Global methane emissions have surged to an 800,000-year high, according to new research from scientists at Stanford University, who warn of dire consequences if the problem is not addressed, SciTechDaily reports.

Methane is one of the most potent of the greenhouse gases (GHGs). While shorter-lived in the atmosphere than carbon dioxide, methane heats the planet nearly 90 times faster over a 20-year period. Its primary sources include agriculture, fossil fuels and waste decomposition in landfills. Despite growing global awareness of the need to tackle methane emissions, annual emissions have increased by 61mn tonnes – roughly 20% – over the past two decades.

Most of this growth has come from coal mining, oil and gas production, cattle and sheep ranching and waste decomposition. “Only the European Union and possibly Australia appear to have decreased methane emissions from human activities over the past two decades,” said Marielle Saunois of the Université Paris-Saclay in France and lead author of the Earth System Science Data paper. “The largest regional increases have come from China and Southeast Asia.”

In 2020, the most recent year for which complete data are available, 65% of global methane emissions – nearly 400mn tonnes – came from human activities. Agriculture and waste alone contributed roughly twice as much methane as the fossil fuel industry.

The research from Stamford tallies with other recent research that says emissions are at an all-time high. The International Energy Agency (IEA) also reported in April that methane emissions are at historic levels, while scientists from the US National Oceanic and Atmospheric Administration (NOAA) reported that all three of the most dangerous GHGs – carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) – are at record levels.

As bne IntelliNews reported, Western governments in particular are ignoring their obligations under the 2015 Paris Agreement to limit their emissions to an agreed carbon budget, designed to keep the rise in global temperatures to within 1.5C of the pre-industrial baseline. Now the global methane budget has also been exhausted, say the Stamford scientists.

The global methane budget is exhausted

“Our best estimates for anthropogenic [human caused] methane emissions in 2020, the last year for which full data for the global methane budget are available, are 372 tonnes [345-409] and 392 tonnes [368-409] global methane budget for bottom up and top down methods respectively,” the scientists said in their paper.

“The largest emissions sources are: wetland and inland freshwaters, agriculture and waste, and fossil fuel production and use. Direct anthropogenic emissions from top-down estimates now comprise ∼65% of global emissions. When the ∼50 per year or more of 'indirect anthropogenic emissions,' such as those from dams and reservoirs, are included, the total is more than two-thirds anthropogenic.”

The Paris Agreement did not set specific methane limits, but it recognised the importance of reducing all GHGs, particularly methane due to its significant impact on short-term warming. The effort was encapsulated in the Global Methane Pledge, launched in 2021, which aims for a 30% reduction in methane emissions by 2030 compared to 2020 levels.

That hasn’t happened. Methane emissions have increased dramatically since 2015, according to the International Energy Agency (IEA).

Global methane emissions have soared, despite a Paris Agreement pledge to reduce them by 30% by 2030

Methane driving the sixth extinction

Rather than reducing the level of emissions, the new research claims that methane emissions continue to surge. The level of methane emissions means the 1.5C limit will be comprehensively missed and puts the world on track for a devastating 3C of warming by the end of the century, according to the members of the Global Carbon Project at Stamford. Other research recently claimed that a quarter of the world’s species or more will die out if temperatures rise by more than 3C due to changes in the ecosystem, in what has been dubbed the world’s man-made sixth extinction event.

Professor Caroline Müller from Germany’s Bielefeld University says: “Studies show that with a rise in global temperatures of 1.5 degrees, the extinction risk of animals and plants increases by 4 per cent – but with a rise of 3 degrees, this risk increases to as much as 26%.”

Around one million animal and plant species are now threatened with extinction, according to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES). The IPCC says a 1.5C average rise may put 20-30% of species at risk of extinction. If the planet warms by more than 2°C, most ecosystems will struggle, according to the World Wildlife Fund (WWF). And the UN has warned that the life-giving biodiversity of the planet is under threat, saying that the world is already experiencing an “unprecedented species extinction rate.”

“Biodiversity forms the web of life that we depend on for so many things – food, water, medicine, a stable climate, economic growth, among others. Over half of global GDP is dependent on nature. More than 1bn people rely on forests for their livelihoods. And land and the ocean absorb more than half of all carbon emissions,” the UN warns. “But nature is in crisis. Up to one million species are threatened with extinction, many within decades. Irreplaceable ecosystems like parts of the Amazon rainforest are turning from carbon sinks into carbon sources due to deforestation. And 85% of wetlands, such as salt marshes and mangrove swamps which absorb large amounts of carbon, have disappeared.”

Reneging on emission pledges

Despite a global pledge by over 150 countries to reduce methane emissions by 30% this decade, emissions have risen at an unprecedented rate over the past five years, threatening international efforts to curb climate change.

“The trend cannot continue if we are to maintain a habitable climate,” write the authors of the study, led by Stanford University scientist Rob Jackson, in Environmental Research Letters. The data, published alongside a paper in Earth System Science Data, shows that atmospheric methane concentrations are now more than 2.6 times higher than pre-industrial levels – the highest they’ve been in at least 800,000 years.

“Right now, the goals of the Global Methane Pledge seem as distant as a desert oasis,” said Jackson, who is the lead author of the paper. “We all hope they aren’t a mirage.”

The COVID-19 pandemic had a complex impact on methane levels. While lockdowns in 2020 reduced emissions of nitrogen oxides (NOx) – a pollutant that can mitigate methane’s atmospheric concentration – this led to a paradoxical rise in methane levels. “The temporary decline in NOx pollution accounts for about half of the increase in atmospheric methane concentrations that year,” Jackson explained. “COVID changed nearly everything – from fossil fuel use to emissions of other gases that alter the lifetime of methane in the atmosphere.”

In 2020, the atmosphere accumulated nearly 42mn tonnes of methane – double the annual average increase seen during the 2010s.

For the first time, scientists from the Global Carbon Project have reassessed methane emissions from natural sources such as wetlands, lakes, rivers and reservoirs. Historically, these emissions were classified as purely natural, but the latest research estimates that human activities have significantly influenced emissions from these sources. For instance, reservoirs built by humans are responsible for approximately 30mn tonnes per year (tpy) of methane emissions, as submerged organic material decays.

“Emissions from reservoirs behind dams are as much a direct human source as methane emissions from a cow or an oil and gas field,” said Jackson. Other human activities, such as fertiliser runoff, wastewater management and land use changes, have also increased methane emissions from wetlands and waterways.

The surge in methane emissions comes at a time when the Climate Crisis is clearly accelerating. As bne IntelliNews reported, the climate models are wrong and have underestimated the rate at which temperatures are rising. Following the hottest summer on record this year, the increases in temperatures are now climbing faster than even in the worst-case scenario of most climate models used by the United Nations’ Intergovernmental Panel on Climate Change (IPCC).

Temperature rises are currently increasing faster than even the worst-case scenario in most climate models

Scientists warn that the world has already reached the threshold of a 1.5°C increase in global temperatures well ahead of the 2030 deadline – a critical limit identified by climate experts to avoid catastrophic consequences.

"The world has reached the threshold of 1.5C increases in global average surface temperature, and is only beginning to experience the full consequences," the researchers noted.

As methane emissions continue to rise, Jackson and his colleagues urge stronger global action to reduce emissions and prevent further warming. With methane’s short lifespan, reductions made today can have a near-immediate impact on global temperatures, offering one of the most effective ways to slow climate change in the coming decades.