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The CO2 inhibition of terrestrial isoprene emission significantly affects future ozone projections

Young, P. J.; Arneth, Almut LU ; Schurgers, Guy LU ; Zeng, G. and Pyle, J. A. (2009) In Atmospheric Chemistry and Physics 9(8). p.2793-2803
Abstract
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... (More)
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 O-3 and OH levels. The impact on surface O-3 was significant. Including the CO2-inhibition of isoprene resulted in opposing responses in polluted (O-3 decreases of up to 10 ppbv) vs. less polluted (O-3 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 similar to 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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Atmospheric Chemistry and Physics
volume
9
issue
8
pages
2793 - 2803
publisher
Copernicus Gesellschaft Mbh
external identifiers
  • wos:000265743100012
  • scopus:70450244060
ISSN
1680-7324
project
Climate Initiative
language
English
LU publication?
yes
id
de33f831-6f11-4246-9cbd-92610f1c008d (old id 1428102)
date added to LUP
2009-06-25 13:14:52
date last changed
2017-07-09 03:44:52
@article{de33f831-6f11-4246-9cbd-92610f1c008d,
  abstract     = {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 O-3 and OH levels. The impact on surface O-3 was significant. Including the CO2-inhibition of isoprene resulted in opposing responses in polluted (O-3 decreases of up to 10 ppbv) vs. less polluted (O-3 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 similar to 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.},
  author       = {Young, P. J. and Arneth, Almut and Schurgers, Guy and Zeng, G. and Pyle, J. A.},
  issn         = {1680-7324},
  language     = {eng},
  number       = {8},
  pages        = {2793--2803},
  publisher    = {Copernicus Gesellschaft Mbh},
  series       = {Atmospheric Chemistry and Physics},
  title        = {The CO2 inhibition of terrestrial isoprene emission significantly affects future ozone projections},
  volume       = {9},
  year         = {2009},
}