Jacinta Bowler
Jacinta Bowler is a science journalist at Cosmos.
They were published in the Best Australian Science Writing 2023.
The rapid rise of methane in the atmosphere is continuing with the US National Oceanic and Atmospheric Administration (NOAA) saying levels in the atmosphere are now more than two and a half times their pre-industrial level.
The graph for both methane and carbon dioxide is stark. Every year the dots rise and fall with the seasons, but the trend remains – always an upward slope.
NOAA has just released new numbers for the two gases, finding that in 2022 they ‘continued their historically high rates of growth in the atmosphere’.
The global surface average for CO2 rose by 2.13 parts per million (ppm) to 417.06 ppm, which makes atmospheric CO2 50% higher than pre-industrial levels.
They also note that 2022 was the 11th consecutive year CO2 increased by more than 2 ppm, the highest sustained rate of CO2 increases in the 65 years since monitoring began.
Methane – which is much less abundant but significantly more potent – has also increased.
The 2022 methane increase was 14.0 ppb, the fourth-largest annual increase recorded since NOAA’s systematic measurements began in 1983.
“The observations collected by NOAA scientists in 2022 show that greenhouse gas emissions continue to rise at an alarming pace and will persist in the atmosphere for thousands of years,” said Rick Spinrad, NOAA administrator.
“The time is now to address greenhouse gas pollution and to lower human-caused emissions.”
This graph shows the globally-averaged, monthly mean atmospheric methane abundance determined from marine surface sites since the inception of NOAA measurements starting in 1983. Credit: NOAA Global Monitoring Laboratory
NOAA doesn’t know why methane emissions are rising so rapidly.
Unlike carbon dioxide, which has continued on its upward trend for decades, atmospheric methane increased rapidly during the 1980s, nearly stabilised in the mid-1990s and early 2000s, then resumed a rapid rise in 2007, which it has continued till today.
A 2022 study by NOAA and NASA scientists suggests that as much as 85% of the increase from 2006 to 2016 was due to livestock, agriculture, human and agricultural waste, wetlands and other aquatic sources. The rest of the increase was attributed to increased fossil fuel emissions.
Researchers are investigating the possibility that climate change is causing wetlands to give off increasing methane emissions in a feedback loop.
You can read more about the NOAA figures here.