- Matt McGrath
- BBC News Science Reporter
One of the most surprising data from the recent UN report on climate change was the prominence of methane as a gas responsible for increasing temperatures.
An aggressive campaign to cut methane emissions could give the world more time to tackle climate change, experts say.
The Intergovernmental Panel on Climate Change (IPCC) report suggests that between 30% and 50% of the rise in temperatures is due to this powerful but short-lived gas.
The main sources of methane include agriculture, oil and gas fields and landfills.
For decades, the biggest efforts to tackle global warming have focused on limiting carbon dioxide (CO2) emissions from human activities such as energy generation or deforestation.
This is based on scientific evidence, as CO2 is responsible for about 70% of the increase in global warming that has occurred since the industrial revolution.
Methane (CH4), on the other hand, has not received this attention.
That may be changing, as a major United Nations study earlier this year highlighted its environmental impact.
Now, according to the IPCC report, methane is estimated to have added half a degree centigrade to global warming.
So where does all this gas come from?
About 40% of methane originates from natural sources such as wetlands, but most of it comes from a range of human activities.
“It’s a combination of origins, from agriculture — including livestock and rice cultivation — to the other major source of methane, which is garbage dumps,” says Professor Peter Thorne, one of the IPCC scientists at Maynooth University in Ireland .
“One of the main sources comes from the production, transport and use of natural gas, which has a misleading name, and should be called fossil gas,” he adds.
Since 2008, there has been a significant increase in methane emissions that researchers link to the boom in hydraulic fracturing, the method of oil exploration in parts of the US.
In 2019, methane in the atmosphere reached record levels, about two and a half times higher than in the pre-industrial era.
What worries scientists is that methane is a strong factor when it comes to climate warming. In a period of 100 years, it heats between 28 and 34 times more than CO2.
However, one good thing about CH4 is that it doesn’t last as long in air as CO2.
“If you emit a ton of methane today, in a decade you would expect only half a ton to remain in the atmosphere and in two decades, a quarter of a ton,” says Professor Thorne, adding:
“So basically, if we can stop our methane emissions by the end of the century, its presence in the atmosphere should return to natural levels, as they were in 1750.”
In the short term, experts believe that if methane emissions were to be reduced by 40-45% over the next decade, the temperature rise by 2040 could be limited to 0.3 degrees.
In a world where every fraction of a degree counts, this potentially makes a huge difference in this effort to keep global temperatures from rising more than 1.5 degrees.
What excites many researchers is the belief that a series of relatively simple actions can quickly help to limit methane production.
“It’s relatively cheap to limit some of your sources,” says Professor Euan Nisbet of London’s Royal Holloway University.
“In particular, we’re talking about leaks in the gas industry, which are now much easier to detect than they were 10 or 20 years ago because the instruments to detect them are so much better.”
“Some actions can be taken very quickly: in the tropics, you can put earth on top of huge urban landfills and you can also stop harvest residues from burning,” he adds.
These quick measures work. In the US, efforts to collect gas in landfills reduced methane emissions by 40% between 1990 and 2016.
In agriculture, there are also technical changes related to the management of waste and feed that can reduce emissions of this gas.
But achieving big reductions will require political action.
In countries like Ireland or New Zealand, where agriculture plays a key role in the economy, these changes can be problematic.
To be successful, these decisions must be fair and equitable.
“You can’t just tell people they can’t raise any more cows or sheep anymore,” says Professor Thorne.
“Policies are needed to help the transition to other means of land management, but that’s not going to happen if people say you can’t raise livestock anymore. It has to be a much more subtle approach.”
Consumer choice regarding their meat and dairy diet will undoubtedly have an impact in this sector.
The oil and gas industry also faces a major challenge in limiting methane.
Current laws have failed to stop the leaks. But there is growing interest from companies in the fossil fuel industry in using technology that can quickly identify these losses and eliminate them.
“If you look at it from an objective standpoint, the industry is improving on spills and incidents, but not fast enough,” says Arnel Santos, a veteran of the oil industry, first with Shell and now with the oil company. mCloud power technology.
“We need to move faster to show that we can really deploy technology to improve what we do, because the improvements so far aren’t fast enough compared to what we’re seeing,” he adds.
Perhaps the biggest change needed on the international stage is separating methane from other gases that cause warming.
As UN climate negotiators address all greenhouse gases in the same political process, there are concerns that they may make trade-offs, comparisons and compromises on methane that negate efforts to reduce those emissions.
Many are now calling for a separate process for methane, along the lines of the Montreal Protocol, which managed to bring countries together to regulate gases that have affected the ozone layer.
“To stop warming in the long term, we must stop carbon dioxide emissions,” said Professor Thorne.
“But to help us on this path, we could treat these gases differently. And if we could treat methane differently, we could buy time to adapt to the changes that are taking place.”
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