Greenhouse gas levels have hit yet another record – here's why

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Carbon dioxide, methane and nitrous oxide reached record-high concentrations successful the ambiance successful 2021, including the largest recorded summation successful methane

Environment 26 October 2022

By James Dinneen

Smoking chimney of a ember powerfulness plant

Carbon dioxide, nitrous oxide and methane reached grounds precocious concentrations successful the ambiance successful 2021 and person continued to emergence done 2022.

Researchers astatine the World Meteorological Organization (WMO), a UN bureau that has published an annual greenhouse state bulletin since 2006, measured atmospheric concentrations of the cardinal greenhouse gases astatine much than 100 monitoring sites astir the world.

They recovered atmospheric c dioxide, liable for astir 66 per cent of planetary warming since 1750, accrued connected mean by 2.5 parts per cardinal to 415.5 parts per cardinal successful 2021. Nitrous oxide, responsible for astir 7 per cent of warming, accrued by 1.3 parts per cardinal to 334.5 parts per billion. These increases were somewhat higher than the mean year-to-year summation implicit the erstwhile decade.

Methane, liable for astir 16 per cent of warming, saw the largest single-year summation since researchers started keeping records 40 years ago. Between 2020 and 2021, atmospheric methane accrued by 18 parts per cardinal to scope 1908 parts per billion, much than 2 and fractional times pre-industrial levels.

“The continuing emergence successful concentrations of the main heat-trapping gases, including the grounds acceleration successful methane levels, shows that we are heading successful the incorrect direction,” Petteri Taalas, Secretary-General of the WMO, said successful a property release.

Steps to trim methane emissions should beryllium taken “without delay”, but reducing c dioxide emissions remains the apical precedence to debar the worst effects of clime change, said Taalas.

What is causing the grounds levels?

It is nary enigma astir what is down the emergence successful c dioxide and nitrous oxide. The summation successful c dioxide is chiefly from the continued burning of fossil fuels and cement production. The emergence successful nitrous oxide is primarily from nitrogen fertiliser, burning fossil fuels and respective concern processes. Significant earthy sources of nitrous oxide see microbes successful ungraded and the ocean.

But since methane concentrations started rising successful 2007, researchers person struggled to explicate why.

The largest anthropogenic sources of methane are livestock, lipid and state accumulation and discarded rotting successful landfills; 60 per cent of atmospheric methane comes from anthropogenic sources similar these. But determination are besides important earthy sources of methane, specified arsenic wetlands. The information that these sources often are overlapping – e.g., a dairy workplace adjacent a wetland – arsenic good arsenic a deficiency of data, marque it hard to separate precisely what is down the rise.

According to the WMO, the ratio of antithetic c isotopes successful atmospheric methane suggests a biologic source. Models of however methane is transported astir the ambiance further constrictive this down, suggesting that tropical wetlands could beryllium to blame, with the summation successful emissions perchance owed to warmer temperatures and changing precipitation. However, the WMO says the relation of that clime feedback remains uncertain.

Changes that impact however methane breaks down successful the ambiance mightiness besides contribute, though not capable to explicate the rise. The authors of the study constitute it volition instrumentality much modelling and cautious monitoring to ace the methane mystery.