Abstract:  It is an interesting question how Earth was able to maintain habitable temperatures over 3 or 4 billion years, long enough for us to evolve. Several factors (including most famously the Faint Young Sun Paradox) argue for the difficulty of staying habitable, but nevertheless Earth evidently managed it. I will describe a simple-as-possible model designed to investigate this question, as well as a scheme for randomly generating planetary climate feedbacks systems. 100,000 diverse planets were produced using this scheme and each run 100 times (while exposed to randomly-occurring, climate-altering events) up until they became too hot or too cold or else had stayed habitable for 3 billion years. The results of the simulation suggest strongly that chance played a major role in determining whether planets stayed habitable, with possession of stabilizing feedbacks also found to be important. Observer selection explains why we find ourselves on a lucky planet like Earth.

Host:  Jim Kasting

Please click the link to join the webinar: https://psu.zoom.us/j/96060188956