The handshake between the integrated assessment and climate modeling communities: IPCC AR5 as a catalyst for improved networking, collaboration and communication

In the wake of AR4, it was clear that there needed to be a much more proactive modeling strategy for the climate modeling community. In 2006 a series of conversations were initiated within the global environmental change communities about how to approach a modeling strategy for the next IPCC assessment (AR5). At that time, the idea of developing both a near- and long- term experimental design that addressed questions around carbon cycle diagnostics, Earth system predictability as well as inertia of the climate system were introduced. From these discussions, a joint meeting was held in Aspen, Colorado (Aspen Global Change Institute) that included both the climate and integrated assessment modeling communities as well as representatives from the impacts, adaptation and vulnerability (IAV) research groups. Many activities have been spawned from this initial set of conversations, including the development, for the first time ever, Representative Concentration Pathways (RCPs) which are a set of four radiative forcing pathways, of which three include, for the first time ever in IPCC history, mitigation for stabilization of greenhouse gasses and radiative forcings (mitigation scenarios include two stabilization and one overshoot and decline), a land use/land cover and emissions harmonization between integrated assessment and climate modeling communities as well as the near-term prediction experiment designed to address model skill in predictability, downscaling, extreme events, air quality, etc.. The consensus development of the RCPs provided an initial motivation for closer collaboration between the ESM, IAM and IAV communities towards the development of New Scenarios that were driven by the scientific communities and not the IPCC. These collaborations are leading to greater mutual understanding of modeling paradigms and strengthening ties with integrated assessment, climate and emissions inventory and modeling communities.