 |
| Titel |
Impact of atmospheric CO2 rise on chemical weathering of the continental surfaces |
| VerfasserIn |
Y. Godderis, C. Roelandt, E. Beaulieu, J. O. Kaplan, J. Schott |
| Konferenz |
EGU General Assembly 2009
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250030282
|
|
|
|
|
|
| Zusammenfassung |
| Continental weathering consumes atmospheric CO2. Recent analysis of field data
has shown that this flux is rapidly reacting to ongoing climate (ref 1) and land use
changes (ref 2), displaying an increase of up to 40 % over a few decades. Weathering
processes are thus a potentially important component of the present day global carbon
cycle.
We developed numerical model describing continental weathering reactions based on
laboratory kinetic laws and coupled to numerical model of the productivity of the biosphere
(B-WITCH)(ref 3,4). This model is able to simulate the chemical composition of streams for
both small and large continental watersheds. In this model, we emphasized the role of land
plants in controlling belowground hydrological fluxes and decreasing the pH of
percolating water through root respiration, both of which heavily impact weathering
rates.
Both climate change and increasing atmospheric CO2 concentrations affect the productivity
and biogeography of the terrestrial biosphere through direct climate effects and CO2
fertilization. With our weathering model coupled to a dynamic global vegetation model,
we have the capability to explore the impact of CO2 and climate change on rock
weathering.
With regards to CO2 fertilization, we calculate that the overall weathering rate may
potentially rise by 20 % when CO2 increases up to 8 times the present day pressure for a large
tropical watershed (Orinoco). This change is driven by a decrease in evapotranspiration
when CO2 rises, and thus by an increase in the weathering profile drainage. We
extend our sensitivity tests to the fertilization effect to 20 sites all over the world
under various climatic, biospheric and lithologic conditions, and the results will be
discussed.
ref 1: Gislason et al., EPSL, 277, 213-222, 2008
ref 2: Raymond et al.,Nature, 451, 449-452, 2008
ref 3: Godd |
|
|
|
|
|
|