COP28: How big a problem are methane and other non-CO2 greenhouse gases?

Carbon dioxide just isn’t the one greenhouse gasoline underneath hearth on the COP28 local weather summit in Dubai, United Arab Emirates. On 2 December, the UAE, the US and China are convening different international locations for a gathering centered on methane and different “non-CO2” greenhouse gases, with bulletins anticipated from the fossil gasoline trade on chopping these emissions.

When it comes to contribution to local weather change, methane is essentially the most vital of those. However different gases, resembling nitrous oxide and fluorinated gases made for refrigeration, are additionally of concern.

How a lot of an issue are non-CO2 greenhouse gases?

Collectively, they’re accountable for round a 3rd of human-caused warming to this point, and the Paris settlement local weather targets received’t be reached with out slashing these emissions together with CO2, says Mathijs Harmsen at Utrecht College within the Netherlands. “It doesn’t get the eye in keeping with the climatic influence it has.”

However there may be renewed focus at COP28. “We see COP28 as a turning level” for limiting the emissions of those short-lived non-CO2 greenhouse gases, says Martina Otto, who heads the Local weather and Clear Air Coalition on the UN.

What are the principle non-CO2 greenhouse gases?

Methane is the non-CO2 greenhouse gasoline that has had the best impact on local weather change. It’s adopted by nitrous oxide and manufactured fluorinated gases, or “F-gases”, that are emitted in comparatively small quantities however are much more potent than CO2. Sulphur hexafluoride, as an example, which is used as {an electrical} insulator, has a warming impact extra than 23,000 times that of CO2, gram for gram.

Methane has each pure and human-caused sources – nearly all of the latter come from fossil gasoline manufacturing, attributable to leaks from wells, coal mines, pipelines and ships. Burping cows and different livestock make up the second largest share, adopted by landfills, which launch methane as food and other organic matter decomposes. Warming temperatures additionally increase methane emissions from natural sources like wetlands and thawing permafrost. These many sources have made it difficult for researchers to zero in on precisely what has been driving a steady rise in emissions since 2007.

Nitrous oxide additionally has pure sources, resembling wetlands. However human-caused emissions of the gasoline have risen since the industrial revolution, primarily as a result of growing use of nitrogen fertilisers and livestock manure.

F-gases have been manufactured for refrigeration and different functions because the early twentieth century. Chlorofluorocarbons (CFCs) have been extensively used as a refrigerant till international locations agreed within the 1987 Montreal Protocol to section out their use attributable to their degrading impact on the ozone. This phase-out is expected to avoid as much as 0.5°C of warming this century, though CFCs are nonetheless illegally being produced in some international locations. The most typical substitute for CFCs, hydrofluorocarbons (HFCs), don’t degrade the ozone, however have a warming impact that’s tons of or 1000’s of occasions stronger than CO2. In 2016, countries agreed to amend the Montreal Protocol to start phasing out HFC’s as nicely.

Which of those non-CO2 gases is the largest concern?

Methane is accountable for practically the entire warming attributable to non-CO2 gases to this point, or a couple of quarter of total warming. “It’s actually a methane story,” says Harmsen.

Methane sticks round within the environment for less than round 12 years, whereas CO2 can stay for millennia, however the gasoline is round 30 occasions stronger than CO2. Whereas long-lasting CO2 emissions more and more dominate over time, coping with methane and different non-CO2 gases has a major near-term impact. Harmsen and his colleagues lately found that conserving international warming inside Paris settlement limits could be unimaginable with out steep reductions in these non-CO2 gases.

“You will want to go fairly deep with chopping non-CO2 to consider reaching the Paris settlement targets,” says Harmsen.

What are international locations doing to scale back non-CO2 greenhouse gasoline emissions?

On the COP26 local weather summit in Glasgow in 2021, the US and the European Union launched the International Methane Pledge, the place countries promised to cut the world’s methane emissions by 30 per cent by 2030. Since then, greater than 150 international locations have joined the pledge. Approaches to stemming the tide embrace plugging leaks or stopping releases from fossil gasoline manufacturing and capturing emissions from landfills, amongst many others.

Nitrous oxide emissions may very well be diminished by using fertiliser more efficiently and by adopting extra sustainable modes of agriculture, as an example. And due to the Montreal Protocol, the F-gases are already being replaced with less harmful alternatives.

What is occurring at COP28 now round non-CO2 gases?

Methane is a significant focus at COP28 in Dubai. “What we see right here is an evolution and sharpening of what began in Glasgow,” says Matt Watson on the Environmental Protection Fund, an environmental advocacy organisation within the US. “The businesses producing emissions are being requested to step to the road and make company-specific, significant targets.”

A joint statement by the US and China forward of the assembly committing to incorporate particular targets on methane and different non-CO2 greenhouse gases has additionally raised hopes for a powerful end result at COP28.

In his opening tackle to the summit, COP president Sultan Ahmed Al Jaber known as on international locations to undertake net-zero methane targets. He additionally hinted at pledges on decreasing methane from oil and gasoline corporations anticipated on the summit. Although he didn’t identify particular companies, he says these will embrace pledges from the nationally owned oil and gasoline corporations accountable for almost all of emissions. “Zeroing out methane emissions would make a huge effect within the shortest timeframe,” he stated.