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| Titel |
Climate impacts on rising atmospheric CO2 from long-term time-series of CO2 and O2 |
| VerfasserIn |
R. F. Keeling, L. E. Rafelski, S. C. Piper |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250031075
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| Zusammenfassung |
| The long-term time series of atmospheric CO2 and O2 concentrations from the Scripps
Institution of oceanography now span 51 and 19 years, respectively. These time series will be
presented together with the ice-core CO2 records and discussed in terms of the processes
controlling the atmospheric CO2 rise, particularly the sensitivity of the natural sinks for CO2
in the land and ocean to climate changes.
The CO2 record provides constraints on the sensitivity of the land sinks to climate. The
CO2 rise can be expressed as an anomaly relative to the trend expected from fossil-fuel
burning, land use emissions, and uptake by the land biosphere and oceans, with the latter two
processes depicted by simple reservoir models (land sink driven by CO2 fertilization).
Despite uncertainties, the anomaly computed this way shows an evident link with global land
temperature, with both the anomaly and temperature trend showing breaks in slope
around 1940 and 1980. Climate effects on the land biosphere may thus explain two
otherwise puzzling features in the CO2 record: the plateau in growth in the 1940s
and the persistent high growth after 1980. The implied effect of warming on CO2
suggested by this decadal variability is too small to be a significant climate feedback,
however.
Additional constraints on the climate sensitivity of ocean sinks can be obtained by
combining the CO2 and O2 records. The ocean CO2 sink that would have been obtained in
the absence of climate change is quite well constrained based on ocean observations of
chlorofluorocarbons. This sink can be compared to the sink computed from the
global O2 budget, assuming the oceans have not been a long-term source or sink for
O2. The comparison reveals a significant discrepancy, which suggests that climate
changes are impacting some combination of the long-term O2 and CO2 fluxes. The
climate effect is qualitatively consistent with ocean models, which predict that
warming will reduce oceanic uptake of CO2 and induce oceanic outgassing of O2. |
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