Human activity is changing the climate in unprecedented and sometimes irreversible ways, a major UN scientific report has said.
The landmark study warns of increasingly extreme heatwaves, droughts and flooding, and a key temperature limit being broken in just over a decade.
But scientists say a catastrophe can be avoided if the world acts fast.
There is hope that deep cuts in emissions of greenhouse gases could stabilise rising temperatures.
It leads a series of reports that will be published over the coming months and is the first major review of the science of climate change since 2013. Its release comes less than three months before a key climate summit in Glasgow known as COP26.
IPCC report key points:
It is “virtually certain” that hot extremes including heatwaves have become more frequent and more intense since the 1950s, while cold events have become less frequent and less severe.