Planning for Change: Conservation-Related Impacts of Climate Overshoot

The Intergovernmental Panel on Climate Change's (IPCC) special report on global warming of 1.5 degrees Celsius (°C) makes clear that most scenarios (90%) that hold warming to 1.5°C by 2100 include an overshoot, or a period in which the temperature increase exceeds 1.5°C before declining to the end-of-century 1.5°C goal (IPCC 2018). An overshoot is also possible for 2°C scenarios, given the lack of ambition in existing mitigation commitments. Current conservation policy and planning does not adequately account for the high likelihood of a temperature overshoot in a 1.5°C scenario, but the impacts of an overshoot on conservation may be large. Efforts to avoid an overshoot must be increased through more ambitious mitigation commitments and a greater focus on peak warming rather than end-of-century outcomes. Simultaneously, conservation planning should account for such impacts by anticipating more dynamic systems that carry greater uncertainties and potentially irreversible changes that may persist even as temperatures peak and decline.