Last year tied with 2016 as the world's warmest on record, rounding off the hottest decade globally as the impacts of climate change intensified, the European Union's Copernicus earth observation service said yesterday.
In the United States, the warmer temperatures contributed to a record 22 separate disasters that each caused more than a billion dollars of damage, including wildfires and hurricanes, according to a new US government report.
Meanwhile, the fingerprints of climate change were also starkly visible in Europe, which experienced its hottest year on record in 2020, and in the Arctic and northern Siberia, which suffered extreme heatwaves and fires, Copernicus said.
With governments due to meet for a climate summit in Glasgow in November, the latest data prompted renewed calls for faster action to slash greenhouse gas emissions in line with the 2015 Paris Agreement to avoid catastrophic climate change.
"The key here is to - for every year and as quickly as possible - reduce the amount we emit, thus reducing the amount we actually add into the atmosphere," said Freja Vamborg, senior scientist at Copernicus.
In 2020, temperatures globally were an average of 1.25 degrees Celsius (2.7 degrees Fahrenheit) higher than in pre-industrial times, Copernicus said.
The Paris accord aims to cap the rise in temperatures to "well below" 2C and as close as possible to 1.5C to avoid the most devastating impacts of climate change.
The Arctic and northern Siberia continued to warm more quickly than the planet as a whole in 2020, with temperatures in parts of these regions averaging more than 6C above a 30-year average used as a baseline, Copernicus said.
The region also had an "unusually active" wildfire season, with fires poleward of the Arctic Circle releasing a record 244 million tonnes of CO2 in 2020, over a third more than in 2019.
Arctic sea ice continued to deplete, with July and October setting records for the lowest sea ice extent in that month.
In August, instruments documented the highest temperature ever reliably recorded, when a California heatwave pushed the temperature at Death Valley in the Mojave Desert up to 54.4C.
Record spate of disasters
Scientists said the latest data were consistent with growing evidence that climate change is likely to result in more intense hurricanes, fires, floods and other disasters.
In the United States, the 22 separate billion-dollar disasters comprised seven tropical cyclone events, 13 severe storm events, one drought and one wildfire event, according to the report published on Friday by the National Oceanic and Atmospheric Administration.
That total smashed the previous annual record of 16 such disasters in 2011 and 2017.
The combined costs for 2020 were $US95 billion ($NZ131.3b) in the United States - the fourth-highest total annual cost since 1980.
The three most costly events were Hurricane Laura ($US19b); record wildfires in the US West ($16.5b); and the August 'derecho,' a storm in the Midwest packing hurricane-force winds ($11b).
"We need another dictionary to help us describe how these extremes continue to play out and unfold year after year," said Adam Smith, a NOAA climate scientist who tracks billion-dollar disasters.
The extreme year in the US helped push up damages from natural disasters globally to $210b in 2020 from $166b the previous year, German reinsurer Munich Re said in a report published on Thursday.
The impacts were particularly punishing in developing countries, where the majority of losses from weather-related disasters are not covered by insurance, said Ernst Rauch, chief climate scientist at Munich Re.
"The consequence is that economic development, with all these economic shocks, is set back, is pushed back for years," Rauch said.
Although Covid-19 lockdowns meant global emissions of CO2 dipped in 2020 compared with recent years, the concentration of the gas accumulated in the atmosphere continued to rise.
Britain's Met Office forecast on Friday that CO2 concentrations in spring 2021 would hit levels 50 percent higher than before the industrial revolution, breaching a symbolic threshold for human impact on the climate.
"This is another grim milestone in the unrelenting rise of atmospheric CO2 concentration," Heather Graven, a climate scientist at Imperial College London, said.