Reversal of the impact chain for actionable climate information

Escalating impacts of climate change underscore the risk of crossing thresholds of socio-ecological systems and adaptation limits. However, limitations in the provision of actionable climate information may hinder an adequate response. Here we suggest a reversal of the traditional impact chain methodology as an end-user focused approach to link local climate risks to emission pathways. We outline the socio-economic and value judgment dimensions that can inform identification of such local risk thresholds and adaptation limits. We apply this approach to heat-mortality risks for the city of Berlin. To limit the likely maximum increase in the occurrence of heat days with expected health impacts to less than 50% compared to today, the remaining global carbon budget in 2020 is 700 Gt CO2. We argue that linking local risk threshold exceedance directly to global emission benchmarks can aid the understanding of the benefits of stringent emission reductions for societies and local decision-makers.