A global assessment of the effects of climate policy on the impacts of climate change

This study presents the first global-scale multi-sectoral regional assessment of the magnitude and uncertainty in the impacts of climate change avoided by emissions policies. The analysis suggests that the most stringent emissions policy considered here—which gives a 50% chance of remaining below a 2 °C temperature rise target—reduces impacts by 20–65% by 2100 relative to a ‘business-as-usual’ pathway which reaches 4 °C, and can delay impacts by several decades. The effects of mitigation policies vary between sectors and regions, and only a few are noticeable by 2030. The impacts avoided by 2100 are more strongly influenced by the date and level at which emissions peak than the rate of decline of emissions, with an earlier and lower emissions peak avoiding more impacts. The estimated proportion of impacts avoided at the global scale is relatively robust despite uncertainty in the spatial pattern of climate change, but the absolute amount of avoided impacts is considerably more variable and therefore uncertain.