With successive temperature records, the 2011-2020 decade will be the warmest since records, with the last six years since 2015 recording the highest temperatures, according to the World Meteorological Organization’s (WMO) provisional annual climate report. And "2020 was, unfortunately, another extraordinary year for our climate," lamented the secretary general of the UN agency, Petteri Taalas.
Between January and October, the global average temperature was about 1.2° C warmer than in the reference period 1850-1900, so 2020 is on track to become one of the three hottest years on record on the planet.
The WMO assessment is based on five data sets, which currently rank all 2020 as the second warmest year to date, after 2016 and before 2019. The difference between the three hottest years is small and the exact classification may change as soon as the data is available for the whole year.
"The years of record heat generally coincide with a strong El Niño episode, as was the case in 2016. [The phenomenon] La Niña tends to cool global temperatures, but the anomaly that appeared this year was not enough to slow the warming," Petteri Taalas said.
"Despite this anomaly, we are already experiencing almost record heat this year, comparable to the previous record for 2016," he noted. The WMO report also points to the probability that at least one in five of the global average temperatures will temporarily exceed 1.5°C by 2024.
However, one of the objectives of the Paris Agreement, signed in December 2015 by 195 countries, is to contain the rise in temperatures to 1.5° C compared to the pre-industrial era.
Extreme heat, fires, floods, increased ocean acidity, a record time of Atlantic hurricanes are just some of the signs that climate change has maintained its inexorable progression this year, "expanding the threats that the Covid-19 pandemic has weighed on both economic stability and human health and safety," the WMO warns.
The most notable records are those of North Asia, particularly in Siberia, where temperatures were more than 5° C above average. The heat in Siberia was strongest at the end of June, with 38.0° C recorded in Verkhoyansk on the 20th of that month, which is provisionally the highest temperature observed north of the Arctic Circle. The forest fire season, which devastated large areas of Australia, Siberia, the west coast of the United States and South America, was the most active in the last 18 years.
"Floods in parts of Africa and Southeast Asia have caused massive displacement and compromised the food security of millions of people," the agency's secretary general said. Arctic sea ice reached its annual low in September, placing second among the least extensive in 42 years of satellite observations. The extent of Antarctic sea ice in 2020, on the other hand, was similar to or slightly larger than the average for the past 42 years, while Greenland continued to lose mass, albeit at a slower pace than in 2019.
As for the oceans, which store more than 90 percent of the excess energy that accumulates in the climate system due to increased concentrations of greenhouse gases, it has become clear in recent decades that heat is absorbed more and more rapidly, the report points out.