Levels of key heat-trapping gases in the atmosphere reached historic highs last year and are rising at a near-record pace, according to the U.S. National Oceanic and Atmospheric Administration.
Carbon dioxide, the most important and abundant of human-caused greenhouse gases, reached the third-highest amount in 2023 in its 65-year record-keeping history, NOAA announced Friday. Scientists are also concerned about the rapid increase in atmospheric levels of methane, a shorter-lived but more potent heat-trapping gas. Both have increased by 5.5% over the past decade.
The 2.8 parts per million increase in carbon dioxide levels in the air from January 2023 to December was not as high as the jumps in 2014 and 2015, but was larger than seen every year since definitive records began in 1959. The average carbon dioxide level for 2023 is 419.3 parts per million, an increase of 50% compared to pre-industrial times.
Methane’s jump of 11.1 parts per billion last year was lower than record annual increases from 2020 to 2022. Last year the average was 1922.6 per piece. It has increased by 3% in just the past five years, a faster increase than carbon dioxide, jumping 160% from pre-industrial levels, said Xin “Lindsay” Lan, a University of Colorado and NOAA atmospheric scientist who did the calculations.
“The decade-long rise of methane should alarm us,” said Rob Jackson, a Stanford University climate scientist who heads the Global Carbon Project, which tracks carbon dioxide emissions worldwide but was not part of NOAA’s report. “Fossil fuel pollution warms natural systems like wetlands and permafrost. As these ecosystems warm, they release even more greenhouse gases. “We are stuck between a rock and a charred ground.”
Methane emissions in the atmosphere come from natural wetlands, agriculture, livestock, landfills and leaks, and the intentional burning of natural gas in the oil and gas industry.
According to the International Energy Agency, methane is responsible for approximately 30% of the current increase in global temperature, with carbon dioxide responsible for twice as much. According to the U.S. Environmental Protection Agency, methane traps about 28 times the heat per molecule as carbon dioxide, but it remains in the atmosphere for decades or so rather than centuries or thousands of years like carbon dioxide.
Carbon dioxide and methane levels were higher in the ancient past, but that was before humans existed.
Nitrogen oxide, the third largest human-caused greenhouse gas, reached record levels last year, increasing by 1 part per billion, but the increases were not as high as in 2020 and 2021. from agriculture, burning fuels, fertilizer and industrial processes, according to the EPA.
“These numbers show that we still have much work to do to make meaningful progress in reducing the amount of greenhouse gases accumulating in the atmosphere,” NOAA Global Monitoring Laboratory Director Vanda Grubisic said in a statement.
Last year, companies around the world pledged to drastically cut methane emissions from the oil and gas industry — almost completely — with a new initiative that could reduce future temperature increases by as much as a tenth of a degree Celsius. And the EPA issued a final rule to reduce methane emissions produced by the oil and gas industry.
But in the past five years, methane levels have increased faster than ever before in NOAA’s records. And recent research has shown that government efforts to track methane vastly underestimate the pollution released into the air from the energy industry.
Lan said studies of certain methane isotopes in the air show that most of the increased methane comes from microbes, indicating that emissions from wetlands and perhaps agriculture and landfills are increasing, but not as much as from the energy industry.
“I’m still mostly concerned about carbon dioxide emissions,” Lan said.
Carbon dioxide emissions into the air from burning fossil fuels and cement making reached an all-time high of 36.8 billion metric tons last year, according to the Global Carbon Project; This is twice the amount emitted into the air 40 years ago. But about half of what comes out of smokestacks and exhaust pipes is temporarily absorbed and stored by trees and oceans, keeping it out of the atmosphere, Lan said.
Methane doesn’t have the temporary carbon storage that carbon dioxide has, Lan said.
Last year’s shift from a three-year La Nina to a warm El Nino, the natural cooling of the Central Pacific that changed weather patterns around the world, played a role in reducing the increasing proportion of methane in the air and raising carbon dioxide levels. aforementioned.
That’s because the bulk of methane emissions come from wetlands, which are wetter in much of the tropics during La Nina, creating more microbes in lush growth to release methane, Lan said. La Nina ended in the middle of last year and was replaced by a strong El Nino.
Carbon dioxide levels in the atmosphere tend to be higher during warm El Niños, but what’s available is starting to decrease, Lan said.
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