Quantifying Local to Regional-Scale Climate Impacts using Global Mean Temperature Scenarios

English Abstract:

Assessing the potential impacts of climate change is essential to setting sound targets that minimize the costs and maximize the benefits of both adaptation and mitigation for society. Conventional wisdom, first codified in the UNFCCC’s 1992 agreement to stabilize greenhouse gas concentrations at levels that would prevent dangerous anthropogenic interference with the climate system, suggests that impacts are expected to scale with the magnitude of human emissions. Since then, further research has elucidated how the relationship between carbon emissions, global temperature, and impacts may be complicated by non-linear responses of the physical system to global forcing.

We present projected changes in a collection of CMIP5-based climate metrics based on high-resolution downscaled projections for North America that are relevant to climate impacts on infrastructure, natural resources, energy use, and human health. We then explore the extent to which many of these metrics scale with global temperature and hence carbon emissions at the local to regional scale. This novel approach, which combines multiple RCP scenarios and CMIP5 simulations into a single framework based on increases in global mean temperature (GMT) from +1 to +4°C, provides an unprecedented opportunity to connect local and regional impacts directly to global emission targets. With this methodology, we are able to explore the extent to which projected future changes in impact-relevant metrics scale with carbon-equivalent greenhouse gas emissions and global mean temperature, information which can in turn be used to distinguish between the implications of international climate targets under discussion at the UNFCCC Conference of Parties for individual nations, states, and even cities.