Rising methane emissions threaten Earth's habitability

Global methane emissions have continued to rise at an alarming rate despite international efforts to curb them. 

More than 150 countries have pledged to reduce methane emissions by 30% by the end of this decade, yet new research reveals that in the past five years, methane emissions have surged faster than ever before.

In a perspective article published on September 10 in Environmental Research Letters, alongside data in Earth System Science Data, researchers warned that the current trend “cannot continue if we are to maintain a habitable climate.” 

Both papers were part of the Global Carbon Project, led by Stanford University scientist Rob Jackson, which tracks global greenhouse gas emissions.

Extreme trajectory of rising methane rates 

The data reveals that atmospheric methane levels are now more than 2.6 times higher than pre-industrial levels, marking the highest concentration in at least 800,000 years. 

Methane emission rates are currently rising along the most extreme trajectory predicted by climate scientists. This trend could lead to global warming of more than 3 degrees Celsius (5 degrees Fahrenheit) by the end of the century. 

“Right now, the goals of the Global Methane Pledge seem as distant as a desert oasis,” said Jackson, who is the Michelle and Kevin Douglas Provostial Professor at Stanford’s Doerr School of Sustainability. “We all hope they aren’t a mirage.”

Spike in methane emission rates

Methane, though short-lived compared to carbon dioxide, is a potent greenhouse gas. During its first 20 years in the atmosphere, methane traps heat nearly 90 times more effectively than carbon dioxide, making it a critical target in efforts to limit global warming. 

However, despite increased attention on methane reduction, total emissions have surged by 61 million tons – or about 20% – over the past two decades. 

This spike has been primarily driven by increases in coal mining, oil and gas production, livestock farming, and decomposing organic waste in landfills.

Regional disparities in methane emissions 

Marielle Saunois of Université Paris-Saclay, lead author of the Earth System Science Data paper, emphasized the regional disparities in methane emissions.

“Only the European Union and possibly Australia appear to have decreased methane emissions from human activities over the past two decades. The largest regional increases have come from China and southeast Asia.” 

Methane from human activities 

In 2020, the most recent year for complete data, around 400 million tons – or 65% – of global methane emissions were linked to human activities. 

Agriculture and waste management together contributed two-thirds of these emissions, while the fossil fuel industry was responsible for the remainder. The researchers found that methane emissions from human sources have continued to rise through at least 2023.

Reduced emissions of nitrogen oxides

A particularly sharp increase in atmospheric methane was recorded in 2020, with 42 million tons added – double the average annual increase during the 2010s and more than six times the increase seen during the early 2000s. 

Pandemic lockdowns in 2020 temporarily reduced emissions of nitrogen oxides (NOx), pollutants that typically degrade methane in the atmosphere. This reduction in NOx emissions contributed to the methane buildup. 

“We’re still trying to understand the full effects of COVID lockdowns on the global methane budget,” Jackson explained. “COVID changed nearly everything – from fossil fuel use to emissions of other gasses that alter the lifetime of methane in the atmosphere.”

Growing influence of humans on methane rates

In their most recent assessment, Global Carbon Project scientists revised how they classify methane sources. 

Previously, all methane from wetlands, lakes, and rivers was considered natural. However, the latest methane budget accounts for the growing influence of human activities on these emissions. 

For example, human-made reservoirs contribute an estimated 30 million tons of methane annually, as submerged organic material decays and releases the gas. 

“Emissions from reservoirs behind dams are as much a direct human source as methane emissions from a cow or an oil and gas field,” noted Jackson.

Threat to global climate goals 

The researchers estimate that about one-third of methane emissions from wetlands and freshwater sources in recent years have been influenced by human factors, such as agricultural runoff, wastewater, land use changes, and rising temperatures.

The continued rise in methane emissions poses a significant threat to global climate goals. As extreme weather events and heat waves become more frequent, the consequences of this trend are becoming increasingly clear. 

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

Urgent action is needed

Addressing this challenge will require global efforts to reduce methane emissions at their source. This includes implementing measures such as leak detection in the fossil fuel industry, improved waste management, and changes in livestock farming practices. 

Without urgent and concerted action, methane emissions will continue to drive global temperatures beyond critical thresholds, threatening the planet’s habitability.

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