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Methane levels have seen a startling increase since the early 2020s, according to a new study. The potent greenhouse gas, known for its significant impact on global warming, has seen a “substantial” rise, with wetlands and fossil fuel emissions identified as the primary culprits.
In 2015-2019, methane growth rates were 7-10 parts per billion (ppb) per year, which jumped to roughly 12–18 ppb per year between 2020–2023, said the study published in journal Frontiers in Science.
Methane is responsible for roughly a third of the rise in global temperatures. The greenhouse gas is about 80 times more potent than carbon dioxide (CO2) in 20 years after it is released into the atmosphere.
Previous studies found an increase in lighter isotopes (variants) of atmospheric methane, which has a biogenic or natural origin.
“Increased methane emissions from wetlands appear likely to have driven a larger portion of the higher 2020–2022 growth rates,” the researchers wrote in their paper.
Wetland emissions can be attributed to microbes that consume organic material and produce methane as a byproduct.
The persistent La Niña pattern and cool phases of the El Niño-Southern Oscillation, also known as ENSO, may contribute to this phenomenon.
The combination of La Niña, anthropogenic warming and climate extremes may have led to increased wetland methane emissions compared to previous years.
In 2023, La Niña transitioned to El Niño, the warming phase of ENSO. This may have reduced the observed growth rate, indicating that La Niña played a role in the very high 2020–2022 methane growth rates. However, emissions appear to have remained much higher in 2023 compared to pre-2020 values.
In terms of fossil fuels, national reporting frequently ignores super-emitters, which are facilities that emit massive amounts of methane as a result of abnormal operational conditions. Recent advances in satellite remote sensing have identified hundreds of super-emitters.
“The United States Environmental Protection Agency does not account for ‘super-emitters’ — devices that emit anomalous amounts of methane because of malfunctioning equipment or poor operational practices,” Daniel J Jacob, professor at Harvard University and the study’s lead author, previously told Down To Earth.
The COVID-19 pandemic was also linked to increased methane emissions from the energy sector in early 2020. During lockdowns, researchers observed a decrease in nitrogen oxide (NOx) emissions from automobiles, trucks and other non-road vehicles, as well as industrial sources such as power plants, industrial boilers, cement kilns and turbines. NOx combines with ozone to form hydroxyl radicals, which destroy methane in the atmosphere.
Furthermore, it was unlikely that the waste or agriculture sectors would have contributed to increased emissions as the variations are minimal, the paper said. For example, global cattle numbers grew at an average rate of 1.1 per cent over the 2020-2022 period from a 0.9 per cent per year average over the 2015–2019 period.
The paper identified three main action imperatives, the first of which was to change course and reverse the growth of methane emissions.
The second step is to align methane and CO2 mitigation. The researchers stressed the importance of understanding how different countries’ methane reduction plans fit into the broader climate change mitigation agenda and the push for “Net Zero CO2.”
“Policies leading to rapid and deep cuts in both CO2 and methane provide the strongest benefits across the century,” read the paper.
Countries that successfully reduce CO2 without also reducing methane will experience increased warming. A delay in methane cuts from 2020-2040 would result in 4.2 million more premature deaths from ozone exposure by 2050. This greenhouse gas tends to increase surface ozone, an air pollutant.
The third imperative for action is to optimise methane abatement options and policies. Abatement technologies could cut 29-62 million tonnes (Mt) of methane per year in the oil and gas subsectors, 12-25 Mt per year in the coal subsector, 29-36 Mt per year in the waste sector and 6-9 Mt per year from rice cultivation in 2030.
For livestock, it ranges between 4 and 42 tonnes per year, depending on factors such as the assumed ability to adopt higher productivity breeds and reduce total animal numbers. This could be further enhanced with nascent technologies such as methane inhibitors for ruminants and cultured and alternative proteins.
The US, Canada, Russia, Saudi Arabia, Libya and 10 other countries have been identified as having the highest potential to mitigate methane emissions from oil and gas. Options include replacing a mechanical component with an advanced feature, installing additional units to prevent methane from escaping and monitoring and repairing facilities.
Some countries with large populations, such as India, Brazil and Mexico, have significant mitigation potential in landfills (waste sector), as do others with smaller populations, such as Azerbaijan, Poland, Peru and the United Arab Emirates. India, for instance, can benefit the most from energy generation, the study showed.
Cutting all methane emissions tomorrow would mean 90 per cent of accumulated methane — but only around 25 per cent of carbon dioxide—would have left the atmosphere over the next three decades.