Research provides new hope for Earth-like climates on ‘Super-Earths’

Research provides new hope for Earth-like climates on ‘Super-Earths’

New research increases the odds that super-Earths could support human life.

Conventional wisdom holds that “super-Earths” are likely to be water worlds and unlikely to be able to support human life. New research by Nicolas B Cowan astrophysicist with Northwestern University’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)  and University of Chicago geophysicist Dorian Abbot contradicts that thinking.

Their findings, which will be published in the Astrophysical Journal on January 20, conclude that tectonically active super-Earths will store most of their water in the mantle store most of their water in the mantle and will have both oceans and exposed continents, enabling a stable climate such as Earth’s. They believe this is true regardless of the planet’s mass.

On Earth, water moves constantly back and forth between the rocky mantle and the oceans. This movement is controlled by plate tectonics and seafloor pressure, which is caused by gravity. It has been suggested that on a planet where the forces of gravity are 2 to 3 times that of Earth that more water would be forced to the surface, causing ocean levels which do not allow for continents.

“Super-Earths are expected to have deep oceans that will overflow their basins and inundate the entire surface, but we show this logic to be flawed,” Cowan said. “Terrestrial planets have significant amounts of water in their interior. Super-Earths are likely to have shallow oceans to go along with their shallow ocean basins.”

The existence of exposed continents is important for a planets climate. On planets with continents the carbon cycle is mediated by ground temperatures, which provides for a more stable climate.

“Such a feedback probably can’t exist in a waterworld, which means they should have a much smaller habitable zone,” Abbot said. “By making super-Earths 80 times more likely to have exposed continents, we’ve dramatically improved their odds of having an Earth-like climate.”

Cowan and Abbot still conclude that the chances of an Earth-like climate are dependent on the planet having active plate tectonics and on the amount of water present on the planet but their research holds out hope that at least some of the “super-Earths” found will have climates which are conducive to human life. Of course there are still questions about how much gravity humans can handle, even if we could get to one of these planets.

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