August 10, 2022
A farmer walks his cattle in the Okavango Delta near the village of Naxaraga, Botswana (Photo: Mineral Bhoyyan / AFP via Getty Images)

Now it is growing fast. But we don’t really understand why. Is it due to increasing use of human energy – gas leaks and coal mining? Or are there new feedbacks, more warming with warming feeding?

Methane is important. According to a report by the new Intergovernmental Panel on Climate Change, global warming, including wider effects, has had a global warming effect of about 0.6 degrees Celsius since 1750. This is about half the effect of carbon dioxide.

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Methane grew strongly in the 1980’s, then stabilized. In 2007, it began to grow again, led by the tropics and sub-tropics, and sometimes to the north, with the strongest growth on record in 2020.

Its new addition threatens the Paris Agreement of the United Nations. Therefore, at the COP26 Climate Summit in Glasgow, more than 100 countries agreed on a global commitment on methane, which requires a 30% reduction in emissions by 2030, in line with the Paris goal of limiting heat to 1.5 degrees Celsius. Could reach

The life of methane in air is about 9.1 years. It comes from both natural sources (about 40%) such as swamps, and human activity (about 60%) from natural gas leaks, most of which is methane.

About 600 million tons are discharged annually. Wetlands release about 200 million tons, cattle 115 million, landfills 70 million, fire 30 million. The gas, coal and oil industries produce about 120 million tons of fossil fuels annually.

Rotting vegetables in wetlands and belly bogs produce methane in tropical regions – especially the Amazon, Nile and Congo basins – and in Siberia and Canada, where beavers have excellent methane machines, wetlands and cut plants Recruits from

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The stomachs of rumors such as cows, sheep and deer are microbiologically similar to wetlands, so these animals breathe methane. Other biologically, or ‘biogenic’ sources include landfill, sewerage, and leaky bio digester facilities. ‘Pyrogenic’ sources are crop waste, meadows and forest fires, mostly human light.

An indication of why methane has been rising since 2007 is found in carbon ‘isotopes’. Carbon has two non-radioactive, stable forms, or isotopes, carbon-12 and carbon-13, and radioactive carbon-14, which archaeologists use for dating.

Different methane sources have stable isotopic ‘signature’ properties, carbon-12 and carbon-13 ratios. Methane from fossil fuels and fire is slightly higher in carbon-13, while biogenic methane is slightly lower.

The Ice Corps shows that for two centuries up to 2007, carbon dioxide in methane was increasing in the atmosphere, driven by fossil fuel emissions. But since 2007, when the rise of methane renewed, the isotopic phenomenon has reversed, now moving towards carbon 12.

This suggests that biologically generated emissions – not fossil fuels – have been driving recent developments since 2007.

Why are biological emissions from wetlands and agriculture increasing, especially in the tropics where growth has been fastest, and also in the north?

Wetland emissions increase with increasing temperature. Rainfall has also recently increased in key parts of the humid tropics, increasing in both wetlands and supporting more grass and more cows, sheep and goats. So can methane feedbacks work, there is more heat than feeding heat?

Scottish scientists are the leaders here. In the MOYA consortium of the UK Natural Environment Research Council, Carol Halfter and Ute Skiba, along with the UK Center for Ecology and Hydrology in Penicuik, Mangaliso Gondwe of Botswana, are measuring emissions from the Okavango swamp. At the University of Edinburgh, Paul Palmer and Mark Lint have used satellites to see Africa at large. In Aberdeen, Pat Smith and Joe Smith are leaders in understanding the global food system.

MOYA teams are flying low-altitude aircraft to measure wetlands, farm and fire emissions and isotopic signatures in Senegal, Uganda, Zambia, Bolivia, and Arctic Scandinavia, with large summer emissions from wet Siberian wetlands. Tracking

They found some huge emissions. In Zambia, the Bingovolo Wetlands (where Dr. Leungstone died) may be half as much methane as the United Kingdom and the Bolivi
an Amazon may be more. We do not yet know if biogenic emissions are increasing due to the effects of climate warming, but it seems so.

The obvious answer is to reduce human fossil fuel emissions. Gas leaks are easy to find but long-term cuts require reduced use, especially long-distance gas pumping or liquefied natural gas emissions that emit both methane and carbon dioxide.

Hydrogen is an alternative, but it is a leak, an indirect greenhouse gas, which causes air pollution and affects ozone. ‘Non-greenhouse’ electricity can be better than home heating and solar energy (preferably on warehouse roofs, not on arable land).

Coal-mining countries such as China, India, South Africa, Russia and Australia will be affected by climate change, but they have not signed the global methane treaty. Methane can be extracted from coal mines. It is necessary to completely eliminate the use of coal but political ammunition. Coal means jobs, because of it, despite air pollution. There is still smoke in Scotland over Thatcher’s closure. The debate is now in South Africa, which is bravely trying to create new jobs in renewable sources.

It is difficult to reduce farming emissions. It may be possible to remove methane around dairy warehouses. But in many tropical countries, cattle are an important source of food and culturally important. India has the largest number of cows so far, while pastures feed Africa’s growing human population. Abandonment of livestock will accelerate farming and fertilizer use, with increased emissions and deforestation.

However, much can be done. Extensive crop waste fires emit methane and cause air pollution. It is possible to reduce irritation. Exhaust from tropical landfills can be cut with a thin clay cover. In Africa, rising agricultural emissions reflect the demands of a rapidly growing population and growing obesity. Women’s education, social support, and good governance strengthen them all.

Is Methane an Emergency? Yes. But the global methane era can be successful, with determination and strong community support, in tropical countries as well as in developed countries.

Professor Euan Nisbet led the UK MOYA ‘Global Methane Budget’ consortium. His lab at the University of Royal Holloway, London, is funded by the NERC, the European Commission and the United Nations Environment Program.

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