Geneva | The past seven years (2015 – 2021) have been the warmest on record, although the La Niña weather phenomenon temporarily lowered temperatures last year, the World Meteorological Organization confirmed on Wednesday.
“The seven hottest years have all been recorded since 2015, with 2016, 2019 and 2020 topping the chart,” the WMO said in a statement, adding that “for the seventh consecutive year, global temperature exceeded more than 1 degree Celsius above pre-industrial levels.
“Global warming and other long-term climate change trends are expected to continue due to record levels of greenhouse gases in the atmosphere,” the Geneva-based UN organization added.
La Nina is not enough
“The long-term global warming due to the increase in greenhouse gases is now much greater than the annual variability in average global temperatures caused by natural climatic factors”, says WMO Secretary-General , Mr. Petteri Taalas, quoted in a press release.
Thus, if consecutive episodes of La Niña – which reappeared at the end of last year 2021 after an initial episode 2020-2021 – caused the warming of temperatures to be relatively less pronounced in 2021 than in recent years, 2021 “has still been warmer than those influenced by La Niña in the recent past,” Taalas explained.
The impact of La Nina, which occurs every two to seven years, is felt over a large part of the Earth in the form of variations in atmospheric pressure, winds and precipitation, with generally the opposite effects of a another phenomenon, El Nino.
In 2021, according to the WMO, the average temperature on the planet was therefore about 1.11 degrees Celsius higher, with a margin of error of plus or minus 0.13 degrees to its pre-industrial value, which corresponds to the period 1850-1900.
The Paris Climate Agreement aims to keep the increase in global average temperature well below 2 degrees Celsius above pre-industrial levels and if possible to 1.5 degrees.
The podium
To establish the most reliable statistics possible, the WMO synthesizes six major international data sets, in particular from the American Ocean and Atmospheric Administration (NOAA) or the European Center for Medium Weather Forecasts. term (ECMWF) and its Copernicus climate change monitoring service, which published similar findings last week.
The organization thus compiles millions of weather and ocean observation data, including satellite ones, with other modeled values to be able to “estimate temperatures at any time, anywhere in the world, even in regions where the network of observation is sparse, as in the vicinity of the poles”.
According to the various services on which the WMO bases its calculations, 2021 is the fifth hottest year on record (Copernicus), while NOAA and Berkeley Earth put it in sixth position and the Japanese meteorological services in seventh place.
In any case, “the year 2021 will be remembered due to a temperature record of almost 50°C recorded in Canada – a temperature comparable to the values recorded in the Sahara in Algeria – exceptional rainfall and deadly floods in Asia and Europe as well as episodes of drought in certain regions of Africa and South America”, recalls Mr. Taalas.
“The effects of climate change and weather-related hazards have had catastrophic consequences for people on all continents,” he said.