At the onset of the the Holocene (ca. 12 ka BP), CO2 concentration was
about 265 ppm and reached a minimum of 260 by 7 ka BP. Thereafter,
CO2 concentration steadily increased by 20 ppm to the pre-industrial level
of 280 ppm. To date it is unclear what mechanisms drive atmospheric CO2
concentration trends dying interglacial periods. While the majority of
climate-carbon cycle model simulations agree that the ocean was the main
source of carbon entering the atmosphere, the impact of land carbon
changes on atmospheric CO2 concentration is less clear. To understand the
role of the land biosphere on atmospheric CO2 concentration changes
during the present interglacial, we use transient simulations with
the new climate-carbon cycle model CLIMBER-JSBACH. The natural
variability of vegetation cover, land carbon storage, and fire activity
are evaluated using the Holocene simulations under perturbed climate
forcings. It will be shown, that second-order processes, such as natural
fire activity, act on the same order of magnitude as the simulated
anomaly of in the total biomass carbon between the Holocene and
pre-industrial climate.
16.04.2013
15:15 h