Synthesis science working groups 

Descriptive title: Climate overshoot effects on land ecosystem functioning: a global data and model synthesis. Short title: CLOVER Principal investigators: Céline De Caluwé; Prof. Dr. Hugues Goosse; Prof. Dr. Wannes Hubau; Prof. Dr. Hans Verbeeck. PROJECT: Context According to the IPCC Special Report on global warming of 1.5°C, most emission scenarios that limit warming to 1.5°C by 2100 include a temperature overshoot period[1]. A temperature overshoot is defined as the temporary exceedance of a specified global warming level (e.g., 1.5°C) during a specified time period, followed by a decline to or below that level[2]. Such temperature overshoot pathways are achieved through anthropogenically enhanced CO2 removal from the atmosphere and storage, e.g., through negative emission technologies and geological CO2 storage, and the overshoot period often lasts multiple decades. As the implementation of greenhouse gas emissions reduction policies by governments are yet insufficient to limit global warming to 1.5°C or even 2°C, temperature overshoot pathways receive increasing attention from scientists and policy makers[3,4]. Summary and objectives The project aims to investigate the impacts of climate overshoot scenarios on ecosystems by integrating state-of-the-art modelling with observational data. It will leverage a newly developed AI-based emulator to bridge the gap between models and real-world data, allowing predictions of how ecosystems might respond to climate overshoot scenarios. To train and validate the emulator, data from experimental and modelling studies that experimentally modified one or more climatic variables, and long-term datasets such as the ICOS network and inventory plots, will be synthesized. The emulator will be tested on case studies in Western Europe and the Congo Basin to validate the findings, with a focus on policy-relevant outcomes. Finally, the project aims to co-create science-based recommendations and inform policy and societal responses to climate overshoot, ensuring a tangible impact beyond academic research. References [1]Rogelj J et al., 2018 Mitigation pathways compatible with 1.5°C in the context of sustainable development. In Global warming of 1.5°C. An IPCC special report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty (eds Masson-Delmotte V et al.). Cambridge, UK: Cambridge University Press. [2]Matthews JBR et al., 2021 Annex VII: Glossary. In Climate change 2021: The physical science basis. Contribution of working group I to the sixth assessment report of the Intergovernmental Panel on Climate Change (eds Masson-Delmotte V et al.), pp. 2215-2256. Cambridge, UK: Cambridge University Press. [3]Liu PR and Raftery AE, 2021. Country-based rate of emissions reductions should increase by 80% beyond nationally determined contributions to meet the 2C target. Communications earth & environment, 2(1), p.29. [4] Meyer AL, Bentley J, Odoulami RC, Pigot AL and Trisos CH, 2022. Risks to biodiversity from temperature overshoot pathways. Philosophical Transactions of the Royal Society B, 377(1857), p.20210394. Supported by: Belgian Climate Centre ​ Start date: October 2025 End date: To be confirmed