Saturday, November 02, 2013

The good news is that Global Warming may be off the menu.

The bad news is that we may be looking at another Little Ice Age.

Lockwood thinks there is now a 25 per cent chance of a repetition of the last grand minimum, the late 17th century Maunder Minimum, when there were no sunspots for 70 years. Two years ago, Lockwood put the chances of this happening at less than 10 per cent (Journal of Geophysical Research, DOI: 10.1029/2011JD017013).

Little ice age

The Maunder Minimum coincided with the worst European winters of the little ice age, a period lasting centuries when several regions around the globe experienced unusual cooling. Tree ring studies suggest it cooled the northern hemisphere by up to 0.4 °C.

But Lockwood says we should not expect a new grand minimum to bring on a new little ice age. Human-induced global warming, he says, is already a more important force in global temperatures than even major solar cycles. Temperatures have risen by 0.85 °C since 1880, with more expected, according to the most recent assessment of the Intergovernmental Panel on Climate Change.

There may still be noticeable consequences. For instance, long term cold winters in the UK are common when solar activity is low. And less solar activity can slow the jet stream, triggering a suite of interlinked extreme weather events like the Russian heatwave of 2010, and the devastating floods in Pakistan that same year.


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