In what has become an alarmingly regular occurrence, the Arctic set another record for high temperatures in 2011. According to new data from the U.S. National Aeronautics and Space Administration (NASA), 2011 broke the previous record, set in 2010.
The region's temperature has been rising rapidly since the late 1970s.
Arctic amplification speeds up warming
Arctic air temperatures have risen at almost twice the rate of the global average rise over the past few decades. This arctic amplification of global warming is largely due to reduced surface reflectivity—and greater heat absorption—associated with the loss of snow and ice, especially sea ice.
As a result, most summer sea ice is projected to disappear by 2040, leaving only a small fringe of summer ice in Northeast Canada and Northern Greenland. Summer sea ice is important habitat for Arctic wildlife, and its decline opens previously inaccessible areas of the Arctic to shipping and industrial development.
“These changes have both local and global implications for people," says Clive Tesar, leader of the WWF Last Ice Area project. "Whether they are reindeer herder, hunters, or fishermen in the Arctic, or office workers in southern cities, people will ultimately feel these major changes to an integral part of the global weather system. We ignore these urgent signals at our peril. We need to both prepare for inevitable change, and work hard to reduce the severity of that change.”
Warming trend globally
Global temperature data released by NASA indicates that global surface temperatures in 2011 were the 9th highest on record, and that the warming was especially concentrated in the Arctic. "We know the planet is absorbing more energy than it is emitting," said James E. Hansen, director of NASA's Goddard Institute for Space Studies. "So we are continuing to see a trend toward higher temperatures. Even with the cooling effects of a strong La Niña influence and low solar activity for the past several years, 2011 was one of the 10 warmest years on record."
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Research carried out at the Catlin Arctic Survey’s Ice Base in March and April 2010 suggests that melting sea ice is weakening the Arctic Ocean’s ability to capture and store atmospheric carbon.
This study, carried out by a team at the Department of Fisheries and Oceans, Canada, focuses on the efficiency of an important biological ‘pump’ that captures atmospheric carbon near the sea surface and then draws it down and stores it on the sea floor.
Phytoplankton (plant plankton), near the sea surface, capture atmospheric carbon and store it as non-sinking microscopic particles. Although these particles do not themselves sink, their sticky nature means they can capture heavier organic debris and become sufficiently dense that they fall to the ocean floor as ‘marine snow’, effectively removing significant amounts of atmospheric CO2 to the deep ocean for thousands of years.
The findings also show that carbon-rich gel-like particles (so-called transparent exopolymer particles, or TEPs) are stored in the sea ice during winter and are released into the water column during early spring. TEPs are an important feature in the carbon cycle as they both capture carbon and give marine snow its stickiness, enabling it to attract organic debris and sink.
Future increases in surface freshwater from melting sea-ice will likely strengthen water layering and could change carbon draw-down in the Arctic Ocean. Coupled with the continuing retreat of sea ice, this has implications for the capacity of the Arctic Ocean to mitigate increasing atmospheric CO2 emissions via carbon capture.
The oceans represent the largest active carbon sink on Earth, absorbing more than a quarter of the CO2 that humans put into the air. According to a recent estimate, the Arctic is responsible for 5 to 14 percent of the world’s CO2 uptake, although it accounts for only 3 percent of its ocean surface area.
Dr. Oliver Wurl, who carried out this research, was part of an international team of scientists who lived and worked at the Catlin Ice Base on the Arctic Ocean during the brutally cold winter-spring transition as part of the Catlin Arctic Survey 2010 expedition.
"The data was really hard-won," said Dr. Wurl. "Collecting sea water samples in minus-40ºC is not something I would recommend to anyone, but to see this data forming part of an important jigsaw puzzle makes all the hardship worthwhile.”
The paper is published in the Journal of Geophysical Research.
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The Catlin Arctic Survey, sponsored by global specialty insurer and reinsurer Catlin Group Limited involves an ‘Ice Base’ and an ‘Explorer Team’.
The Ice Base is a unique, purpose-built field research station, located on floating sea ice in the Canadian Arctic archipelago (78°45’N, 103°30’W). This Winter/Spring Ice Base played host to an international team of research scientists from the UK, U.S. and Canada in both 2010 and 2011.
The Explorer Team, in 2010, comprised Charlie Paton, Martin Hartley and Ann Daniels. The team undertook a long-range survey, traveling across the Arctic’s sea ice, collecting water samples to provide data on ocean acidification. Explorer Teams also participated in the 2009 and 2011 Catlin Arctic Surveys.