Ringberg 2018

WCRP Grand Challenge Workshop: Bounding Aerosol Effective Radiative Forcing

Feb 25 - Mar 2, 2018

Schloss Ringberg
3700 Rottach-Egern, Germany



Nicolas Bellouin, Sandrine Bony, Olivier Boucher, Jean-Louis Dufresne, Piers Forster, Jim Haywood, Ulrike Lohmann, Gunnar Myhre, Johannes Quaas, Bjorn Stevens, and Philip Stier


Ringberg 2018 is the fourth of a series of workshops organized at Ringberg under the auspices of the World Climate Research Programmes (WCRP) Opens external link in current windowGrand Science Challenge on Clouds, Circulation and Climate Sensitivity and with the support of the Max Planck Institute for Meteorology in Hamburg, Germany and the Deutsche Forschungsgemeinschaft (DFG).

The aim of Ringberg 2018 is to revisit our understanding of aerosol effective radiative forcing, and to explore the physical hypotheses thought to exclude, or make unlikely, aerosol forcings exceeding a certain magnitude. For instance what are the arguments that make an aerosol forcing less negative than -1.5 (W/m^2) or a positive radiative forcing unlikely. Given the complexity of the aerosol, and its modes of interaction with the Earth System the workshop will focus on what we believe is likely, or unlikely, rather than attempting to quantify statements that incorporate a broader likelyhood interval.

The workshop will be organized — also through small breakout sessions — to advance discussion of specific ideas, particularly theses developed and submitted by participants before the meeting. Toward this end participants are invited to submit an up to 2 pages list of thesis underpinning their arguments why the aerosol effective radiative forcing is likely/unlikely aerosol to exceed a bound of their choice.

The following ideas guide the structuring of the workshop:

1. One presenter per session
- prepares a limited number of theses that quantify or constrain forcings/mechanisms
- all participants are invited to submit theses to the presentations
- theses can (should) be corroborated briefly by explanations/graphics/references
- presenters distribute the theses until late January so participants can prepare for the discussions

2. At the meeting, one rapporteur per session
- moderates the plenum discussions and
- takes notes for the wrap-up discussions on Friday

3. A large part of the discussions will be in breakout groups:
- three breakout groups with 10-12 participants each;
- distribution will be randomly selected and change each time, and
- a rapporteur per breakout group per session will also be randomly appointed

Scope, Preliminary programme, Participants  Initiates file download>>>(pdf)


Guests are free to arrive beginning Sunday afternoon, as the organizers/conveners will meet already on Sunday evening and Monday morning. The formal workshop proceedings will begin with lunch on Monday Feb 26 and the workshop will adjourn at 14:30 on Friday March 2. Friday afternoon everybody has to leave Ringberg, there is no possibility to stay until Saturday morning. Information describing how to get to Ringberg from either Munich main station or the airport is provided here: Initiates file download>>> (pdf). Additional information is also available on the Ringberg website: about travel Opens external link in current windowhere,  about lodging costs Opens external link in current windowhere


Nicolas Bellouin: Theses on the magnitude of ERFaer Initiates file download>>> (pdf)
Johannes Quaas: Theses on the magnitude of ERFaer Initiates file download>>> (pdf)
Steve Schwartz: Theses on the coupling of radiative forcing and climate sensitivity Initiates file download>>> (pdf)