NOAA: Greenhouse gases spiked in 2021, with a record methane jump

For the second straight year, scientists at the National Oceanic and Atmospheric Administration (NOAA) are reporting a record increase in the level of methane in the atmosphere, along with a significant jump in carbon dioxide (CO2) levels.

Why it matters: These are the two most important greenhouse gases, with CO2 lasting in the air for centuries to millennia, and methane, which is a stronger warming agent, exerting its warming influence on the timescale of about a decade.

By the numbers: NOAA's preliminary analysis of global warming gases in 2021, released Thursday, is based on measurements taken at monitoring stations around the globe. It finds that the annual spike in atmospheric methane during 2021 was 17 parts per billion.

• This was the largest annual increase recorded since such tracking began in 1983. It beat the previous record set in 2020, which was 15.3 ppb.
• According to NOAA, atmospheric methane levels are now about 162% greater than they were during the pre-industrial era.
• Carbon dioxide levels increased by 2.66 parts per million during 2021, NOAA found, which made 2021 the 10th straight year that the levels of this long-lived global warming pollutant increased by more than 2 ppm -- "the fastest sustained rate of increase" since instrument monitoring began 63 years ago, the agency said in a statement.
• The last time CO2 levels were this high was between about 4.1 and 4.5 million years ago, when sea levels were about 75 feet higher than they are now.

Context: The numbers can seem abstract, Pieter Tans, a NOAA senior scientist told Axios, but they correspond to climate impacts on society and ecosystems worldwide, from extreme weather events to sea levels rising.

• He has been studying climate change since he was a graduate student in the Netherlands in the 1970s, and told Axios that as he watches levels of planet-warming gases build up faster, the more he worries about his grandchildren and the planet they are growing up on.

What they're saying: “Our data show that global emissions continue to move in the wrong direction at a rapid pace,”said NOAA administrator Rick Spinrad, in a statement. “The evidence is consistent, alarming, and undeniable."

The intrigue: There has been considerable scientific debate, which is not yet settled, on what has been causing methane levels to increase significantly during the past several years.

• According to Xin Lan, a scientist working at NOAA’s Global Monitoring Laboratory in Boulder, Colo., fossil fuels, including its production and use, accounts for about 30% of the total methane emissions.

• She told Axios that, along with other researchers, she thinks tropical wetlands and ruminant agriculture, such as cattle, are causing the majority of the emissions spike. However, there may be a feedback between human-caused global warming and an uptick in tropical rainfall, which might drive methane levels higher in future years.
• This could further accelerate warming.

The big picture: Countries and companies have banded together in recent months to commit to reducing methane emissions, including via the Global Methane Pledge signed at the COP26 climate summit in Glasgow. This is in part to address near-term warming while longer-term warming from CO2 is tackled in other ways.

• Pieter Tans, a senior scientist at NOAA's Global Monitoring Lab, told Axios the need for methane emissions reductions could overshadow the urgency of cutting CO2.
• "Doing something about methane is great. But it's just the first baby step," Tans said. "I hope if the emphasis on methane won't be used as an excuse for not doing much about co2," Tans said.

Editor's note: This story has been corrected to note that carbon dioxide levels increased by 2.66 parts per million during 2021, not 2.33 parts per million as NOAA originally reported.