A New Maunder Minimum?

Could we be heading into an Ice Age?

Astronomers recently found that our sun may be heading into a period of low activity where the 11 year cycle of sunspot maximums we have been experiencing over the last few centuries may take a pause. Papers suggest that the next sunspot cycle after the one we are just starting will be low or not occur at all.

The sun experienced a pause of this kind around 1645 — 1715 when sun spot activity died away to nothing. This was termed the Maunder Minimum and coincided with the Little Ice Age in Europe.

This would be great news if our sun was to enter a period of reduced activity as it might reduce human driven climate change and allow us more time to get our act together. Unfortunately, the reduced forcing would be of the order of 0.24W/m2 by 2100. This would be very little compared to the approx. 2 W/m2 we will have created by then. 

A recent study of the likely reduction in forcing from a cooler sun by Rahmstorf and Feulner assesses the likely impact of a Maunder Minimum of climate this century:

http://www.agu.org/pubs/crossref/2010/2010GL042710.shtml

They conclude that a new solar minimum of several decades (similar to the Maunder Minuimum) would result in a lowering of temperatures by around 0.3 C by 2100. This cannot be compared to the 4C to 6C we are expecting from human forcing.

Refer also to a great article from one of the authors on realclimate:- http://www.realclimate.org/index.php/archives/2011/06/what-if-the-sun-went-into-a-new-grand-minimum/

Just for the sceptics, they can’t have it both ways! If, as they claim, the climate sensitivity to forcing is much less than the IPCC estimates of around 3 degrees C per doubling of CO2, then a slight reduction in the suns radiation would be of even less impact than the 0.3C estimated above.

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