Nature Climate Change

Langenbrunner, Baird

doi: 10.1038/s41558-020-0778-0pmid: N/A

Richler, Jenn

doi: 10.1038/s41558-020-0779-zpmid: N/A

Armarego-Marriott, Tegan

doi: 10.1038/s41558-020-0780-6pmid: N/A

Findlay, Alyssa

doi: 10.1038/s41558-020-0777-1pmid: N/A

McLaren, Duncan; Markusson, Nils

doi: 10.1038/s41558-020-0740-1pmid: N/A

The nature and framing of climate targets in international politics has changed substantially since their early expressions in the 1980s. Here, we describe their evolution in five phases—from ‘climate stabilization’ to specific ‘temperature outcomes’—co-evolving with wider climate politics and policy, modelling methods and scenarios, and technological promises (from nuclear power to carbon removal). We argue that this co-evolution has enabled policy prevarication, leaving mitigation poorly delivered, yet the technological promises often remain buried in the models used to inform policy. We conclude with a call to recognise and break this pattern to unleash more effective and just climate policy.

Wallingford, Piper D.; Morelli, Toni Lyn; Allen, Jenica M.; Beaury, Evelyn M.; Blumenthal, Dana M.; Bradley, Bethany A.; Dukes, Jeffrey S.; Early, Regan; Fusco, Emily J.; Goldberg, Deborah E.; Ibáñez, Inés; Laginhas, Brittany B.; Vilà, Montserrat; Sorte, Cascade J. B.

Hasegawa, Tomoko; Fujimori, Shinichiro; Havlík, Petr; Valin, Hugo; Bodirsky, Benjamin Leon; Doelman, Jonathan C.; Fellmann, Thomas; Kyle, Page; Koopman, Jason F. L.; Lotze-Campen, Hermann; Mason-D’Croz, Daniel; Müller, Christoph; Ochi, Yuki; Pérez Domínguez, Ignacio;

Lin, Meiyun; Horowitz, Larry W.; Xie, Yuanyu; Paulot, Fabien; Malyshev, Sergey; Shevliakova, Elena; Finco, Angelo; Gerosa, Giacomo; Kubistin, Dagmar; Pilegaard, Kim

doi: 10.1038/s41558-020-0743-ypmid: N/A

Reducing surface ozone to meet the European Union’s target for human health has proven challenging despite stringent controls on ozone precursor emissions over recent decades. The most extreme ozone pollution episodes are linked to heatwaves and droughts, which are increasing in frequency and intensity over Europe, with severe impacts on natural and human systems. Here, we use observations and Earth system model simulations for the period 1960–2018 to show that ecosystem–atmosphere interactions, especially reduced ozone removal by water-stressed vegetation, exacerbate ozone air pollution over Europe. These vegetation feedbacks worsen peak ozone episodes during European mega-droughts, such as the 2003 event, offsetting much of the air quality improvements gained from regional emissions controls. As the frequency of hot and dry summers is expected to increase over the coming decades, this climate penalty could be severe and therefore needs to be considered when designing clean air policy in the European Union.