James Kasting Online

In 1964 there was Stephen Dole’s “Habitable Planets For Man” which was the first informed guesstimate of habitable planets in the Galaxy. Dole’s planets had optically thin atmospheres and no modeling of their climate’s temporal evolution. The HabZone was from about 0.75 AU to 1.25 AU.

In 1978 Michael Hart presented the first evolution models of habitable planet atmospheres and discovered they were incredibly unstable – a very narrow band around the star allowed a long term stable atmosphere – but even Earth’s was due to become uninhabitable within a 100 million years. The HabZone had narrowed to just 0.95-1.01 AU – any further out and Earth became locked in ice; any closer in and the Earth became a greenhouse.

Then in 1993 James Kasting and his posse shook things up by accounting for climate stabilisation via carbonate weathering – and the habitable zone widened to 0.95 AU – 1.4 AU, perhaps even further. The year before Kasting & Ken Caldeira had extended the use-by for Earth’s biosphere to c. 1 billion AD. The odds for life in the Galaxy went up, and the mystery of the Fermi Paradox became an even bigger mystery.

Much to my surprise and joy most of James Kasting’s classic papers are available online…

James Kasting’s papers

…spanning his early 1980s papers to the present. Thank you James!

Notable papers are “The Lifespan of the Biosphere Revisited” (1992) and “Habitable Zones Around Main-Sequence Stars” (1993), but lots of other meaty stuff for planetology nerds like myself.