The first part of the Intergovernmental Panel on Climate Change’s (IPCC) fifth assessment report shows that global warming is “unequivocal” and human influence on the climate is clear.
Experts said the report was a “wake-up call” that activities such as burning fossil fuels would have a profound effect on society today and in the future and campaigners called for immediate action to cut greenhouse gas emissions.
The report, which has been published in Stockholm after line-by-line scrutiny by scientists and policymakers, found it is “extremely likely”, or 95 per cent certain, that the majority of the warming since the 1950s is down to human activity. The likelihood is up from a 90 per cent certainty in the last IPCC study in 2007.
Ice sheets are losing mass, glaciers are shrinking, sea ice cover has reduced in the Arctic and the permafrost is thawing in the northern hemisphere, the report – which draws on thousands of scientific papers – warns.
Temperatures are set to rise by more than 1.5C above pre-industrial levels by the end of the century without ambitious action to tackle emissions, and could rise by more than 4C if emissions continue to increase, the study found.