Extrasolar planets could have hospitable climates

A modeling study in the International Journal of Astrobiology suggests that some planets with high obliquity—those whose axes are tilted more strongly than Earth’s—have more potential for life-supporting climates than previously thought. Darren Williams (Penn State Erie, the Behrend College) and David Pollard (EMS Environment Institute, Pennsylvania State University) simulated the climates for 12 planetary scenarios that varied in their obliquity, level of atmospheric carbon dioxide, and configuration of continents. Using the GENESIS global circulation model, Williams and Pollard found that, as obliquity goes up for an Earthlike planet, high latitudes tend to warm while the tropics typically cool, with a slight global warming overall. They note that obliquity’s effect on climate occurs only for certain arrangements of continents, where seasonal extremes are magnified. The GENESIS simulations for other types of planets showed the greatest temperature extremes—with monthly surface temperatures averaging as high as 80 to 100°C (176 to 212°F)—occurred where high-latitude continents were most prevalent. However, Williams and Pollard found that none of the seasonal extremes in their high-obliquity scenarios were enough to generate a climate catastrophe in the form of a runaway greenhouse effect or global ice sheets. “Therefore, most Earth-like planets should be hospitable to life at high obliquity,” say the authors. Williams hopes to see the work used in modeling visible and infrared light curves of extrasolar planets for such efforts as the Space Interferometry Mission and the Terrestrial Planet Finder.



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President’s Corner - Leaders: Born or made?
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UCAR Community Calendar