Climate change: the ‘other’ gas is increasingly contributing to global warming | temper nature

A crackdown on methane emissions could give the world more time to tackle climate change, experts say.

The IPCC report states that between 30% and 50% of the rise in temperatures is due to this powerful but short-lived gas.

Major sources of methane include agriculture, oil and gas fields, and landfills.

• A UN report notes that recent man-made climate changes are unprecedented

For decades, the largest efforts to tackle global warming have focused on reducing carbon dioxide (CO2) emissions from human activities such as power generation or deforestation.

This is based on scientific evidence, as carbon dioxide is responsible for about 70% of the increase in global warming that has occurred since the Industrial Revolution.

On the other hand, methane (CH4) has not received such attention.

That may change, as a major UN study earlier this year highlighted its environmental impact.

Now, according to an Intergovernmental Panel on Climate Change report, it is estimated that methane has added half a degree Celsius 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 combination of human activities.

“It’s a mix of assets, from agriculture – including livestock and rice – to the other major source of methane, which is landfills,” says Professor Peter Thorne, an IPCC scientist at the University of Maynooth in Ireland.

He adds that “one of the main sources comes from the production, transportation and use of natural gas, which has a misleading name and should be called fossil gas.” Since 2008, there has been a significant increase in methane emissions that researchers have linked to the boom in hydraulic fracturing, the method of drilling for oil in parts of the United States.

In 2019, atmospheric methane reached record levels, two and a half times higher than in the pre-industrial era.

What scientists worry about is that methane is a powerful factor when it comes to climate warming. In a 100-year period, it warms between 28 and 34 times more than carbon dioxide.

However, the good thing about CH4 is that it doesn’t last as long in the air as carbon dioxide.

“If you released a ton of methane today, within 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 methane emissions by the end of the century, its presence in the atmosphere should return to normal levels, as it was in 1750.”

In the short term, experts believe that if methane emissions are reduced by 40-45% over the next decade, the warming by 2040 could be limited to 0.3 degrees.

In a world where every part of a degree matters, this would likely make a huge difference in the effort to prevent global temperatures from rising by more than 1.5 degrees.

What intrigues many researchers is the belief that a series of relatively simple actions can quickly help reduce methane production.

Restricting some of your sources is relatively cheap, says Professor Ewan Nisbet of Royal Holloway University of London.

“In particular, we’re talking about leaks in the gas industry, which are much easier to detect now than they were 10 or 20 years ago because the tools for detecting them are much better.”

“Some actions can be taken very quickly: In the tropics, you can lay the land on top of huge urban landfills and you can also prevent the burning of harvest residues,” he adds. These quick actions work. In the United States, efforts to collect gas in landfills cut methane emissions by 40% between 1990 and 2016.

In agriculture, there are also technical changes related to waste and feed management that can reduce emissions of this gas.

But achieving deep cuts will require political action.

In countries like Ireland or New Zealand, where agriculture plays a major role in the economy, these changes can be a problem.

For these decisions to be successful, they must be fair and equitable.

“You can’t tell people they can’t raise more cows or sheep anymore,” Professor Thorne says.

“Policies are needed to help transition to other means of land management, but that won’t happen if people say you can’t keep livestock anymore. It has to be a more nuanced approach.”

There is no doubt that consumer choice regarding the meat and dairy diet will have an impact in this sector.

The oil and gas industry also faces a major challenge in reducing methane.

Existing laws fail to stop the leaks. But there is growing interest from companies in the fossil fuel industry in using technology that can quickly identify and eliminate these losses.

“If you look at it from an objective point of view, the industry is improving in spills and accidents, but not fast enough,” says Arnel Santos, a veteran of the oil industry, first with Shell and now with the oil company. .

“We need to move faster to show that we can really deploy technology to improve what we’re doing, 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 scene is the separation of methane from other greenhouse gases.

Because UN climate negotiators deal with 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, similar to the Montreal Protocol, which has successfully brought countries together to regulate the gases that have affected the ozone layer.

“To stop global warming in the long term, we must stop carbon dioxide emissions,” Professor Thorne said.

“But to help us along this path, we can process these gases differently. And if we can process methane differently, we can buy time to adapt to the changes that are occurring.”