The temperature change associated with any reduction in sunspot activity
would likely be minimal and may not be enough to offset the impact of
greenhouse gases on global warming, according to scientists who have
published recent papers on the topic.
"Recent solar 11-year cycles are associated empirically with changes in
global surface temperature of 0.1 Celsius," said Judith Lean, a solar
physicist with the US Naval Research Laboratory.
If the cycle were to stop or slow down, the small fluctuation in
temperature would do the same, eliminating the slightly cooler effect of
a solar minimum compared to the warmer solar maximum. The phenomenon was
witnessed during the descending phase of the last solar cycle.
This "cancelled part of the greenhouse gas warming of the period
2000-2008, causing the net global surface temperature to remain
approximately flat -- and leading to the big debate of why the Earth
hadn't (been) warming in the past decade," Lean, who was not involved in
the three studies presented, said in an email to AFP.
A study in the March 2010 issue of Geophysical Research Letters explored
what effect an extended solar minimum might have, and found no more than
a 0.3 Celsius dip by 2100 compared to normal solar fluctuations.

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