According to a report by the EU’s Copernicus Climate Service published on Monday, the past year was the fifth warmest ever recorded in the world. The average temperatures were 1.1 to 1.2 degrees Celsius above the pre-industrial value. The past seven years have therefore been the warmest on record.
A major factor preventing a new global heat record in 2021 was the ongoing La Niña event. The climate phenomenon, the counterpart to El Niño, leads to a natural cooling in the equatorial Pacific and thus has a slightly cooling effect on the global temperature. It is expected to continue into the first few months of 2022.
According to the Copernicus team, methane levels in the atmosphere rose to a new record last year. The powerful greenhouse gas, whose warming effect is more than 80 times that of carbon dioxide, comes from natural sources such as swamps and from human activities such as oil and gas infrastructure, cattle farming, rice cultivation and landfills. Although the numerous sources make it difficult to say exactly where the greatest quantities of methane come from, there are new ways of tracking down emitters that were previously difficult to determine; Satellite and ground-based measurements can make the gas visible.
Unlike CO₂, methane is broken down in the atmosphere after around twelve years. The strong but temporary impact makes methane emissions an efficient lever to limit warming in the near future. For this reason, more than 100 countries committed to reducing methane emissions at the most recent UN climate summit in Glasgow, Scotland.
The heat worsened the forest fires around the Mediterranean.
While last year’s average temperature is below 2016, 2020, 2019 and 2017 and only slightly before 2015 and 2018, the overall trend is clear: every decade since the 1960s has been hotter than the previous one. “2021 was another year of extreme temperatures with the hottest summer in Europe, with heat waves in the Mediterranean, not to mention the unprecedented high temperatures in North America,” said Carlo Buontempo, director of Copernicus Climate Change Service. “These extreme events remind us strongly that we have to change something, work quickly and decisively towards a sustainable society and a reduction in net carbon emissions.”
July 2021 was the hottest single month worldwide that the US climate agency NOAA has ever recorded. A new European temperature record of 48.8 degrees Celsius, which has not yet been officially confirmed, was set in Sicily, which exceeded the previous record by 0.8 degrees. The heat worsened the forest fires around the Mediterranean. The west coast of North America experienced an extreme heat wave in June.
“We should see the record breaking events of 2021, like the heat wave in Canada and the flooding in Germany, as a slap in the face to wake politicians and the public to the urgency of the climate crisis,” says Rowan Sutton of the National Center for Atmospheric Science at the University of Reading. In addition, the continuing rise in greenhouse gases in the atmosphere shows that the underlying causes have still not been eliminated. The data are “another warning of what we’re doing to our home planet,” says Brian Hoskins of Imperial College London.
Carbon dioxide, the gas that has so far caused about three-quarters of the warming of the planet, also continued to rise. Its proportion in the atmosphere increased by 2.4 parts per million (ppm). The average value in the atmosphere in 2021 was 414.3 ppm, 50 percent more CO₂ than in pre-industrial times. The highest monthly mean concentration was reached in April 2021 with 416.1 ppm.