Carbon dioxide gases produced by burning fossil fuels are the primary culprits behind climate change, and scientists say they need to be reduced. But there is another gas that must be dealt with: methane. Tackling methane may be the best option for curbing rising temperatures in the short term, according to Rob Jackson, an Earth systems scientist at Stanford University and chair of the Global Carbon Project, which tracks greenhouse gas emissions. “Methane is the strongest lever we have to slow global warming over the next few decades.”
Methane and Its Climate Impact
Methane is considered a short-lived gas in the atmosphere – it lasts for about 12 years, whereas carbon dioxide can last for hundreds of years. Molecule for molecule, methane is much more effective. During the time after its emission, methane can warm the atmosphere more than 80 times more than an equivalent amount of carbon dioxide.
Methane Emission Reduction Strategies
We already have strategies to reduce methane emissions, such as fixing natural gas leaks (where methane is the main component of natural gas), phasing out coal (where methane is released from mining operations), reducing the consumption of meat and dairy (as cows emit a lot of methane), and shifting transportation and appliances to electricity. Research has shown that implementing all existing methane reduction strategies could slow global warming by 30 percent over the next decade.
Challenges of Removing Methane from the Air
However, some climate scientists, including Jackson, say we need to go further. Some sources of methane will be hard, if not impossible, to eliminate. Among these human-caused sources are those produced by rice fields and cattle farms – although there are practices to mitigate these emissions. There are also natural sources expected to release more methane as the world warms. There are signs that tropical wetlands are already releasing more methane into the atmosphere, and rapid warming in the Arctic could turn into a hotspot for microbes that produce methane, releasing a bomb of stored methane from currently frozen soils.
Developing Methods to Remove Methane Directly from the Air
Therefore, scientists want to develop methods to remove methane directly from the air. There are three billion extra tons of methane in the atmosphere today compared to pre-industrial times. Jackson says removing this excess methane could cool the planet by 0.5 degrees Celsius.
Most ideas are still in early research stages. The National Academies of Sciences, Engineering, and Medicine are currently studying these potential technologies, their state of readiness, the potential risks, and what further research and funding are needed. Some approaches include redesigning bacteria that already feed on methane and developing catalytic reactors to place in coal mine openings and other methane-rich areas to chemically convert the gas.
Desiree Plata, a civil and environmental engineer at the Massachusetts Institute of Technology, states that “methane is a sprint, and carbon dioxide is a marathon,” and for scientists interested in removing greenhouse gases, it’s time to race.
Bacteria and Methane Removal from the Air
Methane is easily broken down in the atmosphere where there is plenty of sunlight and highly activated free radicals. But it’s a different story when chemists try to tackle the molecule. The four bonds of methane between carbon and hydrogen are strong and stable. Currently, chemists must expose the gas to very high temperatures and pressures to break it down.
Even obtaining the gas is tricky. Despite its powerful warming influence, it exists in low concentrations in the atmosphere. Only 2 parts per million of air is methane (compared to around 400 parts per million of air being carbon dioxide). So, obtaining enough methane to efficiently store or convert it into something else presents a challenge.
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Living organisms can take methane and convert it even under these modern conditions. These microbial organisms, known as methanotrophs, use enzymes to consume methane. The global natural consumption of methane by methanotrophs living in the soil is about 30 million metric tons annually. Compare that to approximately 350 million tons of methane that human activities injected into the atmosphere in 2022, according to the International Energy Agency.
Microbiologists are eager to learn what
Source: https://www.sciencenews.org/article/methane-capture-air-global-warming-climate
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