Solar Cycle Influence on Climate: Recent Evidence
Ka-Kit Tung [tung@amath.washington.edu], Dept. of Applied Mathematics, University of
Washington, Seattle
It has long been suspected that the variations in the Sun’s irradiance can affect the climate near
the Earth’s surface. Although evidence of solar influence in the upper atmosphere is strong, the
signal to noise ratio becomes small near the surface. Even so, the annual rate of warming from solar
min to solar max is comparable to that due to greenhouse gases. We can no longer claim that we are
studying the Sun’s influence on climate without confronting the problem near the Earth’s surface.
Recent observational and modeling evidence will be reviewed. Response to the known solar forcing
is a helpful measure of climate sensitivity, and can be used to calibrate model predictions of future
climate change to greenhouse radiative forcing.