Last year was among the three hottest years on record and it rivalled 2016 as the hottest yet, the UN's World Meteorological Organisation said on Thursday.
UN Secretary General Antonio Guterres said the WMO’s analysis of five data sets showed again how climate change was the greatest threat facing mankind.
It was “another stark reminder of the relentless pace of climate change, which is destroying lives and livelihoods across our planet", Mr Guterres said.
In 2020, the planet endured sustained heat and bush fires in Siberia, low levels of Arctic sea ice and a record-breaking Atlantic hurricane season.
In the US, natural disasters cost the economy a record $22 billion, the WMO said.
Governments are not reducing emissions of carbon dioxide and other heat-trapping gases fast enough to meet targets agreed to in 2015 in Paris, the UN said.
The Paris accord aimed to keep global warming to less than 2°C above pre-industrial times and to strive to limit temperature increases to 1.5°C.
So far, temperatures have risen by 1.2°C and the planet is already “witnessing unprecedented weather extremes in every region and on every continent", Mr Guterres said.
“We are headed for a catastrophic temperature rise of 3°C to 5°C this century,” he said.
“Making peace with nature is the defining task of the 21st century.”
The WMO compiled data from the US National Oceanic and Atmospheric Administration, Nasa’s Goddard Institute for Space Studies, the UK’s Met Office Hadley Centre, the University of East Anglia’s Climatic Research Unit and other sources.