Despite general efforts to curb emissions, the volume of human-caused methane emissions has risen by 20% over the past two decades. Global methane emissions are climbing rapidly and reaching record highs, threatening climate targets, and they are largely driven by human activity.
The study Global Methane Budget 2024, published in the journal Earth System Science Data, provides a wide-ranging analysis of methane emission trends and their impact on climate change. It was prepared by an international consortium of scientists, the Global Carbon Project. The report concludes that human activity is today responsible for at least two thirds of global methane emissions. Despite general efforts to curb emissions, the new calculations show that the volume of human-caused methane emissions has grown by 20% over the past two decades.
The concentration of the gas in the atmosphere reached “1,923 parts per billion” in 2023. That is 2.6 times higher than in the pre-industrial period and the highest concentration in at least 800,000 years. This trend “cannot continue if we want to preserve a climate fit to live in”, the researchers stress in a separate article published alongside the report. The scientists conclude that the current emissions trajectory would put at risk the 1.5 °C limit on global warming set out in the Paris Agreement.
Why are methane emissions a problem?
Methane is a very powerful greenhouse gas that remains in the atmosphere only for a short time. It comes from natural sources such as wetlands, or from human-caused (anthropogenic) sources such as agriculture and the fossil fuel industry. In the first 20 years after release, this gas warms the atmosphere almost 90 times faster than carbon dioxide.
Tackling methane emissions is crucial to meeting climate targets, because there is currently no technology capable of removing this gas directly from the atmosphere.
Where do human-caused methane emissions come from?
The world's five largest methane emitters are China (16%), India (9%), the USA (7%), Brazil (6%) and Russia (5%).
The report finds that agriculture, including livestock farming and rice paddies, remains the largest source, accounting for 40% of global anthropogenic methane emissions. Fossil fuel use accounts for 34%, waste management for 19% and biomass burning for 7%.
Emissions in these sectors have grown because of increased activity in developing regions and more intensive fossil fuel use. However, the researchers made important changes in their latest assessment of methane sources. Previously they had classified all emissions from wetlands, lakes, ponds and rivers as natural. The latest edition of the report attempts to quantify the influence of human activity on the rising emissions from these sources. For example, human-built reservoirs release roughly 30 million tonnes of methane a year, because organic matter gives off methane as it decomposes.
Scientists estimate that about a third of methane emissions from wetlands and fresh water in recent years have been influenced by human-driven factors, including reservoirs and emissions increased by fertiliser run-off, waste water, land use and rising temperatures.
Is the world on track to meet its methane reduction targets?
There are significant international commitments to cut methane emissions, among them the Global Methane Pledge signed by 150 countries, which aims to reduce methane emissions by 30% by 2030.
According to Stanford University scientist Rob Jackson (Rob Jackson), who leads the Global Carbon Project (Global Carbon Project), the goals of this pledge now “seem as distant as an oasis in the desert”.
Researchers at the Global Carbon Project found little evidence that the world is making progress on the commitment to cut methane emissions.
Satellite data show that methane emissions rose by a further 5 per cent between 2020 and 2023. The largest increases were seen in China, South Asia and the Middle East. Emissions from coal mining in China and from oil and gas extraction in the Middle East were the main sources.
“Only in the European Union and possibly Australia have human-caused methane emissions fallen over the past two decades,” stresses Marielle Saunois (Marielle Saunois) of the University of Paris-Saclay in France, lead author of the Earth System Science Data paper.
If current trends continue, the report warns, we are unlikely to meet the targets set by the Global Methane Pledge. The observed rise in emissions matches the most pessimistic greenhouse gas emission scenarios of the Intergovernmental Panel on Climate Change. That could mean global temperatures rising by more than 3 °C above pre-industrial levels by the end of the century.