NOAA releases 2015 Arctic report card
Temperatures are warmer, snow is melting sooner and more extensively, and sea and land ice are diminishing. Those are some of the findings in this year's Arctic Report Card, released last week by the National Oceanic and Atmospheric Administration.
The report card is a comprehensive summary of observed conditions in the global northern ecosystem that's released annually.
While the report outlines a number of changes and changing trends in the system, it lists retreating sea ice as the "most pervasive threat to ice-associated marine mammals, including walruses."
According to data, the minimum sea ice extent observed this September was 29 percent less than the averages measured between 1981 and 2010. It was also the fourth lowest recorded since satellite measurements began in 1979.
The lowest maximum sea ice extent ever recorded also occurred this spring at seven percent less than the average since 1981. Not only did the ice retreat faster and earlier than usual, it was of a different makeup than it has been over the past 30 years.
In 1985, ice older than four years made up 20 percent of the pack ice and 35 percent was first-year ice. In February and March of this year, old ice made up only three percent compared to 70 percent new.
All of these figures spell out an uncertain future for marine mammals who depend on sea ice for their ways of life.
Walruses in the Pacific Arctic, like Alaska, have been observed traveling long distances to haul out on land rather than on nearby sea ice as they would have in the past. That's in part due to the fact that there's simply less ice than there has been and consequently, the ice has a lower carrying capacity for walruses than it used to.
The diminishing ice has serious consequences for other facets of the ecosystem as well. With less protective ice cover in the sunny summer months, sea surface temperatures have been on the rise in recent years with the Chukchi Sea demonstrating one of the most severe warming trends—a steady increase of half a degree Centigrade per decade—since 1982, with spikes in that temperature happening periodically.
Arctic snow cover, or the amount of snow on the ground during certain parts of the year, has also been on the decline recently. Snow has been melting earlier in the year over the past decade, leading to longer, browner summer-weather months. Snow cover this June was the second lowest on record since 1979; there's been an 18 percent decline in June snow cover per decade measured since then as well.
Another indicator in the report, aside from marine mammals, is the annual discharge of Arctic rivers, meaning the release of fresh water into surrounding environments that can drastically change the biology, chemistry, and circulation of coastal and ocean ecosystems. There has been much more significant discharge over the past two years than in years past.
With regard to air temperature, over the past year, temperatures have consistently been recorded at more than one degree Centigrade, or more than two degrees Fahrenheit, above average since the start of the 20th century.
The amount of vegetation, or greenery, on land is also shifting and certain parts of the state have experienced surface "browning" in recent years, like the Yukon Kuskokwim delta region, which can have consequences for land mammals, birds, and more in the long run.
While the precise implications of these observed changes isn't entirely known yet, what is known is that the Arctic ecosystem is not what it used to be and additional shifts are sure to come in the near future.
To read the entire 2015 Arctic Report Card, visit arctic.noaa.gov.