Iceberg, © Siegfried Matull

Record Low for Ice in the Arctic

With all the attention to wolves last week, here is something you may have missed.  Arctic sea ice has hit a new low, not just beating the old record, but beating it with an expected three weeks remaining in the melting season.

Arctic sea ice naturally goes through an annual cycle of expansion and contraction, with summer ice extent reaching its lowest point in September, then stabilizing and starting to expand again as the weather gets colder.  The previous record low of 1.61 million square miles occurred on September 18, 2007. The new low of 1.58 million square miles was set on August 26, 2012, with South-Carolina-sized areas of ice melting daily.  If this keeps up through mid-September, the minimum for 2012 will shatter all previous records.

The six lowest sea ice extents since satellite measurements began in 1979have all occurred in the past six years. While we don’t know for sure what the ice data looked like prior to that, the adventures of explorers searching for the fabled “Northwest Passage” remind us that heavy ice cover was once the norm.

This graph from the National Snow and Ice Data Center shows the dramatic loss of Arctic ice in 2012 so far.

 

What’s even more alarming about the new record is that this wasn’t even a spectacularly warm summer in the Arctic. Rather, it seems that year after year of big summer ice melts have made the sea ice thinner and more fragile, thus more prone to melting each year. Cambridge University professor Peter Wadhams estimates that the ice pack “has lost at least 40% of its thickness since the 1980s, and if you consider the shrinkage as well it means that the summer ice volume is now only 30% of what it was in the 1980s.”

If all this ice loss strikes you as bad news for polar bears and other Arctic wildlife, you’re right. If you think that’s the only thing we have to worry about, think again. The difference with and without sea ice is like the difference between wearing a white shirt and a black shirt on a hot, sunny day. The white ice reflects the sun’s energy back out toward space, but the dark surface water exposed when the ice melts absorbs much more of the sun’s energy, leading to even faster heating.

And all that dark, heat-absorbing water where once there was ice leads to another problem: the icy sediments at the bottom of the sea are starting to thaw as well.Professor Peter Wadhams points out, “we are also finding the open water causing seabed permafrost to melt, releasing large amounts of methane, a powerful greenhouse gas, to the atmosphere.”

This new low is another sign that climate change isn’t an issue we can just ignore and worry about later. It’s real, it’s urgent, and it’s affecting our planet right now.

 

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