Why the attention on methane is crucial: COP28 in the spotlight

The annual United Nations climate summit for this year, known as COP28, is currently gaining significant attention. In recent years, such an event would not have been as much in the limelight.

The reason for the heightened focus on COP can be attributed to the intensifying urgency to implement potent measures for minimising carbon emissions from fossil fuels and averting the impending climate catastrophe. As it stands, the world is not even close to achieving the goals set forth in the 2015 Paris Agreement, which aims at reducing greenhouse emissions substantially to restrict global warming to less than 2 degrees Celsius relative to preindustrial averages by 2100. The year 2023 has been declared the warmest year in history, with a surge in occurrences of extreme weather conditions, such as heatwaves, droughts, and floods. Furthermore, 2024 is expected to break the existing temperature records.

The messages emanating from COP28 are a blend of satisfying, exasperating and perplexing. It is certainly encouraging that the Loss and Damage Fund has been ratified by 198 countries, which is essentially a formal recognition by rich, high-emitting nations that they need to aid in mitigating the escalating expenses of climate change incurred by developing nations. However, the frustration lies in the fact that the wealthy nations' commitments up to this point equate to approximately $725 million, which is less than 0.2 percent of the yearly climate change-related losses suffered by developing countries.

My particular interest lies in the headlines revolving around methane. Evaluating the good versus bad news associated with the emissions of this secondary human-caused greenhouse gas is complex.

Methane is a potent climate-warming gas, having around 80 times the atmosphere-warming potential of carbon dioxide. The redeeming factor is that methane lasts in the atmosphere for only around a decade, while carbon dioxide can persist for up to 1,000 years. Consequently, any reductions in methane emissions can potentially result in rapid declines in atmospheric concentration.

The Global Methane Pledge, which was initiated at COP26 two years back, may have picked up some momentum, but it still lacks the endorsement of crucial high-emitting nations. Then there's the announcement made by 49 oil and gas firms on December 1 declaring that they plan to minimise methane leaks from their infrastructure to 'near zero' by 2030, which seems positive but has also been regarded as greenwashing.

The policy debates are unfolding against a shockingly unexpected increase in methane emissions over the last ten years not from humans but from natural sources, predominantly wetlands.

To comprehend all the news that's being reported, I had a conversation with Euan Nisbet, a geochemist at Royal Holloway, University of London in Egham.

Nisbet says Methane's levels are "rising very fast" and that it seems like the objectives of the Paris Agreement are likely to be unmet.

Despite the concerning rise in natural methane emissions, around 60 percent of the current methane emissions into the environment is still due to human activities. Methane not only leaks out of defective oil and gas pipelines or is expelled into the air during coal combustion, but agriculture, especially ruminant animals, and landfills are also significant contributors.

The Global Methane Pledge vows to reduce humans’ emissions by 30 percent by 2030. Launched in 2021 by the United States and the European Union, the pledge has been agreed to by 150 countries to date. The latest signee is Turkmenistan, which is a considerable emitter of methane. If all countries were to follow suit, it is genuinely plausible to significantly cut down global methane emissions, inching us closer to achieving the goals set by the Paris Agreement, as argued by Nisbet in a Dec. 8 editorial in Science.

Nevertheless, several of the world's largest methane emitters, such as China, India, Russia, Iran, and South Africa, have yet to sign the pledge. The most substantial sources of methane in China come from coal combustion, whereas, in India, it is produced by coal as well as waste piles and biomass fires. The annual methane emission from China alone is estimated at about 65 million metric tons, which is over two times that of the United States or India, the two next biggest emitters.

With just seven years remaining till the 2030 deadline, achieving the methane reduction targets of the global pledge would be quite challenging, but as per Nisbet, not unachievable.

Methane emissions into the Earth's atmosphere have risen significantly since approximately 2007. About 60 percent of the currently emitted methane comes from human sources, but emissions from wetlands, likely due to climate change repercussions, are also contributing to this increase.

There’s precedent for successfully making such steep cuts to methane in such a short time, he adds. During the 2000s, “there was a seven-year period where [the U.K. government] brought methane emissions down by 30 percent,” in large part by reducing emissions from landfills and gas leaks.

China has just released its own Methane Emissions Control Action Plan in November, alongside a joint commitment between China and the United States to take action on methane. That news sounds potentially promising, if not wholly reassuring, as the plan does not include a lot of concrete numbers, Nisbet says.

So, what about the oil and gas industry’s recent promise to address its leaky infrastructure? Such a promise also sounds positive on the face of it — leaky infrastructure is definitely the low-hanging fruit when it comes to reducing humans’ methane emissions to the atmosphere (SN: 2/3/22).

On the other hand, hundreds of scientific and environmental organizations have signed an open letter in response. The letter suggests that the oil and gas industry’ promise is just greenwashing, “a smokescreen to hide the reality that we need to phase out oil, gas and coal,” the letter states. Furthermore, many oil and gas companies may routinely abandon old, still-leaking wells — effectively eliminating those leaks from their company’s emissions roster without actually stopping them.

That said, addressing the leaks does have to be done, Nisbet says. “I’d love to shut down the coal industry quickly, but I’m aware of the enormous social problems that brings. It’s a very difficult thing to nuance. You can’t go cold turkey. We’ve got to wind it down in an intelligent and collaborative way. The best thing to do is to stop the crazy leaks and venting.”

Plugging the leaks as soon as possible has taken on an increasing urgency, Nisbet says, because of a stark rise in natural methane being emitted to the atmosphere. Why this rise is happening isn’t clear, but it seems to be some sort of climate change–related feedback, perhaps linked to changes in both temperature and precipitation.

That natural methane emissions bump was also not something that the architects of the Paris Agreement saw coming. Most of that rise has happened since the agreement was signed. From 1999 to 2006, atmospheric methane had spent several years in near-equilibrium — elevated due to human activities, but relatively stable. Then, in 2007, atmospheric methane concentrations began to increase. In 2013, there was a particularly sharp rise, and then again in 2020.

Much of that increase seems to have come from tropical wetlands. Over the past decade, researchers have tracked shifts in methane sources by measuring carbon-12 and carbon-13 in the gas. The ratio of those two forms of carbon in the methane varies significantly depending on the source of the gas. Fossil fuel-derived methane tends to have higher concentrations of carbon-13 relative to carbon-12; methane from wetlands or agriculture tends to be more enriched in carbon-12.

The recent spikes in natural methane are eerily reminiscent of ice core records of “glacial termination” events, times in Earth’s deep past when the world abruptly shifted from a glacial period to a period of rapid warming, Nisbet and others reported in June in Global Biogeochemical Cycles. Such glacial termination events are large-scale reorganizations of the ocean-atmosphere system, involving dramatic changes to the circulation of the global ocean, as well as to large climate patterns like the Indian Ocean Dipole (SN: 1/9/20).

“Is this comparable to the start of a termination event? It looks horribly like that,” Nisbet says. But “it may not be. It might be totally innocent.”

Right now, scientists are racing to understand what’s happening with the natural methane bump, and how exactly the increased emissions might be linked to climate change. But as we search for those answers, there is something that humans can and must do in the meantime, he says: Cut human emissions of the gas as much as possible, as fast as possible. “It’s very simple. When you’re in a hole, stop digging.”