Impacts of climate change on air pollution levels in the Northern Hemisphere with special focus on Europe and the Arctic

Abstract

Abstract. The response of a selected number of chemical species is inspected with respect to climate change. The coupled Atmosphere-Ocean General Circulation Model ECHAM4-OPYC3 is providing meteorological fields for the Chemical long-range Transport Model DEHM. Three selected decades (1990s, 2040s and 2090s) are inspected. The 1990s are used as a reference and validation period. In this decade an evaluation of the output from the DEHM model with ECHAM4-OPYC3 meteorology input data is carried out. The model results are tested against similar model simulations with MM5 meteorology and against observations from the EMEP monitoring sites in Europe.The test results from the validation period show that the overall statistics (e.g. mean values and standard deviations) are similar for the two simulations. However, as one would expect the model setup with climate input data fails to predict correctly the timing of the variability in the observations. The overall performance of the ECHAM4-OPYC3 setup as meteorological input to the DEHM model is shown to be acceptable according to the applied ranking method. It is concluded that running a chemical long-range transport model on data from a "free run" climate model is scientifically sound. From the model runs of the three decades, it is found that the overall trend detected in the evolution of the chemical species, is the same between the 1990 decade and the 2040 decade and between the 2040 decade and the 2090 decade, respectively.The dominating impacts from climate change on a large number of the chemical species are related to the predicted temperature increase. Throughout the 21th century the ECHAM4-OPYC3 projects a global mean temperature increase of 3 K with local maxima up to 11 K in the Arctic winter based on the IPCC A2 emission scenario. As a consequence of this temperature increase, the temperature dependent biogenic emission of isoprene is predicted to increase Correspondence to: G. B. Hedegaard (gbh@dmu.dk) significantly over land by the DEHM model. This leads to an increase in the O 3 production and together with an increase in water vapor to an increase in the number of free OH radicals. Furthermore this increase in the number of OH radicals contributes to a significant change in the typical life time of many species, since OH are participating in a large number of chemical reactions. It is e.g. found that more SO 2− 4 will be present in the future over the already polluted areas and this increase can be explained by an enhanced conversion of SO 2 to SO 2− 4 .

Decadal regional air quality simulations over Europe in present climate: near surface ozone sensitivity to external meteorological forcing

“…Meleux et al, 2007 in their study of summer European ozone reported that temperature driven increase in biogenic emissions appeared to enhance ozone production and isoprene was identified to be the most important chemical factor in the ozone sensitivity. The same conclusion was reached by Hedegaard et al (2008) with their modeling study of climate change on air pollution, suggesting that dominating impacts on a large number of species including ozone are related to temperature increase. Figure 4 (left panel) shows differences in near surface air temperature between the ECHAM and ERA run during winter.…”

“…Most of the studies investigating the future air quality projections were based on global Climate-Chemistry models or global climate models coupled to chemistry-transport models (Hauglustaine et al, 2005;Stevenson et al, 2006;Racherla and Adams, 2006;Hedegaard et al, 2008;Racherla and Adams, 2008 and references therein) and only few studies give emphasis on the regional scale future air-quality (Szopa et al, 2006;Meleux et al, 2007;Nolte et al, 2008;Kruger et al, 2008). This paper presents climate-air quality simulations over Europe on a decadal timescale with focus on the sensitivity of near surface ozone on the lateral meteorological boundary conditions constraining the climate model.…”

Evaluation of two isoprene emission models for use in a long-range air pollution model

“…For Europe, the measurements used for this evaluation originates from the EMEP measuring network, which includes a large number of chemical components. Details about the measurement period and the location of the measuring sites are presented in Hedegaard et al (2008). For the North American domain, the monitoring data of the hourly ozone concentrations are provided by the US Environmental Protection Agency (EPA).…”

Implementation and evaluation of online gas-phase chemistry within a regional climate model (RegCM-CHEM4)

“…Climate-chemistry interactions and the evolution of air quality over the coming decades depend on many factors, such as the growth of pollutant emissions due to worldwide economic development, localized emissions in high activity areas such as megacities, and changes in climatic factors such as temperature and precipitation. Many recent studies focusing on the impact of increased greenhouse gas concentrations on air quality have found an increase in tropospheric ozone as temperatures and greenhouse gas concentrations increase (e.g., Hogrefe et al, 2011;Andersson and Engard, 2010;Weaver et al, 2009;Zhang et al, 2008;Leibenspeger et al, 2008;Hedegaard et al, 2008;Meleux et al, 2007;Giorgi and Meleux, 2007;Forkel and Knoche, 2006;Stevenson et al, 2005;Langner et al, 2005). Specifically, ozone is an important component in the troposphere because (1) it is a leading indicator of poor air quality that adversely affects human health and natural ecosystems (e.g., WHO, 2003) and (2) has the ability to act as a greenhouse gas.…”