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| A farmer spreads nitrogen fertilizer on a wheat field in France. Three potent greenhouse gases, nitrogen, and methane, are closely linked to climate change. Photo: Pascal Rossignol/Reuters |
By David Gelles, NY Times Climate Forward, April 9, 2024
The extreme weather. The melting glaciers. The weirdly warm oceans. They’re all the product of global warming, which is being driven by the release of the three most important heat-trapping gases: carbon dioxide, methane, and nitrous oxide.
And, according to a new study from the National Oceanic and Atmospheric Administration, emissions of those three greenhouse gases continued to surge last year to historic highs.
Global average carbon dioxide concentrations jumped last year, “extending the highest sustained rate of CO2 increases” in NOAA’s 65 years of record-keeping. Methane and nitrous oxide levels also rose sharply last year. All this despite a wave of global policy measures and economic incentives designed to wean the world off fossil fuels.
These weren’t just one-off anomalies. In each case, the rising emissions continued a long-term trend. By analyzing more than 15,000 air samples from around the world, NOAA found that the upticks in emissions last year “were in line with the steep increases observed during the past decade.”
The result has been a series of profound changes to the planet in a remarkably short amount of time. “The amount of CO2 in the atmosphere today is comparable to where it was around 4.3 million years ago during the mid-Pliocene epoch,” the NOAA report found. That was when the “sea level was about 75 feet higher than today” and “large forests occupied areas of the Arctic that are now tundra.”
Carbon dioxide
Last year, humans spewed some 36.6 billion tons of CO2 into the atmosphere, the most ever. That number may well be higher this year.
The concentration of carbon dioxide in the atmosphere is now more than 50 percent higher than it was before the Industrial Revolution.
It’s no secret where all this carbon dioxide is coming from. The burning of oil, coal, and gas is the main source of CO2 emissions, and the use and production of fossil fuels continue to rise around the world, with the United States producing more oil and gas than ever before.
And even as the build-out of renewable energy is speeding up, the appetite for fossil fuels remains strong, in part because overall energy demand is soaring.
Fossil fuels aren’t the only source of carbon dioxide. The extraordinary forest fires that have charred Canada, Europe and Chile over the past year are also adding CO2 into the atmosphere. Yet even there, the vicious cycle of human-caused climate change is easy to see: Many of those fires were made worse because of the warming that has already occurred.
Methane
For a while, it looked like methane emissions were slowing down. After a rapid rise in atmospheric methane concentration during the 1980s, levels stabilized in the late 1990s and early 2000s. Then in 2007, they started rising again, and fast.
Researchers acknowledge they don’t fully understand what accounted for the relative stability of methane output and then its renewed growth. But what is clear is that methane emissions are booming today.
Last year saw the fifth-highest-ever jump in methane concentration since record-keeping began, and methane levels are now more than 160 percent higher than they were before the Industrial Revolution, according to NOAA. Methane is a particularly potent greenhouse gas; while it breaks down faster than carbon dioxide, it is more powerful at trapping heat in the atmosphere.
The vast majority of the increased methane emissions can be traced back to humanity’s insatiable appetite. Agriculture is the biggest source of methane emissions, according to the International Energy Agency, followed closely by the burning of fossil fuels.
Nitrous oxide
While carbon dioxide and methane are the two gases most commonly associated with climate change, nitrous oxide is another potent heat-trapping gas, and is also on the rise.
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