Methane: Is reducing the gas easiest way to cool Earth?

Methane is an extremely powerful greenhouse gas responsible for about 30 per cent of global warming. Carbon dioxide stays in the atmosphere for hundreds of years. But methane breaks down quickly. This means cutting methane emissions could rapidly reduce the rate of warming in short time.

People can reduce methane gas emitted from their activities by 45 per cent in 10 years. Such reductions would avoid nearly 0.3 degrees Celsius of global warming by 2045.

It is the first time an investigation has looked into the role of methane in climate and air pollution.

Methane is one of gasses which trap heat in the atmosphere causing global warming. In addition, methane is a dangerous air pollutant.

Benefits of cutting methane

Global Methane Assessment by United Nations Environmental Programme shows that reducing methane would reduce deaths, heat and crop losses.

A 45 per cent methane reduction would prevent 260,000 premature deaths and 775,000 asthma-related hospital visits every year.

In addition, this would save 73 billion hours of work lost due to extreme heat. Further, it would save 25 million tonnes of crop losses annually.

UNEP Executive Director Inger Andersen said cutting methane is the strongest lever to slow climate change. This would complement efforts to reduce carbon dioxide, she added.

If people could reduce methane emissions by 45 per cent it would avoid nearly 0.3C of global warming by 2045. This would bring Paris Climate Agreement’s goal to limit global temperature rise to 1.5C within reach, the report says.

UNEP released the Global Methane Assessment on 6 May 2021. UNEP worked with Climate and Clean Air Coalition, an international partnership working to protect the climate.

Where does methane emissions come from?

The report says that most methane emissions caused by humans come from fossil fuels, waste and agriculture.

Fossil fuels are primarily coal, fuel oil or natural gas, formed from the remains of dead plants and animals.

Extracting, processing and distributing fossil fuels account for 23 per cent of methane emission. Coal mining accounts for 12 per cent of the emissions.

China is the largest emitter of methane from coal mining. Middle East, Russia, United States and Canada are the leading emitters of methane. This is mainly from oil and gas extraction, processing and transport.

Sites designated for dumping garbage (known as landfills) and wastewater make up about 20 per cent of emissions. Countries account for almost equal amount of methane emissions from waste.

Methane emissions from manure and fermentation that takes place in the digestive systems of animals represent about 32 per cent. Ruminants such as cattle, sheep, goats and camels use their forestomach to ferment their food to make it digestible.  

South America followed by South Asia give the highest livestock emissions.

Rice farming accounts for 8 per cent of methane emissions. Methane emissions from rice farming are highest in South East Asia, South Korea, Japan, South Asia and China.

How can we cut methane emissions?

UNEP Executive Director Inger Andersen said readily available measures could cut 30 per cent methane emissions in 10 years. Most of these technical solutions are in oil, gas and coal, and waste sectors, she said.

The targeted measures to reduce methane emissions are majority at negative or low cost, Global Methane Assessment says.

Most of the measures to reduce methane emissions are fossil fuel. It is relatively easy for firms to locate and fix methane leaks and reduce venting, the report says.

In addition, the report gives targeted measures that waste and agriculture sector must take.

There should be no landfill of organic waste, the report says. People must separate household solid waste at home for recycling or reuse. They should not dump organic waste in landfills.

Authorities must treat waste in landfills and recover energy. They should recycle or treat industrial solid waste so as to recover energy.

The report proposes upgrading of residential wastewater to a higher treatment method so as to recover and use biogas. Also, it supports building of wastewater treatment plants instead of latrines. 

The report urges people to change the way they handle livestock manure. It recommends treatment of manure in biogas digesters. In addition, it suggests decreased manure storage time and improved manure storage covering.

On rice farming, the report encourages improved water management or alternate flooding and drainage wetland rice. Decomposing organic material in flooded rice fields produce methane. 

The report urges authorities to prevent burning of agricultural crop remains. It proposes to governments to enforce or introduce laws prohibiting burning of agricultural waste.