A new three-dimensional global coupled carbon-climate model is
presented in the framework of the Community Climate System Model (CSM-1.4). A
1000-year control simulation has stable global annual mean surface temperature
and atmospheric CO2 with no flux adjustment in either physics or
biogeochemistry. At low frequencies (timescale > 20 years), the ocean tends
to damp (20-25%) slow, natural variations in atmospheric CO2
generated by the terrestrial biosphere. Transient experiments
(1820-2100) show that carbon sink strengths are inversely related to the rate
of fossil fuel emissions, so that carbon storage capacities of the land and
oceans decrease and climate warming accelerates with faster CO2
emissions. There is a positive feedback between the carbon and climate systems,
so that climate warming acts to increase the airborne fraction of anthropogenic
CO2 and amplify the climate change itself. Globally, the
amplification is small at the end of the 21st century in our model because of
its low transient climate response and the near-cancellation between large
regional changes in the hydrologic and ecosystem responses.
Author: S.C. Doney. K. Lindsay, I. Fung, and J. John (sdoney at whoi dot edu)
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