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Swansong Biospheres: The biosignatures of inhabited earth-like planets nearing the end of their habitable lifetimes

Published online by Cambridge University Press:  06 January 2014

Jack T. O'Malley-James
Affiliation:
School of Physics & Astronomy, University of St Andrews, St Andrews, UK email: jto5@st-andrews.ac.uk
Jane S. Greaves
Affiliation:
School of Physics & Astronomy, University of St Andrews, St Andrews, UK email: jto5@st-andrews.ac.uk
John A. Raven
Affiliation:
Division of Plant Sciences, University of Dundee at TJHI, The James Hutton Institute, Invergowrie, Dundee, UK email: j.a.raven@dundee.ac.uk
Charles S. Cockell
Affiliation:
UK Centre for Astrobiology, School of Physics & Astronomy, University of Edinburgh, Edinburgh, UK email: c.s.cockell@ed.ac.uk
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Abstract

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The biosignatures of life on Earth are not fixed, but change with time as environmental conditions change and life living within those environments adapts to the new conditions. A latitude-based climate model, incorporating orbital parameter variations, was used to simulate conditions on the far-future Earth as the Sun enters the late main sequence. Over time, conditions increasingly favour a unicellular microbial biosphere, which can persist for a maximum of 2.8 Gyr from present. The biosignature changes associated with the likely biosphere changes are evaluated using a biosphere-atmosphere gas exchange model and their detectability is discussed. As future Earth-like exoplanet discoveries could be habitable planets nearing the end of their habitable lifetimes, this helps inform the search for the signatures of life beyond Earth

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2013 

References

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