Methane is a significant cause of global warming, second only to carbon dioxide in its contribution as a greenhouse gas. Human activity is a major contributor to methane emissions, chiefly from the energy industries. According to the Environmental Defense Fund (EDF), the oil and gas industries alone release 75 million metric tons each year. In response, the organization is planning to launch MethaneSAT to identify major sources of methane emissions and identify opportunities for reduction. If all goes the plan, EDF hopes to launch the satellite early in 2021.

In 2016, methane made up 10 percent of greenhouse gas emissions in the USA. EDF says its goals for MethaneSAT are to gauge the size of methane emissions, find their source, identify the best opportunities for reductions and monitor the success of those reductions.

"Cutting these emissions is the fastest, cheapest thing we can do to slow the rate of warming today, even as we continue to attack carbon dioxide emissions," EDF says. "We've learned that emissions are much higher than either industry or government previously recognized, and occur throughout the supply chain. The challenge is, the sources are intermittent, unpredictable and widespread, making it hard to predict where they'll occur."

Unlike government-funded multi-use satellites, MethaneSAT will look for methane alone, which EDF claims will help to launch the satellite more quickly and expensively. Despite this, it claims the satellite will provide the highest-resolution measurement of methane gas yet.

EDF says the satellite will be capable of checking in on around 50 major emissions sites once every 7 days or less. It thinks this is enough to keep tabs on 80 percent of the world's oil and gas production. However, EDF says it will have the precision to track smaller sources of emissions, such as cattle feedlots. After coal, oil and natural gas production, agriculture is a close second as a human-made source of methane emissions. Solid waste landfill sites also contribute to atmospheric methane levels, as do the biomass and biofuel industries.

The plan is to share the captured data openly, in the hope that there will be an inherent incentive to cut emissions and mend leaks. The value of the methane saved will more than cover the costs of repairs and improvements, the theory goes. However, the data could also prove vital to industry regulators, which will surely be interested in better sources of methane emissions tracking.

Though atmospheric methane occurs in smaller quantities than carbon dioxide, it's far more potent. Per unit weight, methane traps 72 times as much heat as carbon dioxide in its first 20 years in the atmosphere. Thanks to the speed of its decay, this drops to a factor of 34 over a 100-year period. Its short lifespan in the atmosphere makes methane a good target for reducing the impact of global warming, since benefits will be felt sooner. Eventually, methane gas in the atmosphere decays into carbon dioxide. Nevertheless, atmospheric methane levels have doubled in the last 150 years.

EDF is working with Harvard University and Smithsonian Astrophysical Observatory to develop the satellite.

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