Wunderground.com - 1/11/13, Dr. Jeff Masters
It was another year of incredible weather extremes globally during 2012. The year featured two of the most expensive weather disasters in world history--Hurricane Sandy and the Great U.S. Drought of 2012, which will both cost more than $50 billion. Thankfully, no disasters had a death toll in excess of 2,000, though the 1,901 people dead or missing due to Super Typhoon Bopha in the Philippines may rank as that nation's 2nd deadliest typhoon ever.
Twenty-six weather disasters costing at least $1 billion occurred globally, according to insurance broker AON Benfield. Eleven billion-dollar weather disasters hit the U.S., a figure exceeded only by the fourteen such disasters in 2011. Nine billion-dollar weather disasters hit China, their highest total in a decade of record-keeping. I present for you, now, the top ten global weather stories of 2012, chosen for their meteorological significance and human and economic impact:
1) New Record Minimum for Arctic Sea Ice (September 16)
Sea ice extent in the Arctic fell to 3.41 million square kilometers on September 16, breaking the previous all-time low set in 2007 by 18%--despite the fact that 2012's Arctic weather was much cloudier and cooler than in 2007. Nearly half (49%) of the icecap was gone during 2012s minimum, compared to the average minimum for the years 1979 - 2000. This is an area approximately 43% of the size of the contiguous United States. And, for the fifth consecutive year--and fifth time in recorded history--ice-free navigation was possible in the Arctic along the coast of Canada (the Northwest Passage), and along the coast of Russia (the Northeast Passage or Northern Sea Route.) "We are now in uncharted territory," said NSIDC Director Mark Serreze.
"While we've long known that as the planet warms up, changes would be seen first and be most pronounced in the Arctic, few of us were prepared for how rapidly the changes would actually occur. While lots of people talk about opening of the Northwest Passage through the Canadian Arctic islands and the Northern Sea Route along the Russian coast, twenty years from now from now in August you might be able to take a ship right across the Arctic Ocean." Arctic sea ice is an important component of the global climate system. The polar ice caps help to regulate global temperature by reflecting sunlight back into space.
White snow and ice at the poles reflects sunlight, but dark ocean absorbs it. Replacing bright sea ice with dark ocean is a recipe for more and faster global warming. The fall air temperature over the Arctic has increased by 4 - 6°F in the past decade, and we could already be seeing the impacts of this warming in the mid-latitudes, by an increase in extreme weather events. Another non-trivial impact of the absence of sea ice is that is causes increased melting in Greenland, contributing to sea level rise.
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