Total Solar Irradiance

• Mechanisms that explain significant influences of solar variability on climate have yet to be identified
• Interesting associations have been found between these quantities
• For example, the Maunder Minimum (1645 - 1715) was associated with a Little Ice Age in Europe.
• Observed 11-year solar cycle variations in total solar irradiance are about 1.3 W/m2.

The image on the left shows the relationship between winter severity in Paris and London (top curve) and various measures of solar activity variations (bottom curves). Details of the solar activity since 1700 are indicated are shown by sunspot number data. The winter severity index has been shifted 40 years to the right to allow for cosmic-ray- produced carbon-14 to be assimilated into tree rings.