Let a molecule of
carbon dioxide escape into the atmosphere, and it stays for centuries.
There’s more than enough up there to smother the planet like a
too-warm quilt, trapping heat within and weirding the weather. The
damage will be felt for generations.
But CO2 is
only part of the patchwork of warming. Methane locks in far more heat
in the short term and has been leaking just as relentlessly.
Absolute Global Warming Potential (AGWP) is a model that describes
heat trapped by a kilogram of gas over time. This radiative forcing is
measured in watts per square meter per kilogram per year, and is
represented here in picowatts. Global Warming Potential (GWP) is the
ratio of the AGWP of methane and of CO2.
Sources: Environmental Defense Fund; Intergovernmental Panel on
That’s why the U.S.
and the European Union have been pressing countries to make a
methane-cutting pledge. If enough nations sign up and meet the
target—reaching a 30% reduction from last year’s levels by the end of
the decade—the global movement against methane could prove to be one
of the crucial achievements of the COP26 climate talks taking place in
November in Glasgow, Scotland.
But much more could be
done. Raising that target to 50% could help us prevent 0.3°C of
warming by the 2040s and 0.5°C by 2100, according to the
Intergovernmental Panel on Climate Change. Given that the planet has
already heated up 1.1°C, it would make a big difference to the world’s
long-term warming forecast. Move quickly enough on methane, and the
Paris Agreement goal of limiting the temperature increase to 1.5°C
becomes far more feasible.
“The conversation is
changing. Methane has risen to the fore,” says Sarah Smith, program
director for super pollutants at Clean Air Task Force, a nonprofit
advocacy group. “World leaders are starting to recognize that curbing
methane is the only clear strategy to cut warming over the next two
Methane vs. Carbon Dioxide
An atmospheric census
would find 200 molecules of CO2 for every one of methane.
Yet methane has caused nearly
a quarter of the world’s observed heating over the past two and a
half centuries, while CO2 accounts for only about half.
The difference comes
down to atmospheric physics and molecular mechanics. Every day the sun
pumps vast amounts of energy into the planet. Some of it is absorbed
by the land and oceans at the Earth’s surface, but most is reflected
back into the sky in the form of infrared radiation. It’s on that
journey back into space that most of the heat gets trapped under the
quilt of greenhouse gases. The CO2 molecules number an
astonishing 30 trillion trillion trillion trillion—that’s 30 followed
by 36 zeros—all jiggling constantly while absorbing and reflecting
Methane does the same,
except that its molecular structure, consisting of a carbon atom
surrounded by four hydrogen atoms, traps heat more effectively. But
that molecular structure and elemental makeup also allows methane to
break down faster. This process happens through its easy interaction
with other gases, such as oxygen, through which it forms new
compounds, including CO2.
most of the methane released by direct human action has come from rice
production and raising cows, which belch the greenhouse gas in
significant quantities. But over the past 50 years, leaky fossil fuel
infrastructure, much of it tied to the rise of natural gas, has also
grown to become a supersized contributor.
The good news is
that we have the tools we need right now to stop a large chunk of
those emissions. Research by the United Nations found that as much
80% of measures to curb leaks from oil and gas operations can be
implemented at no cost, and many may even result in
savings. Virtually all methane leaks from the coal sector could be
“A huge amount of methane leakage is
happening in the oil and gas industry,” says Cat Abreu, founder and
executive director of Destination Zero, which seeks to eliminate
fugitive methane. “It’s very cheap to cut, and, in many cases, it’s a
Cutting Here Tools already exist to eliminate 58% of
global methane emissions by 2030
Technically and economically feasible
- Technically feasible -
Even though lost methane is a product that
companies can sell to heat homes and spin power-plant turbines, most
put little effort into tracking down fugitive plumes. Efforts by the
U.S. government to monitor leaks since 2014 haven’t nearly reflected
the full scope of the climate damage.
Using satellite data, researchers from Harvard found
that emissions from the Permian Basin in Texas and New Mexico over an
11-month period were twice government figures. Emissions in the state
of Pennsylvania are at least 15% higher than previously thought,
a study by
scientists at Cornell.
satellite-analytics company Kayrros SAS estimates that the Permian
basin has emitted more than 2 million tons of methane this year
through September, equivalent to the annual emissions from at least
40 million passenger cars.
Until recently methane detection was more of
a craft project than a science. Producers and regulators relied on
crude techniques such as throwing a tarp over a pipe to see if it
bubbled or sending workers out to inspect equipment. There are now a
host of technologies to detect fugitive methane, from parsing
satellite data to deploying drones and handheld infrared cameras. Once
a leak is detected, plugging it isn’t that different from high-tech
Regulations in many
countries also require coal-mining companies to build infrastructure
that recovers methane before it’s released. The gas is collected and
burned to help power the plant’s operations, so the costs work out
favorably in the end.
The trash piled up in
the landfills doesn’t just release CO2 when it decomposes.
In the absence of oxygen, methane forms instead. The gas builds up
inside the mountains of waste, eventually escaping to the surface.
Large clouds of methane in cities from Buenos Aires to
Lahore have been attributed to landfills.
“Landfills are pretty complicated
facilities,” says Bram Maasakkers, a researcher at the Netherlands
Institute for Space Research. Scientists estimate that about 10% of
human-caused methane comes from landfills, he says, “but how good the
data is varies across the world.”
A growing number of
landfill operators are starting to capture methane at their sites,
which can be used to fuel the plants and garbage trucks. The
Environmental Research Letters study estimates that 80% of
emissions from landfills could be mitigated by 2030 using existing
technology. The other solution is to cut down on waste and recycle
more trash instead of discarding it.
The largest source of
methane comes from growing the crops and meat that feed the world. And
those emissions are set to grow as the global population increases and
developing countries get richer.
More than two-thirds of the world’s rice is
grown by flooding fields that cover an area twice as large as France.
Microbes in the waterlogged soil produce large quantities of methane.
Research in China, one
of the biggest producers of rice, has found it’s possible to cut
half by draining water from rice paddies in the middle of the
growing season. The process also increases rice yields and saves
water. Other researchers, in India and the Philippines, have found new
varieties of rice that can thrive in dry fields—though their
yields don’t yet match those of widely grown varieties.
For the world’s 1.4
billion cows, the problem starts in the gut. The ruminants get
help from bacteria to break down the hard-to-digest grasses they eat.
The cost, however, is the production of methane as a byproduct.
Cutting these methane emissions is more
challenging, but researchers are working on several potential
solutions. One is to use special feed
additives that help cows produce less methane. Cargill, the
world’s largest agriculture company, is also urging suppliers to put
masks on cattle that would trap methane and convert it into CO2.
A dairy cow in Hertfordshire, England, wears
a methane-reducing mask developed by Zelp Ltd.
Photographer: Hollie Adams/Bloomberg
In the fight against
global warming, methane has flown under the radar for too long. But
there’s increasing recognition that tackling the invisible, odorless
gas is one of the easiest, cheapest, and most feasible ways to make
a real difference in slowing climate change. It’s the rare climate
problem with a fix that can be felt by those alive right now, not
“The world will
continue to warm as long as CO2 is being pumped into the
atmosphere,” concluded an August editorial in the scientific journal
Nature. But curbing methane will help buy “humanity a bit more time
to do what needs to be done.”