 |
| Titel |
A model-based constraint on CO2 fertilisation |
| VerfasserIn |
P. B. Holden, N. R. Edwards, D. Gerten, S. Schaphoff |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 1 ; Nr. 10, no. 1 (2013-01-23), S.339-355 |
| Datensatznummer |
250017476
|
| Publikation (Nr.) |
 copernicus.org/bg-10-339-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
| We derive a constraint on the strength of CO2 fertilisation of the
terrestrial biosphere through a "top-down" approach, calibrating Earth
system model parameters constrained by the post-industrial increase of
atmospheric CO2 concentration. We derive a probabilistic prediction for
the globally averaged strength of CO2 fertilisation in nature, for the
period 1850 to 2000 AD, implicitly net of other limiting factors such as
nutrient availability. The approach yields an estimate that is independent
of CO2 enrichment experiments. To achieve this, an essential
requirement was the incorporation of a land use change (LUC) scheme into the
GENIE Earth system model. Using output from a 671-member ensemble of
transient GENIE simulations, we build an emulator of the change in
atmospheric CO2 concentration change since the preindustrial period. We
use this emulator to sample the 28-dimensional input parameter space. A
Bayesian calibration of the emulator output suggests that the increase in
gross primary productivity (GPP) in response to a doubling of CO2 from
preindustrial values is very likely (90% confidence) to exceed 20%,
with a most likely value of 40–60%. It is important to note that we do
not represent all of the possible contributing mechanisms to the terrestrial
sink. The missing processes are subsumed into our calibration of CO2
fertilisation, which therefore represents the combined effect of CO2
fertilisation and additional missing processes. If the missing processes are
a net sink then our estimate represents an upper bound. We derive calibrated
estimates of carbon fluxes that are consistent with existing estimates. The
present-day land–atmosphere flux (1990–2000) is estimated at −0.7 GTC yr−1 (likely, 66%
confidence, in the range 0.4 to −1.7 GTC yr−1). The present-day ocean–atmosphere flux (1990–2000) is
estimated to be −2.3 GTC yr−1 (likely in the range −1.8 to −2.7 GTC yr−1).
We estimate cumulative net land emissions over the
post-industrial period (land use change emissions net of the CO2
fertilisation and climate sinks) to be 66 GTC, likely to lie in the range 0
to 128 GTC. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|