The Arctic region caught a break this year, as sea ice melt was significantly less than last year’s record dip. But it’s certainly no reason to doubt the long-term trend, Arctic researchers said at today’s AGU meeting, or that a melting Arctic affects the entire globe.
“The Arctic is not like Vegas,” said Howard E. Epstein of the University of Virginia. “What happens in the Arctic doesn’t stay in the Arctic.”
The National Oceanic and Atmospheric Administration (NOAA) released its annual report on the state of the Arctic, as it has every year since 2006. This year’s report consists of 18 essays written by 147 scientists from 14 different countries, all independently peer reviewed.
Increased cloud cover caused cooler summer temperatures in the Arctic in 2013, leading to a rebound in the September minimum ice extent of 43 percent (JAXA data). “But the relatively cool year in some parts of the Arctic does little to offset the long-term trend of the last 30 years,” said David M. Kennedy, NOAA’s deputy under secretary for operations. “The Arctic is warming rapidly, becoming greener and experiencing a variety of changes, affecting people, the physical environment, and marine and land ecosystems.”
It is also becoming more variable, perhaps due to a more sinuous jet stream created by heat release from unfrozen Arctic waters. Fairbanks, Alaska, just below the Arctic Circle, experienced a record 36 days in 2013 with temperatures at or exceeding 80 degrees F (27 degrees C), while cooler temperatures brought melting of the Greenland ice sheet on up to 44 percent of its surface, close to the long-term average but much smaller than 2012′s record 97 percent.
Despite the relatively cool summer in the Arctic, the September ice minimum was the sixth-lowest since observations began in 1979. The seven lowest recorded sea ice extents have all occurred in the last seven years.
In some regards the Arctic is the cleanest it’s been in decades. Atmospheric soot called “black carbon” has been decreasing across the high Arctic, mostly due to the collapse of the heavily industrialized Soviet Union. But tundra wildfires have increased dramatically, said Epstein, as the region greens.
The increase in vegetation may also be partly responsible for the under prediction of Arctic ice melt by climate models, as plants grow taller and stick above the snow level. Their dark color, compared to highly reflective ice and snow, absorbs more heat, a small-scale feature that climate models cannot easily incorporate.
“Every aspect of Arctic life has the potential to be affected by these changes,” said Kennedy, who once lived and worked in the region 30 years ago. “My own personal observation from then to now is of very significant change.”
But observations in the Arctic have been reduced by the U.S. government’s budget sequestration, said Kathy Crane of NOAA’s Office of Oceanic and Atmospheric Research. Scientists also noted the need for better charts of Arctic ice, as its open water increasingly attracts transport ships, military vessels, and even cruise lines.