Global temperature will exceed the 1.5°C threshold set by the Paris Agreement, very likely within the next few years. Under the most optimistic scenario, peak warming will reach 1.8°C above pre-industrial levels, although most scenarios project an increase of more than 2°C. As temperatures rise, climate risks and impacts will escalate to increasingly dangerous levels. This is the conclusion of Limiting Overshoot – Navigating exceedance of 1.5°C and pathways towards return, a report by the United Nations Environment Programme (UNEP), which considers that, in this situation, the best option is to exceed the 1.5°C limit for as short a time as possible, reach peak warming as soon as possible and then progressively bring global temperatures back below 1.5°C.

The key to minimising peak warming is to reduce greenhouse gas emissions immediately and sustainably, as well as to remove greenhouse gases through actions such as reforestation, agricultural practices and wetland restoration, among others. At the same time, adaptation measures are needed to reduce the vulnerability of societies, communities and economies to the impacts of climate change. However, the scope for adaptation is limited, and some impacts will be irreversible, especially if peak warming is not minimised.

The report calls for accelerated, collective and global action to move towards a pathway that makes it possible to exceed the 1.5°C threshold, reach peak warming as soon as possible and then begin bringing global temperatures down. How quickly and strongly action is taken will determine the scale and course of this pathway.

In the words of UN Secretary-General Antőnio Guterres, “This summer’s scorching heat, raging wildfires and deadly floods are a warning of what lies ahead. We must make the overshoot above 1.5 degrees as small and short as possible. That demands an overshoot of ambition.”