Runaway greenhouses and runaway glaciations: How stable is Earth’s climate?

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

Introduction Is Earth’s climate stable? At some level the answer is almost certainly “yes.” The evidence for this is two-fold. First, the geologic record indicates that liquid water has been present on Earth’s surface more or less continuously since about 4 Ga. (“Ga” stands for “giga-aeon,” which means “billions of years ago.”) We say “more or less” because, as discussed below, there appear to have been brief periods in Earth’s history when the planet was almost entirely frozen. And, second, life appears to have been present since at least 3.5 Ga (Schopf, 1993) and perhaps 3.9 Ga, if carbon isotopes are admitted as indirect evidence (Mojzsis et al., 1996). This latter requirement overlaps the first one to some extent because all organisms require liquid water during at least part of their life cycle. It is more stringent, however, in that liquid water can exist right up to the critical point (374 °C, 220 bar for pure water), whereas the upper temperature limit for life is ∼ 113 °C. (A common misconception is that liquid water requires temperatures below 100 °C, but this is only the boiling point at one atmosphere pressure. The ocean contains the equivalent of ∼ 270 bar of water vapor and so, like water in a pressure cooker, it would not boil until the temperature exceeded the critical temperature.) Another way of evaluating Earth’s climate stability is to compare Earth to its neighboring planets, Venus and Mars.

Original languageEnglish (US)
Title of host publicationFrontiers of Climate Modeling
PublisherCambridge University Press
Pages349-366
Number of pages18
Volume9780521791328
ISBN (Electronic)9780511535857
ISBN (Print)9780521791328
DOIs
StatePublished - Jan 1 2006

All Science Journal Classification (ASJC) codes

  • Earth and Planetary Sciences(all)

Fingerprint Dive into the research topics of 'Runaway greenhouses and runaway glaciations: How stable is Earth’s climate?'. Together they form a unique fingerprint.

  • Cite this

    Kasting, J. F. (2006). Runaway greenhouses and runaway glaciations: How stable is Earth’s climate? In Frontiers of Climate Modeling (Vol. 9780521791328, pp. 349-366). Cambridge University Press. https://doi.org/10.1017/CBO9780511535857.014