Role of Air Pollutants

Apart from carbon dioxide (CO2), the climate system is affected by other substances in the atmosphere with human sources, including non-CO2 greenhouse gases and air pollutants. Air pollutants have a much shorter residence time in the atmosphere than CO2. Long-term goals, like holding warming below 1.5 and 2°C, will be achieved more easily if those substances that have a net warming effect are reduced not too long before the peak in temperature is reached, probably during the second half of the 21st century. We study the extent to which reducing air pollutants can help achieving long-term climate goals.

Publications

Germany needs to phase coal out of its electricity sector by 2030 to meet its obligations under the Paris Agreement. This is earlier than the dates discussed so far by the Coal Commission, a body established to come up with a coal exit plan by the end of 2018.If Germany follows the Paris Agreement compatible pathway we propose here, it can also make significant steps towards meeting its 2020 emission reduction targets – something seen as impossible at the moment.Under a planned and structured coal phase out, energy security and reliability of electricity supply is not expected to be a major concern and will be manageable. As well as reduced health impacts, a coal exit from electricity generation by 2030 in Germany will bring added benefits in job creation, helping to smooth the transition to a zero-carbon energy system.  
Limiting global warming to 1.5 or 2.0°C requires strong mitigation of anthropogenic greenhouse gas (GHG) emissions. Concurrently, emissions of anthropogenic aerosols will decline, due to coemission with GHG, and measures to improve air quality. However, the combined climate effect of GHG and aerosol emissions over the industrial era is poorly constrained. This study shows the climate impacts from removing present-day anthropogenic aerosol emissions and compares them to the impacts from moderate GHG-dominated global warming.