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| Titel |
The CO2 inhibition of terrestrial isoprene emission significantly affects future ozone projections |
| VerfasserIn |
P. J. Young, A. Arneth, G. Schurgers, G. Zeng, J. A. Pyle |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 8 ; Nr. 9, no. 8 (2009-04-27), S.2793-2803 |
| Datensatznummer |
250007213
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| Publikation (Nr.) |
 copernicus.org/acp-9-2793-2009.pdf |
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| Zusammenfassung |
| Simulations of future tropospheric composition often include substantial
increases in biogenic isoprene emissions arising from the Arrhenius-like
leaf emission response and warmer surface temperatures, and from enhanced
vegetation productivity in response to temperature and atmospheric CO2
concentration. However, a number of recent laboratory and field data have
suggested a direct inhibition of leaf isoprene production by increasing
atmospheric CO2 concentration, notwithstanding isoprene being produced
from precursor molecules that include some of the primary products of carbon
assimilation. The cellular mechanism that underlies the decoupling of leaf
photosynthesis and isoprene production still awaits a full explanation but
accounting for this observation in a dynamic vegetation model that contains
a semi-mechanistic treatment of isoprene emissions has been shown to change
future global isoprene emission estimates notably. Here we use these
estimates in conjunction with a chemistry-climate model to compare the
effects of isoprene simulations without and with a direct
CO2-inhibition on late 21st century O3 and OH levels. The
impact on surface O3 was significant. Including the CO2-inhibition
of isoprene resulted in opposing responses in polluted (O3 decreases of
up to 10 ppbv) vs. less polluted (O3 increases of up to 10 ppbv) source
regions, due to isoprene nitrate and peroxy acetyl nitrate (PAN) chemistry.
OH concentration increased with relatively lower future isoprene emissions,
decreasing methane lifetime by ~7 months (6.6%). Our simulations
underline the large uncertainties in future chemistry and climate studies
due to biogenic emission patterns and emphasize the problems of using
globally averaged climate metrics (such as global radiative forcing) to
quantify the atmospheric impact of reactive, heterogeneously distributed
substances. |
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