On 4 March 2024, a new methane-observing satellite, MethaneSAT, was launched atop a SpaceX Falcon 9 rocket and successfully placed in orbit [
1]. Developed by the New York City, NY, USA-headquartered Environmental Defense Fund (EDF) in partnership with the New Zealand Space Agency and funded by multiple philanthropic donors including the Bezos Earth Fund, the spacecraft promises to greatly improve scientists’ ability to pinpoint and monitor methane emissions, particularly those related to the oil and gas industry.
With a global warming potential more than 80 times greater than CO
2 over a 20-year period, methane has been called “a climate blowtorch” [
2]. On the plus side, the greenhouse gas is comparatively short-lived in the atmosphere, so efforts to cut methane emissions have the potential to yield near-term climate benefits. As concerns about climate change intensify [
3], understanding and mitigating methane emissions have become increasingly urgent objectives.
MethaneSAT is the latest in a growing array of orbiting methane monitoring satellites (
Fig. 1) [
4]. What sets it apart are three key factors: its combination of detection sensitivity with wide coverage, its ability to produce maps of the size and location of emissions, and data transparency. Its makers claim it will monitor emissions from areas accounting for more than 80% of the global production of oil and gas as it circles the planet every 95 min, targeting 200 km × 200 km areas [
5]. Its high-resolution infrared instrument can detect, over large areas, methane emissions as low as 5 kg·h
−1 in a single square kilometer [
5]. “We have never had this quality of data for any greenhouse gas,” said Steve Hamburg, EDF’s chief scientist.
For now, MethaneSAT is undergoing vigorous testing. “We are doing controlled methane-release experiments, which we are monitoring with the satellite and also the aircraft version of MethaneSAT’s instrumentation, called MethaneAIR,” said Hamburg. “We have the highest-precision greenhouse gas measuring satellite ever produced and flying, so we need to really understand what that means for data collection.”
While the MethaneSAT team plan to publicly release some data through the end of 2024, the three-pronged package of online, freely-available-to-all MethaneSAT data products is scheduled to go live in early 2025, Hamburg said. One product will reveal total methane emissions across the world’s major oil and gas production regions, known as basins. A second will map the distribution of those emissions across each basin. The third will focus on detailing high-emitting point sources.
The anticipated power of MethaneSAT lies in its potential to support climate accountability. This is important and timely, given the latest data showing that global atmospheric methane continues to climb to record levels. According to the US National Oceanic and Atmospheric Administration (NOAA) (
Fig. 2), methane levels in 2023 rose to 1923 parts per billion (ppb), 11 ppb higher than in 2022 [
6]. While it is estimated that the global energy sector accounts for slightly lower methane emissions than agriculture, the largest human activity related contributor to atmospheric methane (
Fig. 3) [
7], the straightforward preventability of industrial methane leaks—and the potential cost savings for producers associated with plugging existing leaks—has made them a key focus of attention for mitigation efforts.
The Global Methane Tracker 2024 report, published by the Paris, France-based International Energy Agency (IEA), concluded that the production and use of fossil fuels emitted about 120 Mt of methane in 2023 [
8]. It also found that, compared to 2022, satellite-detected very large methane leaks from the energy sector increased by more than 50% to more than 5 Mt. That included a major well blowout in Kazakhstan that continued unabated for more than 205 days, during which it emitted an estimated 130 000 t of methane [
9].
Pinning down the true amount of the energy sector’s methane emissions has proved difficult. According to a recent study published in the journal
Nature that integrated about a million aircraft observations taken from sites covering a large portion of onshore oil and gas production in the United States, official estimates of US methane emissions provided by the US Environmental Protection Agency (EPA) were only about one-third of the actual emissions seen in the surveyed regions [
10]. The study’s authors suggest the discrepancy is due in part to reliance on incomplete data, including from ground-based surveys that can miss a substantial number of large, point-source methane emissions.
Much of the energy sector’s methane emissions are a result of “low probability but high consequence” leaks from point sources, said the study’s lead author Evan Sherwin, now a research scientist at Lawrence Berkeley National Laboratory in Berkeley, CA, USA. Sherwin led the study while at Stanford University (Stanford, CA, USA). “Of the total emissions directly observed by the aircraft, both at well sites and over gas transportation and processing infrastructure, more than half were emitted by only about 1% of sites,” said Sherwin, who also helped perform the testing of MethaneAIR [
11], MethaneSAT’s airplane-based precursor and counterpart.
“Given that oil and gas extraction and their associated pipelines are giant networks, there is really no substitute for measuring just about everything,” said Sherwin. “A MethaneSAT-type approach, combined with comprehensive aerial point-source surveys where possible, could become the gold standard for the regional estimation of methane emissions.”
Using MethaneSAT in combination with MethaneAIR to better identify and quantify such point sources should help support geopolitical efforts to reduce methane emissions that have recently gained momentum. For example, at the December 2023 28th United Nations (UN) “Conference of the Parties” Climate Change meeting in Dubai, United Arab Emirates, 52 companies, together responsible for nearly half of the world’s fossil fuel production, pledged to reach near-zero methane emissions associated with natural gas production by 2030 [
12].
This pledge, however, has been met with skepticism. In a previous interview with
Engineering, Rob Jackson, professor of Earth system science at Stanford University and chair of the Global Carbon Project, said: “The chance they will get to near zero emissions by 2030 is near zero” [
13]. Jackson pointed out that natural gas, which is mostly methane, is the fastest-growing fuel in the United States, primarily replacing coal rather than transitioning to renewables. In a similarly sober vein, the UN Secretary General António Guterres said: “The fossil fuel industry is finally starting to wake up, but the promises made clearly fall short of what is required” [
14]. Guterres also noted that methane emissions from human activities are currently on track to increase by 13% by 2030.
On 8 March 2024, the EPA introduced a “Final Rule” to strengthen, expand, and update methane emissions reporting requirements for the US oil and gas industry [
15]. The rule addresses the gap between industry-reported and actual methane emissions “by facilitating the use of satellite data to identify super-emitters and quantify large emission events, requiring direct monitoring of key emission sources.” With its ability to provide comprehensive, regular data on methane emissions from oil and gas producing basins across the United States, MethaneSAT has the potential to play an important independent oversight role in the push to reduce these emissions.
Beyond anthropogenic methane emissions, methane arising from natural sources, particularly tropical wetlands, is also increasingly of concern. The world’s wetlands are by far the largest natural source of atmospheric methane, contributing about one-third of the total combined natural and anthropogenic emissions annually (
Fig. 3) [
7]. The problem is that global warming appears to be amplifying those emissions [
16].
Tropical wetlands are particularly sensitive to warming for two key reasons. First, warming releases more methane through boosted microbial activity. Second, increased rainfall causes the wetlands to expand and creates more anerobic conditions for methane production. This positive feedback mechanism means that, even under the best-case scenario of the Intergovernmental Panel on Climate Change (IPCC)—Representative Concentration Pathway 2.6 (RCP2.6)—under which humanity manages to significantly reduce its greenhouse emissions, wetland methane emissions are nevertheless projected to rise significantly. Indeed, under RCP2.6, these natural emissions are projected to surpass human methane outputs by the end of this century, promoting further warming [
16]. And with the recently reported record surge in global wetland methane emissions from 2020 to 2021 [
17], the IPCC’s best-case scenario already appears wildly unrealistic.
The problem could be even worse accounting for potential methane contributions from wetlands of the future that are currently encased in ice in the higher latitudes, said Zhen Zhang, a professor at the Institute of Tibetan Plateau Research, Chinese Academy of Sciences, in Beijing. “Based on our simulations, it could be that when the temperature reaches a certain point, the permafrost will thaw, expanding wetland coverage and adding a lot of additional methane to the atmosphere,” said Zhang, who coordinates the wetland section of the Global Methane Budget for the Global Carbon Project.
Given the future’s likely increased methane from natural sources, it appears that the best hope for reducing atmospheric methane in the short term is to focus on anthropogenic emissions, particularly those from the global oil and gas industry where relatively easy and possibly cost saving fixes may be possible. “You cannot mitigate methane emissions from natural sources, because they are so widespread,” said Zhang. “We need to put more effort into mitigating human-caused methane emissions to offset the positive feedback loops of natural sources.”
EDF’s Hamburg, for one, is optimistic. He sees MethaneSAT’s data—“CCTV [closed-circuit television] for methane”—providing the basis for a “race to the top” by oil and gas companies. “With MethaneSAT’s high-quality data, any company with low methane emissions can show conclusively that they are doing better than the average,” he said. “That way, the big, national buyers of liquid natural gas can understand the climate implications of who they are buying from—this transparency is critical.”
PDF
(548KB)
