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| Titel |
Projections of mid-century summer air-quality for North America: effects of changes in climate and precursor emissions |
| VerfasserIn |
J. Kelly, P. A. Makar, D. A. Plummer |
| 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 ; 12, no. 12 ; Nr. 12, no. 12 (2012-06-22), S.5367-5390 |
| Datensatznummer |
250011274
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| Publikation (Nr.) |
 copernicus.org/acp-12-5367-2012.pdf |
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| Zusammenfassung |
Ten year simulations of North American current and future air-quality were
carried out using a regional air-quality model driven by a regional climate
model, in turn driven by a general circulation model. Three separate summer
scenarios were performed: a scenario representing the years 1997 to 2006,
and two SRES A2 climate scenarios for the years 2041 to 2050. The first
future climate scenario makes use of 2002 anthropogenic precursor emissions,
and the second applied emissions scaling factors derived from the IPCC
Representative Concentration Pathway 6 (RCP 6) scenario to estimate
emissions for 2050 from existing 2020 projections. Ten-year averages of
ozone and PM2.5 at North American monitoring network stations were used
to evaluate the model's current chemical climatology. The model was found to
have a similar performance for ozone as when driven by an operational
weather forecast model. The PM2.5 predictions had larger negative
biases, likely resulting from the absence of rainwater evaporation, and from
sub-regional negative biases in the surface temperature fields, in the
version of the climate model used here.
The differences between the two future climate simulations and the current
climate simulation were used to predict the changes to air-quality that
might be expected in a future warmer climate, if anthropogenic precursor
emissions remain constant at their current levels, versus if the RCP 6
emissions controls were adopted. Metrics of concentration, human health, and
ecosystem damage were compared for the simulations. The scenario with future
climate and current anthropogenic emissions resulted in worse air-quality
than for current conditions – that is, the effect of climate-change alone,
all other factors being similar, would be a worsening of air-quality. These
effects are spatially inhomogeneous, with the magnitude and sign of the
changes varying with region. The scenario with future climate and RCP 6
emissions for 2050 resulted in an improved air-quality, with decreases in
key pollutant concentrations, in acute human mortality associated with
air-pollution, and in sulphur and ozone deposition to the ecosystem. The
positive outcomes of the RCP 6 emissions reductions were found to be of
greater magnitude than the negative outcomes of climate change alone. The
RCP 6 scenario however resulted in an increase in the deposition of
nitrogen, as a result of increased ammonia emissions expected in that
scenario, compared to current ammonia emissions levels.
The results of the study raise the possibility that simultaneous reductions
of greenhouse gases and air pollution precursors may further reduce air
pollution levels, with the added benefits of an immediate reduction in the
impacts of air pollution on human and ecosystem health. Further scenarios to
investigate this possibility are therefore recommended. |
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