With the mission to synthesize earth system science for international climate policy, this topic focuses on two key questions, which are important for science and society alike:
1. What is the probability of key climate impacts under a particular emission pathway? And vice versa:
2. What are the implications for global and regional emissions, i.e., post-2012 negotiations, if a particular ecosystem climate impact or temperature level should be avoided with a given probability?
Recent advancements in observations and modeling of the climate system allow for the first time to derive probabilistic estimates across the cause-effect chain from emissions to impacts. PIK's expertise and capacity allows a unique approach to synthesize earth system science and to develop new methods for capturing the wealth of knowledge on each linkage between emis-sions, concentrations, forcing, global means and climate change patterns. For example, by com-bining emulations of AOGCM and ESM (using MAGICC) and large ensembles of an interme-diate complexity earth system model (CLIMBER-2), this project will be able to open new doors for probabilistic regional climate information, trying to overcome current difficulties in tradi-tional pattern scaling approaches with non-linear behaviors in climate patterns.
Schematic overview of the proposed topic linking regional modules of key climate impacts (upper right) and emission allocation options (upper left) via a probabilistic climate module (bottom). The probabilistic cli-mate module will entail a unique two-track approach, merging the advantages of AOGCM/ESM emulations (MAGICC) and an intermediate complexity model (CLIMBER-2).
Module 1: Emissions
This topic will investigate emission allocation options that are most likely to influence the post-2012 regime architecture, including Multi-Stage, the Brazilian proposal of historic responsibil-ity, the BASIC proposal, Full-Carbon Accounting and crediting for reduced emissions from de-forestation. Cooperation with LPJ will allow quantitative assessments of the latter two land use related architectural options, in order to determine 'allocation spaces' for fossil CO2 and other 'Kyoto-basket' greenhouse gas emissions. A comprehensive database with national emission inventories and projections will form the basis of this module. This module's key focus will be to fulfill "real-time" tasks during the negotiations - flexible enough to incorporate last-minute allocation proposals including their "real-world" amendments and exceptions. The module will take into account the probabilistic political determinants of emissions.
Module 2: Climate
PIK's expertise offers the unique opportunity to develop an embedded hierarchical model based approach to the synthesis of earth system science for policy relevant questions. With a model hierarchy starting with a rigorous emulation of the contemporary suite of AOGCM and Earth System Model models, performed by the simple climate model (SCM) MAGICC for global, hemispheric and land/ocean indicators and at the other end with a process based intermediate complexity model (EMIC) CLIMBER-2. While starting out with the readily tuned MAGICC, the fast CLIMBER-2 version will in parallel be further enriched, e.g. completing its regional scale gas-cycles, the module-integration and tuning of its parameter space. The key benefit of this two-model track approach is that the SCM's emulation power of AOGCMs and ability to perform probabilistic multiple-thousand-member ensembles in "real-time" will be merged with the enhanced physical realism of an EMIC, especially in regard to climate system properties outside the AOGCM/ESM emulation space, e.g. for high climate sensitivities, low emission pathways, large scale changes in systems such as sea ice or methane feedbacks. The further de-velopment of this 'probabilistic climate module' will focus in particular on emulating, con-straining and validating precipitation, sea-ice extent, thermohaline circulation, ocean acidifica-tion, circumpolar ocean temperatures, thermal seawater expansion and other sea level rise con-tributions.
Module 3: Pattern Scaling & Impacts
Climate change patterns (temperature, precipitation, cloudiness etc.) are key for regional cli-mate impact analysis as well as for carbon cycle, biosphere change and agro-economic model-ing. For scenarios not performed by AOGCMs, climate patterns were often scaled using their global means, although difficulties persist in particular in regard to the scalability of aerosol in-duced patterns, regions near sea-ice and snow margins, shorter than multi-decadal timescales, non-linearities for scaling extremes and the time-dependence of patterns under qualitatively dif-ferent forcing histories (e.g. peaking and declining scenarios). PRIMAP will attempt to fill this gap that arises as fine-pattern AOGCMs/ESMs simulations are restricted to a small set of multi-gas scenario ensembles. The two-track climate model approach will allow merging the benefits of traditional pattern-scaling using emulated global-mean temperatures from the SCM track with the more physically based, but coarser EMIC patterns in which non-linearities can be taken account of. This envisaged approach entails substantial new research, but potentially the high gain to come-up with a more reliable, flexible and comprehensive pattern scaling methodology than available so far. Core PIK products, such as LPJ, are vitally dependent on these patterns. Furthermore, the high-efficiency modules envisaged for PRIMAP will allow enhancing prob-abilistic regional climate predictions. Going beyond probabilistic regional climate patterns and their extreme statistics, RIMAP envisages completing the analysis chain to include key ecosys-tem impacts from an extensive literature database. As well, PRIMAP will be linked to existing (e.g. DIVA DINAS coast) or newly developed PIK impact modules.
Claudine Chen, Thomas Schneider von Deimling, Bill Hare (Co-Leader), Katja Frieler, Kathleen Markmann, Malte Meinshausen (Team Leader), Julia Nabel (alumni), Mahé Perrette, Joeri Rogelj, and Ben Poulter (alumni), Andrey Ganopolski, Eva Bauer, Sibyll Schaphoff
Malte Meinshausen via firstname.lastname@example.org, or Tel: +49 331 288 2652
Bill Hare via email@example.com, or Tel: +49 331 288 2412