Long Term Geochemical Carbon Cycle and Radiative Forcing

by Tommy on 5/04/2017

This is certainly worth reading, just for the weathering stuff.

http://www.nature.com/articles/ncomms14845

Future climate forcing potentially without precedent in the last 420 million years, Gavin L. Foster, Dana L. Royer and Daniel J. Lunt, Nature Communications 8, 14845 (4 April 2017), doi:10.1038/ncomms14845

The evolution of Earth’s climate on geological timescales is largely driven by variations in the magnitude of total solar irradiance (TSI) and changes in the greenhouse gas content of the atmosphere. Here we show that the slow ∼ 50 Wm−2 increase in TSI over the last ∼ 420 million years (an increase of ∼9 Wm−2 of radiative forcing) was almost completely negated by a long-term decline in atmospheric CO2. This was likely due to the silicate weathering-negative feedback and the expansion of land plants that together ensured Earth’s long-term habitability. Humanity’s fossil-fuel use, if unabated, risks taking us, by the middle of the twenty-first century, to values of CO2 not seen since the early Eocene (50 million years ago). If CO2 continues to rise further into the twenty-third century, then the associated large increase in radiative forcing, and how the Earth system would respond, would likely be without geological precedent in the last half a billion years.

It’s official. Again. We’re screwed.

Happy 420 Day! Last Call.

lifeform@charter.net

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