Not Spaghetti

Dr. Judith Curry is chair of the School of Earth and Atmospheric Sciences at Georgia Tech, and has an extensive background in studying Earth's climate, particularly regarding changes in storms, hurricanes, and the like under changing climate conditions. She recently coauthored what seems a very interesting paper on the growth of Antarctic sea ice - apparently the effect of a moderate degree of warming such as we've seen so far is to actually increase sea ice extent in the southern ocean, thanks to increased precipitation in the form of snow. Higher sea temperatures mean more evaporation of water (mostly closer to the equator) which in turn leads to higher levels of precipitation (mostly further south), and if it's cold enough to snow, then paradoxically the result is actually more ice on the water surface, not less.

Since various people thought some of my recent comments trying to explain certain basic properties of the greenhouse effect were educational, I thought I'd repost them here organized in more narrative fashion, as a follow-on to the previous "climate change basics" post. The questions this time regarded the definitions of radiative forcing and feedbacks, the magnitude of various feedbacks, and the relation of surface energy fluxes (the subject of the previous post) to different forcings. Once again the Trenberth-Fasullo-Kiehl diagram of Earth's energy flows is a useful reference:

The following is a collection and rearrangement of some of my comments on how we know about the radiative effects of greenhouse gases like carbon dioxide and how big they are, made on another blog. I'm posting these here as in working things out to my own satisfaction to try to respond to some rather egregiously wrong claims by the blogger there, I believe I clarified a few things in a way that's worth preserving.

The starting view here has to be the Kiehl-Trenberth diagram of Earth's energy flows, even though in some ways (which I'll get to below) it may be slightly misleading.