by Levels of key heat-trapping gases in the atmosphere reached historic highs last year, growing at near-record rapid speeds, according to the US National Oceanic and Atmospheric Administration.
Carbon dioxide, the most important and most abundant of the human-caused greenhouse gases, rose in 2023 by the third-highest amount in 65 years of record-keeping, NOAA announced Friday. Scientists are also concerned about the rapid rise in atmospheric levels of methane, a shorter-lived but more powerful heat-trapping gas. Both have jumped 5.5% over the past decade.
The 2.8 parts per million increase in airborne carbon dioxide levels from January 2023 to December was not as high as the jumps in 2014 and 2015, but was greater than in any other year since 1959, when emissions began accurate records. The average level of carbon dioxide for 2023 was 419.3 parts per million, a 50% increase over pre-industrial times.
Last year’s methane jump of 11.1 parts per billion was lower than the largest annual increases on record from 2020 to 2022. It averaged 1922.6 parts per billion last year. It has risen 3% over the past five years and jumped 160% from pre-industrial levels showing rates of increase faster than carbon dioxide, said Xin “Linsday” Lan, the University of Colorado and NOAA atmospheric scientist who did the calculations.
“A ten-year spike in methane should scare us,” said Stanford University climate scientist Rob Jackson, who heads the Global Carbon Project which tracks carbon dioxide emissions around the world but didn’t. part of the NOAA report. “Fossil fuel pollution is warming natural systems like wetlands and permafrost. Those ecosystems are releasing even more greenhouse gases as they warm. We are caught between a rock and a charred place.”
Methane emissions into the atmosphere come from natural wetlands, agriculture, livestock, landfills and leaks and the intentional flaring of natural gas in the oil and gas industry.
Methane is responsible for about 30% of the current rise in global temperatures, while carbon dioxide is to blame for about twice as much, according to the International Energy Agency. Methane absorbs about 28 times the heat per molecule as carbon dioxide but lasts a decade or so in the atmosphere instead of hundreds or thousands of years like carbon dioxide, according to the Environmental Protection Agency the US.
Carbon dioxide and methane levels were higher in the past, but it was before humans were there.
The third largest man-made greenhouse gas, nitrous oxide, jumped 1 part per billion last year to record levels, but the increases were not as high as those in 2020 and 2021. Nitrous oxide, which lasts about a century in the atmosphere. from agriculture, burning fuels, manure and industrial processes, according to the EPA.
“As these numbers show we still have a lot of work to do to make meaningful progress in reducing the amount of greenhouse gases accumulating in the atmosphere,” said Vanda Grubisic, Director of NOAA’s Global Monitoring Laboratory, in a statement.
Companies around the globe last year pledged huge cuts – almost complete – on methane emissions from the oil and gas industry in a new initiative that could cut future temperature rises by a tenth of a degree Celsius. And the EPA issued a final rule to reduce methane emissions generated in the oil and gas industry.
But over the past five years, methane levels have risen faster than at any time in NOAA’s record keeping. And recent studies have shown that government efforts to track methane are overestimating the pollution that enters the air from the energy industry.
Studies of the specific isotopes of methane in the air show that much of the methane increase is from microbes, pointing to spiking emissions from wetlands and possibly agriculture and landfills, but not so much the energy industry, Lan said.
“I’m even more concerned about carbon dioxide emissions,” Lan said.
Emissions of carbon dioxide entering the air from burning fossil fuels and cement hit a record high last year of 36.8 billion metric tons, double the amount poured into the air 40 years ago, according to the Global Carbon Project . But trees and oceans temporarily absorb and store about half of what comes from smokestacks and tailings, keeping it out of the atmosphere, Lan said.
Methane doesn’t have that temporary carbon storage that carbon dioxide does, Lan said.
The change last year from a three-year La Nina, a natural cooling of parts of the central Pacific Ocean that changes weather around the world, to a warm El Nino, played a role in slowing the rate of increase of methane in the air and spiking carbon dioxide levels , Lan said.
That’s because the biggest methane emissions come from wetlands, which are wetter in much of the tropics during La Nina, creating more microbes in the lush growth to release methane, Lan said. The La Nina ended in the middle of last year, giving way to a strong El Nino.
Atmospheric carbon dioxide levels tend to rise higher during warmer El Ninos, but the current one is starting to worsen, Lan said.
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