Department of Physics and Astronomy
Stony Brook University
7:30 pm; via Zoom
Friday, October 02, 2020

The Sun in Time: Solar Irradiance and Climate Change

Prof. Frederick Walter

The temperature of the Earth is set by an equilibrium between the Solar energy absorbed and the heat radiated away by the Earth. For the past 4.4 billion years this precarious equilibrium has held even as the Solar irradiance has increased by about 30%. Today, as the Earth is noticeably growing warmer, some claim that an increase in Solar irradiance is to blame for global warming, while others point to a decrease in Solar magnetic activity as presaging a coming "Maunder minimum" and a global cooling.

I shall review the evidence that the temperature of the Earth has remained stable for the past 4.4 billion years. I shall discuss what we know of solar and stellar variability, and discuss how stable temperatures have been maintained even as the Sun has brighted. The evidence shows that none of the rapid change in global temperature over the past century can be attributed to the Sun. Furthermore, I shall argue that even a prolonged activity minimum is unlikely to start an episode of global cooling.

We have only ourselves to blame for bringing on climate change and global warming and all their associated ills.

Prof. Walter, a resident of East Setauket, studies star birth, stellar weather, and star death using the Chandra and XMM-Newton X-ray observatories, the Hubble Space Telescope, and telescopes in Arizona, Hawaii and Chile. He has been a professor of Astronomy at Stony Brook since 1989.