This story originally appeared on Yale Environment360 and is part of the Climate Desk collaboration.

As public concern about plastic pollution rises, consumers are reaching for canvas bags, metal straws, and reusable water bottles. But while individuals fret over images of oceanic garbage gyres, the fossil fuel and petrochemical industries are pouring billions of dollars into new plants intended to make millions more tons of plastic than they now pump out.

Companies like ExxonMobil, Shell, and Saudi Aramco are ramping up output of plastic—which is made from oil and gas, and their byproducts—to hedge against the possibility that a serious global response to climate change might reduce demand for their fuels, analysts say. Petrochemicals, the category that includes plastic, now account for 14 percent of oil use and are expected to drive half of oil demand growth between now and 2050, the International Energy Agency (IEA) says. The World Economic Forum predicts plastic production will double in the next 20 years.

“In the context of a world trying to shift off of fossil fuels as an energy source, this is where [oil and gas companies] see the growth,” said Steven Feit, a staff attorney at the Center for International Environmental Law, an advocacy group.

And because the American fracking boom is unearthing, along with natural gas, large amounts of the plastic feedstock ethane, the United States is a big growth area for plastic production. With natural gas prices low, many fracking operations are losing money, so producers have been eager to find a use for the ethane they get as a byproduct of drilling.

“They’re looking for a way to monetize it,“ Feit said. “You can think of plastic as a kind of subsidy for fracking.”

America’s petrochemical hub has historically been the Gulf Coast of Texas and Louisiana, with a stretch along the lower Mississippi River dubbed “Cancer Alley” because of the impact of toxic emissions . Producers are expanding their footprint there with a slew of new projects, and proposals for more. They are also seeking to create a new plastics corridor in Ohio, Pennsylvania, and West Virginia, where fracking wells are rich in ethane.

Shell is building a $6 billion ethane cracking plant—a facility that turns ethane into ethylene, a building block for many kinds of plastic—in Monaca, Pennsylvania, 25 miles northwest of Pittsburgh. It is expected to produce up to 1.6 million tons of plastic annually after it opens in the early 2020s. It’s just the highest-profile piece of what the industry hails as a “renaissance in US plastics manufacturing,” whose output goes not only into packaging and single-use items such as cutlery, bottles, and bags, but also longer-lasting uses like construction materials and parts for cars and airplanes.

Since 2010, companies have invested more than $200 billion in 333 plastic and other chemical projects in the US, including expansions of existing facilities, new plants, and associated infrastructure such as pipelines, says the American Chemistry Council, an industry body. While some are already running or under construction, other projects await regulators’ approval.

“That’s why 2020 is so crucial. There are a lot of these facilities that are in the permitting process. We’re pretty close to it all being too late,” said Judith Enck, founder of Beyond Plastics and a former regional director for the US Environmental Protection Agency “If even a quarter of these ethane cracking facilities are built, it’s locking us into a plastic future that is going to be hard to recover from.”

The impact goes beyond the waste problem that is the focus of public concern. Although plastic is often seen as a separate issue from climate change, both its production and afterlife are in fact major sources of greenhouse gas emissions.