Arctic shows no sign of returning to reliably frozen region of recent past decades

Despite relatively cool summer temperatures, observations in 2017 continue to indicate that the Arctic environmental system has reached a ‘new normal’, characterized by long-term losses in the extent and thickness of the sea ice cover, the extent and duration of the winter snow cover and the mass of ice in the Greenland Ice Sheet and Arctic glaciers, and warming sea surface and permafrost temperatures.

Highlights

• The average surface air temperature for the year ending September 2017 is the 2nd warmest since 1900; however, cooler spring and summer temperatures contributed to a rebound in snow cover in the Eurasian Arctic, slower summer sea ice loss, and below-average melt extent for the Greenland ice sheet.
• The sea ice cover continues to be relatively young and thin with older, thicker ice comprising only 21% of the ice cover in 2017 compared to 45% in 1985.
• In August 2017, sea surface temperatures in the Barents and Chukchi seas were up to 4° C warmer than average, contributing to a delay in the autumn freeze-up in these regions.
• Pronounced increases in ocean primary productivity, at the base of the marine food web, were observed in the Barents and Eurasian Arctic seas from 2003 to 2017.
• Arctic tundra is experiencing increased greenness and record permafrost warming.
• Pervasive changes in the environment are influencing resource management protocols, including those established for fisheries and wildfires.
• The unprecedented rate and global reach of Arctic change disproportionally affect the people of northern communities, further pressing the need to prepare for and adapt to the new Arctic.

Video:

There are several sections of the report, for temperature, sea ice, etc. You can access each section here: http://ift.tt/2AvzObH

One graph in the sea ice section caught my eye:

Time series of ice extent anomalies in March (the month of maximum ice extent) and September (the month of minimum ice extent). The anomaly value for each year is the difference (in %) in ice extent relative to the mean values for the period 1981-2010. The black and red dashed lines are least squares linear regression lines. The slopes of these lines indicate ice losses of -2.7% and -13.2% per decade in March and September, respectively. Both trends are significant at the 99% confidence level.

The September rate of loss is about 4 times higher than the March rate of loss. This suggests to me that something I’ve long mentioned – albedo changes which primarily manifest themselves in the summer when there is more incoming solar radiation might be a big part of the issue. Carbon soot, specifically.

This is supported by something I covered at AGU14: satellites detect albedo change in the Arctic, resulting in more absorbed solar radiation

From that study:

Since the year 2000, the rate of absorbed solar radiation in the Arctic in June, July and August has increased by five percent, said Norman Loeb, of NASA’s Langley Research Center, Hampton, Virginia. The measurement is made by NASA’s Clouds and the Earth’s Radiant Energy System (CERES) instruments, which fly on multiple satellites.

The Arctic Ocean is absorbing more of the sun’s energy in recent years as white, reflective sea ice melts and darker ocean waters are exposed. The increased darker surface area during the Arctic summer is responsible for a 5 percent increase in absorbed solar radiation since 2000. Image Credit: NASA Goddard’s Scientific Visualization Studio/Lori Perkins

While a five percent increase may not seem like much, consider that the rate globally has remained essentially flat during that same time. No other region on Earth shows a trend of potential long-term change.