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| Titel |
Can we trust empirical marine DMS parameterisations within projections of future climate? |
| VerfasserIn |
P. R. Halloran, T. G. Bell, I. J. Totterdell |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 7, no. 5 ; Nr. 7, no. 5 (2010-05-20), S.1645-1656 |
| Datensatznummer |
250004775
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| Publikation (Nr.) |
 copernicus.org/bg-7-1645-2010.pdf |
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| Zusammenfassung |
| Dimethylsulphide (DMS) is a globally important aerosol precurser. In 1987
Charlson and others proposed that an increase in DMS production by certain
phytoplankton species in response to a warming climate could stimulate
increased aerosol formation, increasing the lower-atmosphere's albedo, and
promoting cooling. Despite two decades of research, the global significance
of this negative climate feedback remains contentious. It is therefore
imperative that schemes are developed and tested, which allow for the
realistic incorporation of phytoplankton DMS production into Earth System
models. Using these models we can investigate the DMS-climate feedback and
reduce uncertainty surrounding projections of future climate. Here we examine
two empirical DMS parameterisations within the context of an Earth System
model and find them to perform marginally better than the standard DMS
climatology at predicting observations from an independent global dataset. We
then question whether parameterisations based on our present understanding of
DMS production by phytoplankton, and simple enough to incorporate into global
climate models, can be shown to enhance the future predictive capacity of
those models. This is an important question to ask now, as results from
increasingly complex Earth System models lead us into the 5th assessment of
climate science by the Intergovernmental Panel on Climate Change. Comparing
observed and predicted inter-annual variability, we suggest that future
climate projections may underestimate the magnitude of surface ocean DMS
change. Unfortunately this conclusion relies on a relatively small dataset,
in which observed inter-annual variability may be exaggerated by biases in
sample collection. We therefore encourage the observational community to make
repeat measurements of sea-surface DMS concentrations an important focus, and
highlight areas of apparent high inter-annual variability where sampling
might be carried out. Finally, we assess future projections from two
similarly valid empirical DMS schemes, and demonstrate contrasting results.
We therefore conclude that the use of empirical DMS parameterisations within
simulations of future climate should be undertaken only with careful
appreciation of the caveats discussed. |
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