Solar Irradiance Variations and Global Ocean Temperatures

Abstract

Long-term (decades to centuries) variations in the surface temperature of the earth may have been caused, at least in part, by variations in the sun's total irradiance (the solar “constant”). The observed similarity between the envelope of the 11-year solar-activity cycle and a time series of globally averaged sea-surface temperatures over the past 130 years lends some credibility to this possibility, and suggests that long-term variations in irradiance may accompany the long-term variations in solar activity. This connection has been explored with the aid of a one-dimensional model of the thermal response of the global ocean to variations in surface heating, and the inferred relationship has been extended backward in time to deduce a total irradiance at the time of the Maunder Minimum of solar activity about 1% less than the present value. The underlying cause for a connection between solar activity and luminosity on long time scales is unknown, and presents a major challenge for solar physics.