Climate change impacts on human health over Europe through its effect on air quality

Abstract

This review examines the current literature on the effects of future emissions and climate change on particulate matter (PM) and O₃ air quality and on the consequent health impacts, with a focus on Europe. There is considerable literature on the effects of climate change on O₃ but fewer studies on the effects of climate change on PM concentrations. Under the latest Intergovernmental Panel on Climate Change (IPCC) 5th assessment report (AR5) Representative Concentration Pathways (RCPs), background O₃ entering Europe is expected to decrease under most scenarios due to higher water vapour concentrations in a warmer climate. However, under the extreme pathway RCP8.5 higher (more than double) methane (CH₄) abundances lead to increases in background O₃ that offset the O₃ decrease due to climate change especially for the 2100 period. Regionally, in polluted areas with high levels of nitrogen oxides (NO_x), elevated surface temperatures and humidities yield increases in surface O₃ - termed the O₃ climate penalty - especially in southern Europe. The O₃ response is larger for metrics that represent the higher end of the O₃ distribution, such as daily maximum O₃. Future changes in PM concentrations due to climate change are much less certain, although several recent studies also suggest a PM climate penalty due to high temperatures and humidity and reduced precipitation in northern mid-latitude land regions in 2100.A larger number of studies have examined both future climate and emissions changes under the RCP scenarios. Under these pathways the impact of emission changes on air quality out to the 2050s will be larger than that due to climate change, because of large reductions in emissions of O₃ and PM pollutant precursor emissions and the more limited climate change response itself. Climate change will also affect climate extreme events such as heatwaves. Air pollution episodes are associated with stagnation events and sometimes heat waves. Air quality during the 2003 heatwave over Europe has been examined in numerous studies and mechanisms for enhancing O₃ have been identified.There are few studies on health effects associated with climate change impacts alone on air quality, but these report higher O₃-related health burdens in polluted populated regions and greater PM_2.5 health burdens in these emission regions. Studies that examine the combined impacts of climate change and anthropogenic emissions change under the RCP scenarios report reductions in global and European premature O₃-respiratory related and PM mortalities arising from the large decreases in precursor emissions. Under RCP 8.5 the large increase in CH₄ leads to global and European excess O₃-respiratory related mortalities in 2100. For future health effects, besides uncertainty in future O₃ and particularly PM concentrations, there is also uncertainty in risk estimates such as effect modification by temperature on pollutant-response relationships and potential future adaptation that would alter exposure risk.

Keywords: Climate change and air pollution; Human health; Ozone; Particulate matter.

Fig. 1

The impacts of meteorological and climate variables on O₃ and PM concentrations as determined from studies in the literature. ↑ represents an increase in the variable and↓ a decrease. A Red (blue) box outlines depict where changes in a given variable predict an increase (decrease) in O₃ or PM

Fig. 2

Reproduction (with permission) of Figure 11.22 from chapter 11, IPCC WG1 Fifth Assessment Report (Kirtman et al. [74]) showing changes in surface O₃ (ppb) between year 2000 and 2030 driven by climate alone (CLIMATE; green) or emissions alone following CLE (black), MRF (gray), SRES (blue) and RCP (red) emission scenarios. Bars represents multi-model standard deviation with the exception of the green dotted bar over Europe, which represents the range of climate-only changes in summer daily maximum O₃ from a single-model study [43]. For further details, see Kirtman et al. [74]

Fig. 3

Adaptation (with permission) of Figures 11.23a and 11.23b from chapter 11, IPCC WG1 Fifth Assessment Report (Kirtman et al. [74]), showing European panels only. Projected changes in annual-mean (left) O₃ (ppbv) and (right) PM_2.5 (μg m⁻³) from 2000 to 2100 following the RCP scenarios (8.5 red, 6.0 orange, light blue 4.5, 2.6 dark blue) averaged over Europe (land). Coloured lines show the average and shading denotes the full range of 4 chemistry-climate models and coloured dots and vertical bars represent the average and full range of ~15 ACCMIP models for decadal time slices centred on 2010, 2030, 2050 and 2100. The average value and model standard deviation for the reference period is shown in the top of each panel for CMIP5 models (left) and ACCMIP models (right). For further details, see Kirtman et al. [74]