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| Titel |
The effects of vegetation parameter uncertainty on the magnitude of future terrestrial carbon sinks |
| VerfasserIn |
Zavareh Kothavala, Damon Matthews |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043009
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| Zusammenfassung |
| In this study, we examine the role of the terrestrial carbon cycle
in a changing climate at the centennial scale using an intermediate
complexity Earth system climate model which includes the effects
of dynamic vegetation and the global carbon cycle. We present a
series of ensemble simulations to evaluate the sensitivity of
simulated terrestrial carbon sinks to three key model parameters:
(a) the temperature dependence of soil carbon decomposition, (b)
the upper temperature limits on the rate of photosynthesis, and (c)
the nitrogen limitation of the maximum rate of carboxylation of
Rubisco. We integrated the model in fully coupled mode for a
1200-year spin-up period, followed by a 300-year transient simulation
starting at year 1800. Ensemble simulations were conducted varying
each parameter individually and in combination with other variables.
The results of the transient simulations show that terrestrial
carbon uptake is very sensitive to the choice of model parameters.
Changes in net primary productivity were most sensitive to the upper
temperature limit on the rate of photosynthesis, which also had a
dominant effect on overall land carbon trends; this is consistent
with previous research which has shown the importance of climatic
suppression of photosynthesis as a driver of carbon-climate feedbacks.
Soil carbon generally decreased with increasing temperature, though
the magnitude of this trend depends on both the net primary productivity
changes and the temperature dependence of soil carbon decomposition.
Vegetation carbon increased in some simulations, but this was not
consistent across all configurations of model parameters. Comparing
to global carbon budget observations, we indentify the subset of
model parameters which are consistent with observed carbon sinks;
this serves to narrow considerably the future model projections of
terrestrial carbon sink changes in comparison with the full model
ensemble. |
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