ACPC Science Objective
The uncertainties about interactions between aerosols, clouds, precipitation, and climate (ACPC) are a fundamental limitation to our ability to understand past climate change and to project future warming reliably. This hampers the efforts of societies to optimally mitigate climate change, in pursuit of the goal to limit global warming to less than 2°C above pre-industrial levels.
The ACPC initiative aims at a better scientific understanding of these interactions at a fundamental level. The goal is to identify, disentangle, and quantify signals of impacts of aerosol perturbations on clouds, precipitation, and radiation, taking into account adjustments and feedback processes by synergistically exploiting observations and models across scales.
ACPC was initiated by IGAC, GEWEX and iLEAPS in 2007, with Meinrat Andreae (Max Planck Institute for Chemistry, Mainz, Germany) and Bjorn Stevens (Max Planck Institute for Meteorology, Hamburg, Germany) as co-chairs. This first phase ended in 2012. A main outcome was the comprehensive review paper by Rosenfeld et al. (Rev. Geophys. 2014; doi 10.1002/2013RG000441) ; other important publications that originate from ACPC discussions were Rosenfeld et al. (Science 2008; doi 10.1126/science.1160606) and Stevens and Feingold (Nature 2009; doi 10.1038/nature08281) .
The second phase of ACPC started in late 2013 with the current co-chairs, Daniel Rosenfeld (Hebrew University) and Johannes Quaas (University of Leipzig). Two workshops were conducted, in April 2015 at NASA-Goddard Institute for Space Studies in New York, and in April 2016 at the University of Oxford.
ACPC is currently supported by GEWEX and iLEAPS; both projects helped us to fund the participation of individual participants to the workshops, and with our public relations (iLEAPS hosts our web site, and we published our workshop reports in the GEWEX newsletter).