Don Neidig

What Astronomers Might Want to Know About Global Warming

Abstract: The physics of the greenhouse effect is well understood and remains unchallenged as the warming mechanism which maintains Earth’s baseline global mean surface temperature. The question, now, about anthropogenic additions of greenhouse gases has drawn much scientific (and political) attention. Physics-based calculations of temperature response to anthropogenic additions are found to be broadly consistent with (1) observed post-industrial global surface temperature change as well as with temperature changes in the distant past, and (2) observed changes in the atmospheric temperature profile, to the exclusion of natural forcing mechanisms. This presentation reviews the climate system and its current energy imbalance, the fundamental physics of the greenhouse effect, climate sensitivity to greenhouse gas forcing, feedbacks, complexities introduced by the presence of a condensable greenhouse gas (water vapor), and global temperatures we might expect in the future.