Biotic feedback extends the life span of the biosphere

The Sun is becoming more luminous with time and will eventually overheat th e biosphere. However, life cools the Earth by amplifying the rate of silica te rock weathering and maintaining a low level of atmospheric CO2. Recent s tudies indicate a much stronger biotic weathering effect than in models use d to estimate the life span of the biosphere. Here we show that the resulti ng feedback lengthens the survival of complex life by delaying the loss of CO2 from the atmosphere. The weathering biota can potentially maintain the Earth in a habitable state when otherwise it would be too hat for them. If so, catastrophic warming rather than gradual CO2 starvation will terminate complex life. Despite the possibility of an irreversible collapse, the curr ent biosphere should remain resilient to carbon cycle perturbation or mass extinction events for at least 0.8 Gyr and may survive for up to 1.2 Gyr.