly evident that Arctic warming influences weather in the more temperate zones—the mid-latitudes between the poles and the equator— where the vast majority of humanity lives. As the Arctic warms, the difference between Arctic temperatures and those of the lower latitudes is shrinking. But that temperature differential is what fuels and guides the jet stream, the fast-moving river of air high in the atmosphere that drives our weather. A weaker and “wavier” jet stream promotes more persistent weather patterns in the Northern atmosphere, which can lead to extreme, long-lasting droughts, cold spells, heat waves, flooding, and snowy winters in North America, Asia, and Europe.
“This is just one example of how the impact of a very warm Arctic is going to be felt,” says Jennifer Francis, a professor of atmospheric sciences at Rutgers University. “It’s about making weather patterns hang around longer, and this tends to lead to extreme weather events.”
“Changes in the climate system are not going to happen only in the distant future. They are already happening and affecting us,” says Francis. “We need to start doing something about it, because these impacts are big.”