Our analysis addresses the fundamental question of to what degree global mean temperature change is an appropriate indicator for climate change impacts, because biophysical impacts may also be expected to depend on CO2 concentration, changes in precipitation patterns, rate of climate change, and inertia of the biophysical system. Based on projections already generated in a project called ISI-MIP (the Intersectoral Impact Model Intercomparison Project), we analysed to what degree is the relationship between global warming and biophysical impacts dependent upon the scenario.
We have developed simplified descriptions of changes in renewable water resources, water and carbon fluxes and stocks, and changes in crop yields. We have also created simplified descriptions (called emulators) of the trends in climatic range for ecosystem functioning and focusing on key regions identified from stakeholder dialogue. The resulting descriptions allow for highly efficient impact projections based on arbitrary temperature and CO2 concentration pathways.
The role of feedbacks from climate change impacts back to the climate system, for example the rate of decomposition of plant material (organic carbon) currently locked within permafrost peatlands and drying of rainforests, has been quantified through a range of tests.
Monitoring of present day climate extremes enabled us to test impact models against similar conditions to what might become usual at higher-end global warming. We analysed known changes in crop productivity, river flows and ecosystems with known changes in climate conditions of extreme temperature, precipitation, and CO2 changes.
We also focused on evaluating the ability of impact models to take into account effects of extreme events, such as the Amazon drought 2005 and 2010, Russian heatwave of 2010, Western European drought of 2003, US drought of 2011. Current extreme events and their weather data have enabled us to compare our model output of extreme events with the observed ecosystem relationships such as plant productivity to soil moisture deficit, river discharge to precipitation, crop yields to temperature and precipitation.
Further along in the timing of HELIX we did combine the data from WP2 and WP3 to merge our projections of biophysical impacts with the HELIX high resolution climate projections. We examined improved representations of extremes on river flows, water availability, crop productivity, ecosystems, and coastal flooding. Impacts also depend upon the degree of future adaptation to impacts, not only the climate conditions. We have also analysed adaptation options here, with specific attention to water, agriculture and biodiversity conservation. The conservation data is from the Wallace Initiative database. We identified refugia where the climate remains suitable for more than 75% of the species currently present, and ‘areas of concern’ where climatic suitability disappears for more than 75% of the species currently present. We then applied this ranking to map the adaptation effort required globally to protect biodiversity.