News & Analysis Physics World  June 2021

2020: Europe’s hottest year on record

Still warming up This year’s European State of the Climate Report finds that despite localized temporary reductions in air pollution, the COVID-19 pandemic has had a minimal impact on climate trends. (Courtesy: C3S/ECMWF)

Last year was the warmest on record for Europe, in part due to an exceptionally warm winter over the north-east of the continent. It was a year that saw wildfires rage in the Balkans and eastern Europe, while Storm Alex brought record rainfall and led to above-average river discharge across much of western Europe. These are among the key points in the European State of the Climate Report released in late April.

Published annually, the report brings together data from national meteorological bodies and the European Union’s Copernicus climate change service. The previous year’s weather conditions in Europe and the Arctic are analysed in the context of global climate trends, based on data from satellites, ground stations and computer modelling. “The report confirms, among other things, 2020 as the warmest year, winter and autumn on record for Europe with temperatures in winter 3.4 °C above the average,” says the report’s lead author Freja Vamborg, a climate scientist at Copernicus.

Despite localized temporary reductions in air pollution, the COVID-19 pandemic appears to have had minimal impact on climate trends. Preliminary estimates from satellite data indicate that global atmospheric carbon-dioxide levels increased by 0.6%, a slightly lower rate of increase than in recent years. Methane concentrations increased by 0.8% – a higher rate than recent years – which could be linked with melting permafrost in Siberia.

Perhaps the most alarming weather occurred in Arctic Siberia, where average temperatures were 4.3 °C above the 1981–2010 reference period, almost two degrees higher than the previous record. As a result, ice cover in the adjacent Arctic seas was at record lows for most of the summer and autumn. Regional snow cover was also reduced, which is likely to have further increased local warming with less solar energy being reflected off the white surfaces. “The Arctic really saw quite a spectacular year,” says Vamborg. “We know that the Arctic is warming at a faster rate than the global average. But on top of this long-term trend, the Arctic is also a very variable environment.” Vamborg says the short-term fluctuations mean it is not inevitable that next year will be equally extreme.

Europe’s climate report arrived a few days after the World Meteorological Organization (WMO) released its State of the Global Climate 2020 report, which stated that the average global temperature was 1.2 °C above pre-industrial levels. It was one of the three warmest years on record despite 2020 being a La Niña year when sea surface temperatures were cooler than average in the central and eastern tropical Pacific. The WMO report estimates that 50 million people were doubly hit in 2020 by extreme weather and the COVID-19 pandemic. Evacuations, recovery and relief operations were affected by the pandemic, highlighting the need for a more integrated approach to managing climate hazards. The pandemic has also revealed cracks in global food security, as movement of goods was restricted and weather forecast services that support agriculture in the developing world were compromised.

Both reports preceded the announcement by US president Joe Biden of an ambitious new commitment to reduce US greenhouse-gas emissions to at least 50% below 2005 levels by the end of this decade. Meanwhile, the UK government announced that it would set in law a target to cut carbon emissions by 78% by 2035 compared to 1990 levels.

James Dacey