Danger zone: where will a 2C temperature rise leave our planet?

It was once thought almost impossible. Now scientists are warning of irreversible changes to the Earth's climate in just the next four years, writes James Tapper

- James Tapper

Global temperatures could rise as high as 1.9C above the pre-industrial average over the next five years, according to data from the UN's World Meteorological Organization (WMO) last week. It's the first time climate models have predicted such a large increase, and 2C is not out of the question.

The Paris agreement in 2015 aimed to limit the increase to 1.5C a threshold that was breached for the first time last year - while also setting the goal of keeping the rise "well below" 2C.

If temperatures were to reach 2C, there could be devastating consequences for marine life. The Intergovernmental Panel on Climate Change warned in 2018 that 99% of coral reefs would decline. Researchers at the University of East Anglia said 18% of the world's insects would lose almost half their habitats. And we would see more frequent floods, droughts and wildfires: the WMO's report on 2024, the hottest year on record, said 800,000 people were displaced after 151 extreme weather events.

How large a rise can we expect?

Surpassing 1.5C for a single year does not mean the original target of the Paris agreement is dead just yet. Meteorologists calculate averages over several years, and most say we are currently at 1.4C.

The WMO report says there's now a 70% chance that the average warming will rise by more than 1.5C between 2025 and 2029, with a strong possibility of a single year hitting 1.9C. That is a stark change from 2015, when the Paris agreement was struck in a mood of optimism. Back then, meteorologists thought there was a zero to 1% chance that a single year would exceed 1.5C in the subsequent five years.