The Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP) is designed to bring together state-of-the-art knowledge of the biophysical and socio-economic impacts of climate change at different spatial scales, with an unprecedented level of consistency and coverage.
Whilst similar activities are already well established in the global climate modelling (Coupled Model Intercomparison Project, CMIP) and economic modelling communities (e.g. organized within the Integrated Assessment Modelling Consortium, IAMC), robust, spatially explicit, multi-model projections of climate change impacts are rare and generally not consistently coordinated across sectors. However, such consistent projections are essential to establishing a coherent path of exploration from the changing climate to societal costs. To fill this gap ISI-MIP will maintain a public repository of climate impact projections based on common climate and socio-economic scenarios, providing a comprehensive and consistent picture of the world at different levels of global warming. As the economic quantification of the costs of climate change turns from highly simplified global damage functions to a more detailed and spatially explicit representation of damages, the ISI-MIP repository is intended to provide a consistent basis for economic modeling activities. Just as impact simulations make use of the CMIP climate projections, future economic assessments of climate change impacts are invited to utilise the ISI-MIP repository as an input source.
ISI-MIP also provides an unprecedented opportunity to quantify potentially severe impacts resulting from cross-sectoral interactions, such as the impact of fresh water availability on agricultural productivity, or the loss of natural vegetation (and therefore carbon sinks) due to expansion of crop land. Furthermore, collaborations with the economic modelling community are ensuring that the ISI-MIP results provide the necessary input for models that calculate the monetary costs of multi-sectoral climate impacts.
In addition, the use of multi-model ensembles at each level and in each sector further allows for a systematic quantification of the uncertainties associated with climate impact projections, and their attribution to different stages of the modelling chain. Importantly, such a comprehensive set of consistent model simulations makes it possible to investigate the origins of model discrepancies and model deficits, identify the corresponding processes and/or parameters, and develop the models further. This promises to lead to significant improvement in modelling skill, in the same way the CMIP exercises lead to major advances in climate modelling skill. In ISI-MIP, model improvements will additionally be fostered through coordinated model validation exercises and the comparison of global and regional simulations.
The upcoming review of the 2°C target by the UNFCCC in 2015 highlights the central
3
importance of quantifying both the magnitude and uncertainty in the differential impacts of global temperature rise. ISI-MIP is aimed at providing the international research and decision-making communities with the information required to address the urgent challenges of global warming.
