Assessing multiple environmental impacts of pollutant emissions: the global picture (*see related Grantham policy note published today*) by Apostolos Voulgarakis, Department of Physics, Imperial College London Imperial Earth Day, 21st of April 2017 Acknowledgements: Peter Steiglechner1,2, Mathew Kasoar1, Alyssa Gilbert1, Dilshad Shawki1, Laura Mansfield1,3 (+thanks to the Met Office for computing resources) 1Imperial College London, UK, 2FAU Erlangen-Nuremberg, Germany, 3University of Reading, UK

The pollution-climate complex: Source: US Climate Change Science Program.

Pollutants of relevance for global climate policy Key species: Sulphate (SO4) & Black Carbon (BC) IPCC 2013

Emission metrics Climate policy makers use metrics to evaluate and compare pollutants in terms of their impacts on global warming. Traditional metrics include the global warming potential (GWP), which is the only metric used in the Kyoto Protocol. IPCC 2013

Motivation Need metrics that go beyond just warming, capturing multiple environmental impacts of air pollutant emissions, such as on rainfall and air quality, as well as on temperature. Need metrics that can provide information on both global and regional environmental impacts of emissions from specific locations of the globe. Global air pollution-climate modelling experiments have recently been performed at Imperial College for the first time and will help achieve these aims.

Global impacts of regional emissions (See Grantham briefing note)

Regional impacts (European SO2) (See Grantham briefing note)

Regional impacts (European BC) (See Grantham briefing note)

Future challenges Include more pollutants in this framework. Include impacts on air quality/climate extremes. Calculate metrics based on emissions by economic activity sector instead of by species. Calculate such metrics with more models. Construct a unified metric that captures all impacts simultaneously. Differences in models’ RF is potentially compounded by existing differences in models’ climate sensitivities