Eugene S. Takle
© 2003
A significant fraction of the variation in Northern Hemisphere climate since the last ice age correlates with solar activity, according to recent evidence from ocean and ice cores (Bond et al., 2001). Precise global brightness changes on the sun have been monitored since 1978, and these show that changes in total solar irradiance (S) over this period has been less than 0.01%. However stars of the size of our sun undergo slow variations that may not be detectable with the relatively short period of precise observations now available (Foukal, 2003). In fact observation of other stars do show periods of higher activity as well as quiet periods similar to observations of our sun over the past 25 years. It also is possible that solar impact on climate may be driven by indirect forcing such as variable solar outputs of UV radiation or plasmas and magnetic fields than rely on more complex mechanisms to lead to warming of the EarthÕs troposphere. New instruments now being deployed should provide more evidence of the role of slow variations in solar output in causing changes in EarthÕs climate. Foukal (2003) provides an overview of current research in this area.
Reference
Bond, G., et al., 2001: Persistent solar influence on North Atlantic
climate during the Holocene. Science 294, 21-30.
Foukal, P., 2003: Can slow variations in solar luminosity provide missing
link between the sun and climate? EOS, 84, 205