Report warns temperatures likely to rise by more than 1.5C bringing widespread extreme weather.
Human activity is changing the Earth's climate in ways "unprecedented" in thousands or hundreds of thousands of years, with some of the changes now inevitable and "irreversible", climate scientists have warned.
Within the next two decades, temperatures are likely to rise by more than 1.5C above pre-industrial levels, breaching the ambition of the 2015 Paris climate agreement, and bringing widespread devastation and extreme weather.
Only rapid and drastic reductions in greenhouse gases in this decade can prevent such climate breakdown, with every fraction of a degree of further heating likely to compound the accelerating effects, according to the International Panel on Climate Change, the world's leading authority on climate science.