Friday, April 24, 2009

Dim Sun won't cool Earth

'Quiet Sun' baffling astronomers
The Sun is the dimmest 
it has been for nearly a century

BBC: There are no sunspots, very few solar flares -- and our nearest star is the quietest it has been for a very long time...

In the mid-17th Century, a quiet spell -- known as the Maunder Minimum -- lasted 70 years, and led to a 'mini ice age.' This has resulted in some people suggesting that a similar cooling might offset the impact of climate change. According to Prof Mike Lockwood of Southampton University, this view is too simplistic. 'I wish the Sun was coming to our aid but, unfortunately, the data shows that is not the case.'

Prof Lockwood was one of the first researchers to show that the Sun's activity has been gradually decreasing since 1985, yet overall global temperatures have continued to rise... 'If the Sun's dimming were to have a cooling effect, we'd have see it by now.'...

Evidence from tree trunks and ice cores suggest that the Sun is calming down after an unusually high point in its activity. Professor Lockwood believes that as well as the Sun's 11-year cycle, there is an underlying solar oscillation lasting hundreds of years. He suggests that 1985 marked the 'grand maximum' in this long-term cycle and the Maunder Minimum marked its low point.

'We are re-entering the middle ground after a period which has seen the Sun in its top 10% of activity. 'We would expect it to be more than 100 years before we get down to the levels of the Maunder Minimum.'

He added that the current slight dimming of the Sun was not going to reverse the rise in global temperatures caused by the burning of fossil fuels. 'What we are seeing is consistent with a global temperature rise, not that the Sun is coming to our aid.'
Image source here.