Concentrations of greenhouse gases in the Earth’s atmosphere reached record highs in 2021, a report by the United Nations’ weather agency said on Wednesday.

From 2020 to 2021, the atmospheric concentration of all three main greenhouse gases – carbon dioxide, methane and nitrous oxide – rose at a higher level than the average rate of the past decade, the report by the World Meteorological Organization said.

Greenhouse gases are gases in the atmosphere that trap heat. Scientists have said that human activity may be among the causes for the rising levels of these gases, and have expressed concern that this may be linked to global warming.

The global weather agency said on Wednesday that atmospheric carbon dioxide reached 149% of the pre-industrial level in 2021, and cited emissions from the combustion of fossil fuels and cement production as reasons for this. The organisation also said that methane levels recorded the highest year-on-year increase since systematic measurements began nearly 40 years ago.

The World Meteorological Organisation stated that concentrations of nitrous oxide increased at a slightly higher rate between 2020 and 2021 than between 2019 and 2020. It added that the rise in the concentration level of the gas between 2020 and 2021 was higher than the average annual growth rate over the past 10 years.

In 2021, carbon dioxide concentrations were recorded at 415.7 parts per million, methane at 1,908 parts per billion and nitrous oxide at 334.5 parts per billion. “These values constitute, respectively, 149%, 262% and 124% of pre-industrial levels before human activities started disrupting natural equilibrium of these gases in the atmosphere,” the report said.

The global weather agency noted that global carbon dioxide emissions have rebounded after the coronavirus-induced lockdowns of 2020.

The World Meteorological Organization’s Secretary-General Petteri Taalas said that the data underlines the enormous challenge and vital necessity to cut greenhouse gas emissions. “The continuing rise in concentrations of the main heat-trapping gases, including the record acceleration in methane levels, shows that we are heading in the wrong direction,” he said.

Taalas said that methane emissions can be reduced through cost-effective strategies, especially in the fossil fuel sector.

“However, methane has a relatively short lifetime of less than 10 years and so its impact on climate is reversible,” he said. “As the top and most urgent priority, we have to slash carbon dioxide emissions which are the main driver of climate change and associated extreme weather, and which will affect climate for thousands of years through polar ice loss, ocean warming and sea level rise.”