Monday, September 21, 2009

Arctic sea ice extent seasonal minimum reach without setting a record and now expanding again

In a special report, the National Snow and Ice Data Center reported in its Arctic Sea Ice News dated September 17, 2009 entitled "Arctic sea ice reaches annual minimum extent" that the minimum extent of Arctic sea ice occurred on September 12, 2009 and the extent of Arctic sea ice is expanding again due to seasonal cooling. As the report says:

Arctic sea ice appears to have reached its minimum extent for the year, the third-lowest extent since the start of satellite measurements in 1979. While this year's minimum extent is above the record and near-record minimums of the last two years, it further reinforces the strong negative trend in summertime ice extent observed over the past thirty years.

Specifically,

On September 12, 2009 sea ice extent dropped to 5.10 million square kilometers (1.97 million square miles). This appears to have been the lowest point of the year, as sea ice has now begun its annual cycle of growth in response to autumn cooling. The 2009 minimum is the third-lowest recorded since 1979, 580,000 square kilometers (220,000 square miles) above 2008 and 970,000 square kilometers (370,000 square miles) above the record low in 2007.

The 2009 minimum is 1.61 million square kilometers (620,000 square miles) below the 1979 to 2000 average minimum and 1.28 million square kilometers (490,000 square miles) below the thirty-year 1979 to 2008 average minimum.

Sure, the latest data is on that 30-year downwards trend line, but given that the last two years have not been as cataclysmic as a lot of prognosticators were claiming back in 2007 and even at the start of 2008 (Arctic ice-free in 2008?), I would prefer to take a wait-and-see attitude towards the current trend.

In addition, there is some question as to whether the global economic recession of the past two years may have reduced carbon "emissions" enough to possibly influence current global climate conditions. Hard to say. I would simply note that reducing "emissions" would not directly reduce the existing carbon load in the atmosphere, and it is that existing load that impacts climate in the here and now. Maybe what it also says is that the prognosticators are being quite misleading when they suggest that their forecasts decades into the future can be depended upon. Sane people know that forecasts of anything tend to be quite unreliable, especially those concerning the future. Typically forecasts seem based on a presumption that "unless something changes", when in the real world everything is in a constant state of change.

-- Jack Krupansky

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