Methane levels are surging. Enforceable policies for emission reductions are essential.

Key messages

• Atmospheric methane levels have grown substantially since 2006, mainly due to rising emissions from human sources. Growing emissions of methane from fossil fuels, livestock and waste are the main drivers, followed by more variable natural sources. 
• Cuts to emissions from fossil fuels and waste management industries are most feasible to mitigate rising methane levels. The agricultural sector, although harder to reform, also has significant reduction potential.
• There has also been a growth in natural methane emissions due to climate-driven feedbacks. Without rapid action to curb greenhouse gas emissions from human sources, these natural sources of methane – such as wetlands – are likely to continue to grow, requiring greater reductions from human activities.
• We have enough information about methane emissions to take action, but enforceable policies to drive reductions are vital.

It may be short-lived but methane is a potent greenhouse gas, with rising emissions of methane accounting for an increase of 0.5°C in average global temperatures since the late 1800s. Following a plateau in the early 2000s, atmospheric methane levels have resumed growth since 2006, with the last five years seeing the fastest rise ever since records began. Rapid and deep cuts in methane emissions from human activities are vital, alongside efforts to curb carbon dioxide emissions, in order to limit warming within the Paris Agreement goals. 

Understanding the main factors behind the recent rise in methane levels is crucial for developing an adequate mitigation strategy. Evidence points to increasing emissions from human activities, likely from livestock and waste emissions followed by fossil fuel production and use as primary contributors, as well as reductions in methane’s atmospheric removal and a rise in emissions from tropical wetlands. In the decade from 2010, methane from human sources accounted for around two-thirds of total methane emissions. There are still large uncertainties about those sources, with different models and monitoring efforts providing different results, though estimates for categories of sources and sinks generally coincide. Satellite capabilities have improved understanding of methane sources over large areas and can detect large emissions from individual industrial facilities, such as coal mines, oil and gas production facilities, and gas pipelines. Alongside modelling efforts and expanded air sampling for methane isotope analysis, this helps to provide a clearer picture of emissions from various sources, including landfills, rice paddies and livestock, allowing for better designs and strategies to reduce methane emissions. 

Deep cuts to methane emissions from fossil fuel and waste management industries are the most feasible, and many solutions are cost-effective as well, since they improve efficiencies and use existing technologies. In the fossil fuel sector, a relatively small number of large, intermittent sources have an outsized impact on total emissions. Clusters of large emissions from oil and gas facilities and gas pipelines, as well as coal mining, have been observed around the world, including published detected methane plumes in Algeria, China, Kazakhstan, Russia, Turkmenistan and the US, often exhibiting emissions of tens of tonnes an hour. Persistent emissions have also been detected from urban solid waste facilities around the world, for example in Buenos Aires, Delhi, Lahore and Mumbai, with emissions in the range of 3 to 29 tonnes per hour. The agricultural sector is the largest methane source from human activities (Figure 1) and is tougher to tackle, though there are options. Mitigations include the use of lower-emitting livestock feeds, manure management, diet changes away from farmed meat, and reduction in food waste. While technologies are emerging for methane removal, or to oxidise it to CO2, these are in the early stages and would require significant development, scaling and incentivisation to be cost-effective. 

Looking at emissions from natural systems, a global rise of 4–6% from the 2000s to the 2010s is estimated from multiple lines of evidence, with increases particularly from tropical wetlands. Temperate and Arctic regions may also be experiencing increases, but there is not yet sufficient evidence to determine trends. Natural sources of methane are hard to control, so if they continue to grow, deeper cuts to greenhouse gas emissions from human sources will be needed. Globally, climate feedback mechanisms are expected to further amplify emissions from natural systems, yet many Earth system and integrated assessment models do not yet include these feedbacks, or have significant uncertainties in how they represent methane sources. This could mean that their future emissions in a warming world are underestimated, a risk that should be accounted for in comprehensive mitigation scenarios. 

We have enough information about the sources of methane, and sufficient monitoring capacity, to take action quickly and effectively. Methane emissions reductions are tractable and have been demonstrated, but with only 13% of methane emissions currently covered by mitigation policies, stronger and more consistent action is needed to reverse the trend in atmospheric methane. The Global Methane Pledge (GMP), signed by 158 country participants, has a clear target of a 30% reduction in methane emissions from 2020 levels by 2030. This voluntary initiative has pushed the institutionalisation of methane reporting forward, but progress on implementation is urgently needed for fulfilling the GMP target and the Paris Agreement goals.