2020 Global Methane Budget shows methane emissions heading in the wrong direction with fossil fuel and agriculture sources leading the way

The study was conducted by an international research team and led by the Laboratoire des Sciences du Climat et de l’Environnement (LSCE, CEA-CNRS-UVSQ) in France, under the umbrella of the Global Carbon Project. Two papers related to the study – The Global Methane Budget 2000-2017, and an additional analysis: Increasing anthropogenic methane emissions arise equally from agricultural and fossil fuel sources – were published on July 15, 2020. 

Methane is the second most important anthropogenic greenhouse gas after carbon dioxide (CO₂). Methane is responsible for approximately 40% of the human-caused warming the world has experienced to-date. Since 1750, atmospheric methane concentrations have more than doubled due to emissions from human activities. After a period of stabilization in the early 2000s, methane concentrations started rising again in 2007. 

The study estimates the current growth rate for methane concentrations in the atmosphere to be as high as they were in the 1980’s – 8 to 12 parts per billion each year (ppb/yr). 2017 and 2018 had two of the highest growth rates since 2000 – 8.5 and 10.7 ppb/yr respectively. Combined with CO₂, this level of methane emissions puts the world on a pathway that leads to a 3-4 ˚C increase in mean global surface temperature by 2100, nowhere near the Paris Agreement’s objective to keep warming to well below 2˚C.

The increase in methane emissions is mainly attributed to anthropogenic emissions: 60% from agriculture and waste, and 40% from fossil fuel sources. The main sources identified by the study were:

• 30% from enteric fermentation and manure management
• 22% from oil and gas production and use
• 18% from handling solid and liquid wastes
• 11% from coal extraction
• 8% from rice cultivation
• 8% from biomass and biofuel burning
• The rest is attributed to transport (e.g. road transport) and industry

Tropical regions contributed to approximately 60% of the increase with rest coming from northern mid-latitudes. Methane emissions from the boreal regions did not increase significantly.

The three main regions responsible for increased methane emissions are Africa, China and Asia, and North America. Africa and China and Asia contribute approximately 10-15 million tons of methane each, while North America contributes approximately 5-7 million tons – 4-5 million tons of which originates in the USA.

In Africa and Asia (but not China) the agriculture and waste sector are the main sources of methane emissions, followed by the fossil fuel sector. This is the opposite for China and North America where the increase in the fossil fuel sector is larger than that of the agriculture and waste sectors.

On a more positive note, Europe is the only region where emissions have decreased. The study estimates that methane emissions in Europe decreased by between 4 million and 2 million tons mainly from the agriculture and waste sectors.

Fast action to mitigate methane emissions also offers economic, health and agricultural co-benefits that are highly complementary to CO₂ mitigation. Methane has a lifetime of about 10 years in the atmosphere, much shorter than CO₂. This means actions to reduce emissions can rapidly reduce the rate of warming.

Marielle Saunois, researcher at LSCE-UVSQ and study coordinator, said: “Regular updates of the global methane budget are necessary because reducing methane emissions would have a rapid positive effect on climate. To meet the objectives of Paris Agreement, we need to reduce not only CO₂ emissions but also methane emissions.”

The European Space Agency and the United States’ National Aeronautics and Space Administration (NASA) is working to improve methane monitoring by developing new techniques to make measurements from space, in addition, the private sector is leading several initiatives to develop ‘cubesats’ satellites that measure methane in the atmosphere.

‘Rapid improvements in monitoring methane are on the horizon with aircraft and new satellite missions being developed to target methane point sources, both aiding with mitigation, monitoring, and reducing uncertainties,” said Ben Poulter, NASA Research Scientist.

The Climate and Clean Air Coalition is working to reduce methane emissions through initiatives in the three main emitting sectors: fossil fuels, agriculture and waste.