During high school when the day promised heat I used to spend a minute in the morning to put sunglasses on my car. They were ‘shutter shades’, louvered sunglasses printed in bold lines on folded white cardboard meant to be spread just under the windshield. The car may not have contained power anything, a reliably functional speedometer, four working doors, or air conditioning apart from crank-open windows, but it did have science. The expanse of white cardboard reflected sunlight away from the car, keeping the interior cool(er); the white sun shield had a high albedo or reflectiveness. In contrast the interior’s dark upholstery absorbed heat from sunlight because of its low albedo.
Pale surfaces like snow cover reflect about 90% of solar rays. Uncovered ground? Only about 10%. That makes a big difference in the Arctic, the land of the midnight sun. There, snow cover extent is decreasing.
The state of change in the Arctic
June snow cover extent in North America was the third lowest on record. Arctic snow cover during the spring of 2014 was below average (below the long term mean of 1981-2010). Below average snow accumulation and above normal spring temperatures meant snow disappeared three to four weeks earlier than normal in western Alaska, western Russia, Scandinavia, and the Canadian subarctic. These findings are reported in the Arctic Report Card supported by the National Oceanic and Atmospheric Administration.
Craig McLean, assistant administrator for the NOAA Office of Oceanic and Atmospheric Research and Martin Jeffries, Arctic science advisor and program officer for Arctic and Global Prediction, Office of Naval Research, presented this year’s Arctic Report Card at the annual American Geophysical Union Fall Meeting in San Francisco, #AGU14.
The Arctic Report Card is an annual update provided since 2006 that summarizes changing conditions in the Arctic. It is a peer-reviewed report with contributors from 13 countries. “The Arctic Report Card 2014 presents observations vital for documenting the state of the Arctic environmental system, understanding the complex interactions and feedbacks within the system, and predicting its future,” said Martin Jeffries, principal editor of the 2014 Arctic Report Card.
Martin Jeffries announced that the Arctic continues a persistent warming trend that began over 30 years ago. Arctic air temperatures are warming at twice the rate of any other region of the world, a phenomenon called Arctic amplification. Amplified Arctic warming is contributing to more frequent and more extreme weather events in North America and Europe.
Darker surfaces
The Arctic is losing its white surfaces: snow and sea ice extent are decreasing overall. That’s not to say that the Arctic will soon be ice-free; winter sea ice is a returning force despite ice pack reductions in age and thickness. It’s the lessening extent and thickness of summer sea ice that makes the most immense impact. The summertime Arctic is turned toward the sun. That’s a lot of heat exposure applied to the open ocean, which has an extremely low albedo (reflectiveness) compared to sea ice.
Summer sea surface temperature is increasing in all Arctic Ocean seas. In the Chukchi Sea northwest of Alaska sea surface temperature is increasing 0.9°F [0.5°C] per decade.
Exposed ground and ocean waters absorb heat, increasing how much incoming solar radiation is retained, altering Earth’s energy budget and pushing it further out of balance. Absorbed solar energy in the Arctic is heightened due to lowered albedo. August 2014 measurements set a new record low for Greenland ice sheet albedo since satellite observations began in 2000; ice sheet melting contributes to sea level rise.
Low albedo levels in the Arctic cause surface temperatures to rise and the amount of heat the surface radiates to increase. Yet greenhouse gas concentrations in the atmosphere inhibit the amount of thermal energy which can escape into space. That means the amount of absorbed solar energy exceeds the amount of energy that can escape back to space. We’re out of balance.
“A one-degree global change is significant because it takes a vast amount of heat to warm all the oceans, atmosphere, and land by that much. In the past, a one- to two-degree drop was all it took to plunge the Earth into the Little Ice Age. A five-degree drop was enough to bury a large part of North America under a towering mass of ice 20,000 years ago.” ~ NASA Goddard Institute for Space Studies
Monitoring change
“Arctic warming is setting off changes that affect people and the environment in this fragile region, and has broader effects beyond the Arctic on global security, trade, and climate,” explained Craig McLean at the Arctic Report Card session.
Now is a time of change. Warming sea surface temperatures and changing sea ice conditions alter the timing of phytoplankton blooms, likely impacting marine food webs. Lessened sea ice summons interest in trade routes and oil. Plant growth trends change and some species’ ranges shift north.
At another American Geophysical Union Fall Meeting session, David Atkinson of the University of Victoria presented his work in Alaskan and Canadian coastal communities. He stated that “Northerners are excellent observers of their environment;” however, with the pace of modern changes “The old ways of knowing aren’t working so well.” Atkinson’s project cooperates and consults with Northern residents to enable the use of forecasting services, weather data and charts provided by agencies like NOAA’s National Weather Service or Environment Canada. They also arrange and install equipment to take more local measurements which residents are interested in monitoring.
“There is nothing about climate change or climate variability that says that the weather will become less variable,” said Rick Thoman, Climate Sciences and Services Manager, National Weather Service. “There’s increasing evidence that places at mid-latitudes … for instance Northeast United States, may experience more frequent snow storms and colder weather.” Climate is regulated by complex interactions among different components of the Earth system; ocean conditions, land components, and atmospheric trends all matter to climate and weather. For instance, cold air that once tended to remain over the Arctic can get displaced south by atmospheric conditions. Changing Arctic trends can impact conditions for the Northern Hemisphere, and they’re not always kind.
Reporting anomalies and normals
Monitoring and reporting the changing Arctic becomes more complex because of the swift rate of change. The average sea ice extent illustrated by a magenta line in the graphic above is calculated from measurements taken during the period 1981-2010. That 30-year window is the basis called a ‘long-term average’. John Walsh, International Arctic Research Center, University of Alaska Fairbanks, explains further in an essay included on the Arctic Report Card 2014 website titled ‘Depicting Arctic Change: Dependence on the Reference Period.’
“The 30-year “normals” are typically updated at the start of a new decade by operational agencies such as NOAA. For example, the present “normals” are for the 1981-2010 period, which replaced the 1971-2000 reference period after 2010. Even though such an updating of normals retains 66% of the years in the preceding 30-year period, the updates often result in non-negligible changes of the reference-period means.” ~ John Walsh
So if the magenta line had been drawn using the 1971-2000 reference period, this year’s September ice extent would look even more pathetic in comparison. That’s an interesting dilemma.
Martin Jeffries: “Observing, understanding and predicting are essential elements of the Arctic Research Plan of the Inter-agency Arctic Research Policy Committee and the implementation of the U.S. National Strategy for the Arctic Region.” We can expect continued and widespread change; maintaining and strengthening a robust observation network in the Arctic will provide data used to predict and prepare for future change.
Laura Nielsen
Frontier Scientists: presenting scientific discovery in the Arctic and beyond
Climate Change Watch project
