Saturday round-up: Melting ice speeds Arctic warming

The image shows satellite-derived Arctic surface temperature trends during autumn over the period 1981-2008. Greenland is on the right, North America at the bottom of the image, and Europe at the top. Warming has been enhanced over the Arctic Ocean due to the dramatic recent decline in sea ice cover. The brightest reds correspond to a 0.42°C rise over this period, while the blue-ish colours represent falling surface temperatures, up to a maximum of 0.10°C. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio.

The image shows satellite-derived Arctic surface temperature trends during autumn over the period 1981-2008. Greenland is on the right, North America at the bottom of the image, and Europe at the top. Warming has been enhanced over the Arctic Ocean due to the dramatic recent decline in sea ice cover. The brightest reds correspond to a 0.42°C rise over this period, while the blue-ish colours represent falling surface temperatures, up to a maximum of 0.10°C. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio.

Air temperatures near the Arctic surface have risen almost twice as much as the global average in recent decades – and melting sea ice is the main cause. This process will continue to accelerate, according to James Screen and Ian Simmonds of the University of Melbourne, who revealed their results in Thursday’s edition of Nature.

“The sea ice acts like a shiny lid on the Arctic Ocean,” Screen explains. “When it is heated, it reflects most of the incoming sunlight back into space. When the sea ice melts, more heat is absorbed by the water. The warmer water then heats the atmosphere above it. This feedback system has warmed the atmosphere at a faster rate than it would otherwise.” “It was previously thought that loss of sea ice could cause further warming,” adds Simmonds. “Now we have confirmation this is already happening.”

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