Scientists Puzzled by Soaring Global Methane Levels
Methane concentrations in the Earth's atmosphere are soaring—and the exact causes of the "frightening" increase are puzzling scientists.
In April 2022, the National Oceanic and Atmospheric Administration (NOAA) reported that concentrations of the gas averaged 1,895.7 parts per billion (ppb) over the past year, a new record.
In fact, the NOAA report showed that 2021 saw a rise of 17 ppb: the largest annual increase in atmospheric methane levels since systematic measurements began in 1983.
"Methane concentrations are increasing at a frightening and totally unexpected rate," NASA atmospheric scientist Benjamin Poulter told Newsweek.
"In 2020 and again in 2021, methane concentrations grew at a rate that was more than double the average over the previous decade."
Scientists say the rapid rise in atmospheric methane has significant implications because it is a potent greenhouse gas and can contribute to global warming.
While methane lingers in the atmosphere for only around 10 years or so—far shorter than carbon dioxide—it has a warming potential roughly 30 times that of CO2.
As a result, soaring atmospheric methane concentrations is "serious and a major global problem," that could put at risk the goal of limiting global warming to to 1.5–2 degrees Celsius above pre-industrial levels, Euan Nisbet, an Earth scientist at Royal Holloway, University of London, in the United Kingdom, told Newsweek.
"Methane is a major anthropogenic greenhouse gas, and its unexpected recent rise is arguably the largest deviation from the hopes of the Paris Agreement (note the recent CO2 rise was also bad). If we don't get methane under control, the Paris Agreement will fail."
Since the era of the Industrial Revolution, methane concentrations in the atmosphere had been steadily increasing in a trend "clearly" driven by fossil fuel emissions—i.e. the burning of coal, gas and oil—according to Nisbet.
But in the 1990s, this increase began to slow and levelled off entirely between around 1999 and 2006. Then, in 2007, atmospheric methane levels began to spike mysteriously again and have been increasing ever since in a trend that scientists are struggling to properly understand.