The rapid rise of atmospheric levels of carbon dioxide (CO2), methane and nitrous oxide has been continuing in 2022, observed the US National Oceanic and Atmospheric Administration (NOAA) scientists, with methane levels in the atmosphere more than two and a half times their pre-industrial level.
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.
Notably, 2022 marked 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.
Before 2013, scientists had never recorded three consecutive years of such high CO2 growth.
The 2022 methane increase was 14.0 ppb, the fourth-largest annual increase recorded since NOAA’s systematic measurements began in 1983.
Methane is a heat-trapping greenhouse gas less abundant than CO2 but which warms the Earth’s atmosphere much faster. It is the second biggest contributor to human-caused global warming after carbon dioxide and is responsible for about 25% of the heat trapped by all greenhouse gases.
Unlike carbon dioxide, which has sustained 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.
As much as 85% of the increase from 2006 to 2016 was ascribed to livestock, agriculture, human and agricultural waste, wetlands and other aquatic sources, a 2022 study by NOAA and NASA scientists finds. 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.
Levels of nitrous oxide, the third-most significant anthropogenic greenhouse gas, are now 24% higher than pre–industrial levels, following a 1.25 parts per billion (ppb) rise last year.
Fossil fuel-powered vehicles, including cars, buses, trucks, and farm machinery, are a major source of nitrous oxide, which is harmful to human health and water sources. But synthetic fertilisers and livestock manure from industrialised agriculture are the primary culprits behind rising nitrous oxide levels in recent decades.
“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.”
Last month, the Intergovernmental Panel on Climate Change, made up of the world’s leading climate scientists, delivered a “final warning” on rising greenhouse gas emissions that have pushed the world to the brink of irrevocable damage that only swift and drastic action can avert.