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Habitable Zones & Global Climate: March 2018


Various climate states at high obliquity are realized for a range of stellar irradiance using a dynamical atmosphere-ocean-sea ice climate model in an aquaplanet configuration.

Dozens of habitable zone, approximately earth-sized exoplanets are known today.

The search for habitable exoplanets inspires the question - how do habitable planets form? Planet habitability models traditionally focus on abiotic processes and neglect a biotic response to changing conditions on an inhabited planet.

Traditional definitions of the habitable zone assume that habitable planets contain a carbonate-silicate cycle that regulates CO2 between the atmosphere, surface, and the interior.

Jupiter's radio emission has been linked to its planetary-scale magnetic field, and spacecraft investigations have revealed that most planets, and some moons, have or had a global magnetic field.

The stability of Earth's climate on geological timescales is enabled by the carbon-silicate cycle that acts as a negative feedback mechanism stabilizing surface temperatures via the intake and outgas of atmospheric carbon.

Our present-day atmosphere is often used as an analog for potentially habitable exoplanets, but Earth's atmosphere has changed dramatically throughout its 4.5 billion year history.

Because of the recent technological advances, the key technologies needed for precision space optical astrometry are now in hand.

The discovery of a truly habitable exoplanet would be one of the most important events in the history of science.

This is a white paper in response to the National Academy of Sciences "Exoplanet Science Strategy" call. We summarize recent advances in theoretical habitability studies and argue that such studies will remain important for guiding and interpreting observations.

Habitable planetary are commonly imagined to be temperate planets like Earth, with areas of open ocean and warm land. In contrast, planets with colder surfaces and permanent snowball states, where oceans are entirely ice-covered, are believed to be inhospitable.