Satellites can now find the sources of methane leaks. The tech will reshape global climate accountability.

• Satellites can locate the sources of methane plumes, the second-largest climate pollutant.  
• Remote sensing and AI make it possible to identify and fix methane leaks faster.
• The satellite technology is ushering in a new era of climate accountability.

Over five years, California's largest natural-gas utility received a handful of critical alerts about methane escaping from its infrastructure. The leaks might have gone undetected for much longer.

The warnings to Southern California Gas Company came from state regulators, who between 2016 and 2021 worked with NASA to identify large methane plumes from the oil-and-gas, agriculture, and waste industries using airplanes carrying high-resolution remote sensors.

Within days, Southern California Gas Company confirmed the leaks and fixed the pipelines. The utility also replaced a valve at a compressor station within a few months, limiting the amount of damaging methane that entered the atmosphere. 

By the end of next year, the remote sensors will hitch a ride into space on two satellites as part of a new era of global-climate accountability. Satellites can now pinpoint and quantify methane leaks almost anywhere and, within days, computers can calculate the amount of emissions escaping with artificial intelligence.

This allows companies to fix leaks faster and — just as importantly — exposes countries and companies that scientists suspect underreport their emissions. 

Curbing methane is one of the quickest ways to slow global warming, because while it has 80 times the warming power of carbon dioxide, methane only lasts in the atmosphere for about a decade. Carbon dioxide endures for centuries.

But detecting potent methane is much more challenging. Leaks are unpredictable and finding them still typically involves expensive field studies with aircraft and handheld infrared cameras that make the colorless gas visible. That approach only offers a snapshot in time.

"In the last decade, satellites have mainly been used to quantify emissions at a large scale. That's important, but the other key is timely, actionable data so operators can find and fix leaks and verify that they stay fixed. That's a huge change," Riley Duren, the CEO of Carbon Mapper — which is managing the launch — said.

The nonprofit is an outgrowth of the California Methane Survey, which Duren initiated while at NASA's Jet Propulsion Laboratory in La Cañada Flintridge, California. The research project recently announced it prevented 48,000 metric tons of methane from entering the atmosphere from oil, gas, landfills and manure pits — the equivalent of taking nearly 260,000 cars off the road. That figure could more than double once more follow-up flights verify actions companies have taken. 

For its part, SoCalGas said it had reduced so-called fugitive-methane emissions by 37% since 2015, mainly due to  more frequent aerial and ground-based monitoring and a steep decline in venting gas during maintenance and repairs.

Deanna Haines, the environmental-sustainability and planning senior manager for SoCalGas, said airplanes map about two-thirds of the utility's 100,000 miles of pipeline over the course of a year. A satellite, however, can catch leaks that happen between those surveys. 

"A satellite can take three, four snapshots a day so you're going to find things much quicker and have more confidence in the data," Haines said, adding that SoCalGas will continue to work with Carbon Mapper once the nonprofit launches its satellites. "Any extra set of eyes and helping identify larger leaks is really important."

This plan offers a glimpse into the potential of Carbon Mapper once fully deployed. The company isn't alone. The Canadian emissions-monitoring company GHGSat, as of May, had six satellites the size of microwaves orbiting the Earth, with four more planned by the end of 2023. Oil majors such as Shell, Chevron, and TotalEnergies have hired GHGSat to reduce leaks and research methane emissions at sea, where nearly 30% of oil and gas production takes place. In recent years, GHGSat has also identified "super-emitter" events and notified operators, most recently from the largest coal mine in Russia. 

The Environmental Defense Fund will also launch its own satellite next year. MethaneSAT will capture broader regions that account for more than 80% of the world's oil and gas production. It is an extension of the nonprofit's years-long research project that found methane emissions from the US natural-gas supply chain were 60% higher than government estimates. 

Mark Brownstein, the EDF's senior vice president of energy, said MethaneSAT can detect more diffused sources of the gas that satellites such as those from the European Space Agency might miss. A computer program can automatically analyze the data in a matter of days instead of months.

Scientists have already been using data from satellites to identify and measure methane leaks and reveal that the problem is more widespread than they had previously thought, but the research can take a long time. 

"Timely data is important," Brownstein said. "The idea is to inform in a way that leads to action."  

Brownstein added that MethaneSAT and the growing constellation of satellites are akin to a photographer with different camera lenses. Combined, they can help track how countries and companies are performing on goals to reduce emissions.  

More than 100 countries signed the Global Methane Pledge last year during the United Nations' Climate Change Conference. Signatories agreed to cut methane emissions by 30% by the end of the decade, though some of the biggest emitters including China, India, and Russia have yet to sign. 

The UN is aggregating methane emissions from satellites and other sources into a global database, starting with the energy industry, making it possible to track who's keeping their promises and who's falling behind.