Last year was one of the seven warmest years on record, despite the cooling effects of the natural ‘La Niña’ weather pattern, according to UN experts.
The World Meteorological Organisation (WMO) said a series of global datasets showed 2021 was the seventh year in a row where the temperature has been more than 1°C above pre-industrial levels.
An assessment collating the six datasets, including one compiled by the Met Office and the University of East Anglia (UEA), reveals that 2021 was around 1.1°C warmer than the 1850-1900 average.
This was despite the presence in 2020-2022 of La Niña events, a large-scale cooling of the ocean surface temperatures in parts of the Pacific Ocean and changes in tropical atmospheric circulation, which temporarily cool global temperatures.
The Met Office and UEA’s dataset puts 2021 as the joint sixth-warmest year on record, while other datasets put it between the fifth and seventh warmest, with small differences between the different analyses.
The WMO said global warming and other climate impacts were expected to continue due to heat-trapping greenhouse gases in the atmosphere which have continued to rise to new record highs.
Professor Petteri Taalas, WMO secretary-general, said: “Back-to-back La Niña events mean that 2021 warming was relatively less pronounced compared to recent years. Even so, 2021 was still warmer than previous years influenced by La Niña.
“The overall long-term warming as a result of greenhouse gas increases is now far larger than the year-to-year variability in global average temperatures caused by naturally occurring climate drivers.”
He added that 2021 would be remembered for record-shattering temperatures in Canada, deadly flooding in Asia and Europe and drought in parts of Africa and South America: “Climate change impacts and weather-related hazards had life-changing and devastating impacts on communities on every single continent.”
The warmest seven years on record have all occurred since 2015, with 2016, 2019 and 2020 the hottest three.
An exceptionally strong El Niño pattern, which has the reverse effect of a La Niña by pushing global temperatures up, occurred in late 2015 and continued into early 2016, helping propel the year into the hottest spot.
Dr Colin Morice of the Met Office said: “2021 is one of the warmest years on record, continuing a series of measurements of a world that is warming under the effects of greenhouse gas emissions. This extends a streak of notably warm years from 2015 to 2021 – the warmest seven years in over 170 years of measurements.”
Professor Tim Osborn of the University of East Anglia added: “Each year tends to be a little below or a little above the underlying long-term global warming. Global temperature data analysed by the Met Office and UEA’s Climatic Research Unit show 2021 was a little below, while 2020 had been a little above, the underlying warming trend.
“All years, including 2021, are consistent with long-standing predictions of warming due to human activities.”
Countries have agreed to take action to try to limit global warming to 1.5°C above pre-industrial levels to avoid the worst impacts of climate change, including more extreme floods, storms, heatwaves and damage to crops.
While nations meeting at the COP26 UN climate summit in Glasgow reaffirmed their commitment to striving to meet the 1.5°C limit, scientists have warned that much greater, faster cuts are needed in fossil fuel emissions and other pollutants that drive rising temperatures.
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