While rising carbon dioxide levels continue to be the primary driver of human-caused climate change, scientists from the US National Oceanic and Atmospheric Administration (NOAA) explained that methane traps more heat in the atmosphere and has a significant short-term influence on the rate of climate change.
NOAA’s analysis revealed that in 2021, atmospheric methane levels averaged 1,895.7 parts per billion (ppb) – about 162 per cent greater than pre-industrial levels.
They say the annual increase in atmospheric methane during this year was 17ppb – the largest annual increase recorded since systematic measurements began in 1983.
In comparison, NOAA scientists say the annual increase during 2020 was 15.3ppb.
The analysis also found that 2021 was the 10th consecutive year during which global carbon dioxide emissions increased by more than 2 parts per million (ppm), representing the fastest sustained rate of increase in the 63 years since monitoring began.
About 36 billion tons of carbon dioxide was emitted into the atmosphere last year by human activity and nearly 640 million tonnes of methane were emitted during the same period, according to scientists.
While the residence time of methane is approximately nine years, researchers say carbon dioxide would continue to warm the planet for thousands of years.
However, they add that methane is about 25 times more powerful at trapping heat in the atmosphere.
“Our data show that global emissions continue to move in the wrong direction at a rapid pace. The evidence is consistent, alarming and undeniable,” Rick Spinrad, NOAA Administrator, said in a statement.
“We need to build a Climate Ready Nation to adapt for what’s already here and prepare for what’s to come. At the same time, we can no longer afford to delay urgent and effective action needed to address the cause of the problem – greenhouse gas pollution,” Dr Spinrad added.
Atmospheric methane is generated by many different sources, including fossil fuel production, transport, and use, as well as the decay of organic matter in wetlands, and as a byproduct of digestion by ruminant animals like cows.
While estimating the exact sources responsible for variations in annual methane emission is complex, scientists say fossil fuel production and use could contribute to about 30 per cent of the total emissions of the greenhouse gas.
“Reducing methane emissions is an important tool we can use right now to lessen the impacts of climate change in the near term, and rapidly reduce the rate of warming,” Dr Spinrad said.
“Let’s not forget that methane also contributes to ground-level ozone formation, which causes roughly 500,000 premature deaths each year around the world,” he added.
Scientists raised concerns that an increase in biological methane, such as from wetlands and ruminant farming, may be the first signal of a feedback climate change loop that would largely be beyond humans’ ability to control.
“Reducing fossil methane emissions is a necessary step toward mitigating climate change,” NOAA scientist Xin Lan said in a statement.
“But the extreme longevity of the carbon dioxide emissions in the atmosphere means that we need to aggressively reduce fossil fuel pollution to zero as soon as possible if we want to avoid the worst impacts from a changing climate,” Dr Lan said.
Researchers expressed concerns that despite international pledges to reduce emissions, there has been no measurable progress in reducing greenhouse gas pollution.
“It’s going to take a lot of hard work to reverse these trends, and clearly that’s not happening,” Ariel Stein, director of the Global Monitoring Laboratory, said in a statement.
“So it is crucial that we continue to sustain integrated and robust monitoring and verification systems to help assess the current state of the atmospheric greenhouse gas burden, as well as determine the effectiveness of future greenhouse gas emission reduction measures,” Dr Stein said.
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