It is yet another confirmation of the trend of recent years. The latest data released by the Copernicus climate change service (C3s) show that globally 2020 was the warmest year ever recorded, on a par with 2016. A year that closes the warmest decade (2011–2020), with a sharp surge in temperatures from 2015 to the present. According to the European Centre for Medium-Range Weather Forecasts, Europe experienced its warmest year ever recorded, 0.4°C above 2019, which had previously been the warmest year. CO2 emissions are also rising, albeit at a reduced rate compared to the previous year, reaching a peak of 413 ppm in May 2020.

"2020 stands out for its exceptional warmth in the Arctic and a record number of tropical storms in the North Atlantic," notes Carlo Buontempo, director of C3s. "It is no surprise that the last decade was the warmest on record and it is yet another reminder of the urgency of ambitious emissions reductions to prevent negative climate impacts in the future."

Arctic and Siberia, record temperatures

It is the northernmost areas of the planet, such as the Arctic and northern Siberia, that are recording significant increases with deviations from the average of 3°C, reaching even above 6°C. This is likely to have contributed to the fires that struck the Siberian region, detected by satellites as early as the beginning of May and which continued throughout the summer and well into autumn. As a result, the fires released a record quantity of 244 Mt (megatonnes, 1 Mt being equal to 1,000 tonnes) of carbon dioxide in 2020, more than a third higher than the 2019 record. During the second half of the year, Arctic sea ice was significantly below average for the time of year, with July and October seeing the lowest sea ice extent ever recorded for those months.

According to the measurements, the mean monthly sea ice extent in December 2020 was 11.7 million square kilometres (km²), approximately 1.1 million km² (or 0.9 per cent) below the 1981–2010 average. Overall, 2020 was the third lowest December on record, tied with December 2007, 2016 and 2017, and only slightly above the second lowest record, set in 2012.

"The extraordinary climate events of 2020 and the data from the Copernicus climate change service show us that we have no time to lose," comments Matthias Petschke, director at the European Commission for the Union's satellite navigation programmes, in a statement. "We must come together as a global community to ensure a just transition towards a net-zero future."

A record year for Europe too

In general, the entire Northern Hemisphere recorded above-average temperatures throughout the year, with the exception of one region of the North Atlantic. But it is Europe that is recording the greatest anomalies. Winter 2020, from December 2019 to February 2020, surpassed the previous warmest on record, set in 2016, by almost 1.4°C, while autumn (from September to November 2020) exceeded the previous record set in 2006 by 0.4°C. In addition, western Europe experienced a significant heatwave between the end of July and the beginning of August. The subsequent four warmest years for Europe also occurred within the last decade.

CO2 emissions on the rise

Despite the pandemic having affected the quantity of greenhouse gas emissions in the atmosphere for most of the year, we know that this reduction will have only a mild effect on atmospheric CO2 concentrations, given that annual variations are linked to natural cycles. C3s reports that, according to estimates by the Global carbon project, there was a reduction of around 7 per cent in CO2 emissions from fossil sources.

"Although carbon dioxide concentrations increased less in 2020 than in 2019, this is no cause for complacency," confirms Vincent-Henri Peuch, director of the Copernicus atmosphere monitoring service, in the official statement. "Until global net emissions are reduced to zero, CO2 will continue to accumulate in the atmosphere, driving climate change."