Scientists have said that global climate change will bring us severe and unusual weather. That would be a hard point to argue. Here are two recent, apparently somewhat contradictory or perhaps merely odd, news stories about the sea and the global climate. The ice on the Arctic Sea has melted to record low levels while it has reached record highs in the Antarctic.
As Dr. Jeff Masters puts it – “Earth’s attic is on fire.”
The extraordinary decline in Arctic sea ice during 2012 is finally over. Sea ice extent bottomed out on September 16, announced scientists at the National Snow and Ice Data Center (NSIDC) on Wednesday. The sea ice extent fell to 3.41 million square kilometers, breaking the previous all-time low set in 2007 by 18%–despite the fact that this year’s weather was cloudier and cooler than in 2007. Nearly half (49%) of the icecap was gone during this year’s 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.
If the earth’s attic is on fire, the earth’s basement is freezing over. Sea ice in the Antarctic is growing and has reached record levels this year. Is this an indication that climate change is not as dramatic as previously thought? Unfortunately, scientists studying global warming predicted the growth in Antarctic ice several years ago and are predicting that it could suddenly reverse.
The data show that Antarctic sea ice growth in the 20th century might be mostly dictated by natural processes, Liu noted.
But that won’t be the case for the 21st century, since human-caused global warming is predicted to dominate the Antarctic climate and trigger faster melting of sea ice, he said. (See a map of global warming impacts worldwide.)
As increasing greenhouse gases continue to warm the oceans off Antarctica, more Antarctic precipitation will turn to rain, which rapidly melts snow and ice, according to the study, published this week in the journal Proceedings of the National Academy of Sciences.
The more the ice melts, the more the sun’s rays are absorbed into the dark ocean instead of being reflected back into the atmosphere, according to the study. This will further warm the ocean and melt even more sea ice.
The scientists predict the transition from natural variability to greenhouse-gas warming will begin soon: “I cannot give you a precise year—but definitely in this century,” Liu said.
Thanks to Phil Leon for contributing to the post.