RESCUE Project Publication: “Ecological impacts of temperature overshoot: The journey and the destination”

To “overshoot” typically means to exceed or go beyond an intended target or limit. However, in the world of climate policy, where governments value flexibility, to overshoot increasingly means to exceed and then return to or go below an intended temperature limit, which in this case is a specified level of global warming. Increasing interest in a temperature overshoot is being driven by the fact that action to reduce greenhouse gas emissions remains insufficient to meet the Paris Agreement’s long-term goal of limiting global warming to 1.5°C or “well below” 2°C above pre-industrial levels. Indeed, the Intergovernmental Panel on Climate Change (IPCC) Special Report on 1.5°C found that the majority of emission scenarios limiting global warming to 1.5°C by 2100 already include a temperature overshoot.

A temperature overshoot pathway is like when a driver on a highway misses their exit and then has to work out how to still reach their intended destination. Many options might exist, some more dangerous than others; for example, making a U-turn by taking a later exit might be less dangerous than reversing up the highway.

In this article, output of the RESCUE project, the authors provide an overview of what is known so far about the potential ecological impacts of overshoot, the most critical knowledge gaps, and further research needed to address them.