Assessing Contributions of Major Emitters' Paris-Era Decisions to Future Temperature Extremes

The likelihood and severity of high-impact future temperature extremes can be reduced through climate change mitigation efforts. However, meeting the Paris Agreement warming limits requires notably stronger greenhouse gas emissions reduction efforts by major emitters than existing pledges. We examine the impact of Paris-era decision-making by the world's three largest greenhouse gas emitters (EU, USA, and China) on projected future extreme temperature events. Country-level contributions to the occurrence of future temperature extremes are calculated based on current emissions policies and sequential mitigation efforts, using a new metric called the Contribution to Excess Risk Ratio. We demonstrate the Contribution concept by applying it to extreme monthly temperature projections. In many regions, future extremes depend on the current and future carbon dioxide emissions reductions adopted by major emitters. By implementing stronger Paris-era climate pledges, major emitters can reduce the frequency of future extremes and their own calculated contributions to these temperature extremes.