The mainstream scenario in this year’s outlook leads to at least 2.7ºC of warming. The Sustainable Development Scenario could limit warming 1.8ºC of warming by reaching net-zero emissions by 2070. That’s too late. Any temperature rise beyond 1.5ºC will exacerbate the devastation and injustice that is already too much to bear.

According to the letter, the outlook must provide governments, investors and companies with a scenario that includes measures such as exponential broad-spectrum renewable energy deployment, improved energy efficiency, electrification of cars, heating and heavy industry, an end to polluting combustion engines, and an end to the expansion of oil, gas and coal production, accompanied by a just transition and radical regeneration of nature.

The letter was initiated by Mission 2020, the organisation that strives for urgent action to limit the effects of the climate emergency.