The Impact of Climate Change on Air Quality: the 4th ACCENT Barnsdale Expert Workshop

Climate change is already upon us – the first 2007 IPCC Scientific Report provides near certainty that it is happening together with ample evidence to show that it is induced by human activities. Climate change is a consequence of the increased concentrations of CO2 and other radiatively active trace gases together with particulate matter in the global atmosphere. The overall effect is to entrap energy in the lower atmosphere, increasing the average surface temperature, increasing the intensity of the circulation and probably changing the general pattern of the weather systems themselves, with direct consequences for us who live on the surface. Air quality depends the trace gas emissions from the biosphere and from human activities, the chemical reactions which govern the concentrations of trace species in the atmosphere, and on the temperature and the weather systems.. All these processes will be affected by the changes in temperature and circulation, so air quality is likely to be subject to appreciable changes as well. And this is added to the probable increases in human-produced emissions due to the necessary increases in industrial activity as we attempt to cope with the Earth's ever increasing population. While some qualitative effects of climate change on air quality can be imagined, the detailed response for any particular place or region is far from clear. In the future, the majority of the parameters within the models used to encompass our understanding of air quality will change as the climate changes, as will the emissions and the land use which governs many of them. Whether the models which have been developed and tested within the present climate are flexible enough to cope with the changes is, necessarily, an open question. Thus much intensive research work, both observational and modelling, will be required to ensure that our understanding keeps pace with the changes so that, if possible, more extreme consequences can be predicted and possibly avoided. It was within this context that the ACCENT 4th Barnsdale expert workshop on the Impact of Climate Change on Air Quality (CCAQ) was initiated. The workshop was held under the auspices of six ACCENT groups: Access to Emission Data, Access to Laboratory Data, Aerosols, Remote Sensing from Space (AT2), BIAFLUX, Modelling, and Transport and Transformation of Pollutants (T&TP). The meeting was held at the Barnsdale Hall Hotel in Rutland on Monday to Wednesday, the 5th to the 7th of November 2007. Some 45 experts attended. (Appendix 1). The meeting was organised around four discussion groups, addressing the major areas of concern. The workshop (Appendix 2) started with a plenary talk on each topic. The major part of the meeting was taken up with group discussions, the participants reassembling to consider the recommendations from each group. The speakers, chairs, rapporteurs and participants received detailed instructions to try to ensure that the discussions were as productive as possible (Appendix 3). The following conclusions and recommendations emerged from the three discussion groups