Climate and Carbon-cycle Modeling Group, Lawrence Livermore National Laboratory, Livermore, California, USA
"The Cycle of Greenhouse Gases"
Carbon dioxide is one of the most important greenhouse gases in the
atmosphere, and its atmospheric content is thought to bear a somewhat
complicated relationship with solar luminosity. On long time scales
(i.e., longer than several hundred thousand years), atmospheric CO2
content adjusts to largely compensate for changes in solar luminosity
such that the surface temperature of the Earth is relative stable.
However, on shorter time scales (i.e, thousands of years and less),
changes in atmospheric carbon dioxide content amplify the effect of
changes in solar luminosity on Earth's surface temperature. This
behavior occurs because longer time scale changes in atmospheric CO2
content are governed by the weathering of silicate minerals in soils,
whereas shorter time scale changes are largely governed by the
partitioning of carbon between the atmosphere and oceans. In this
presentation, I will review the global carbon cycle, and, using a
geochemical model, quantify the response of the carbon cycle to
changes in solar variability as a function of frequency and amplitude
of that variability.