HFCs are such huge contributors to global warming that they’ve been dubbed “super climate pollutants.” While carbon dioxide is the best-known greenhouse gas, these fluorinated gases, which leak out of refrigerators and air conditioners and wind up in the atmosphere, cause the earth to heat up hundreds and sometimes thousands of times more than C02 does. (Despite being a major problem when emitted from burning fossil fuels, carbon dioxide — which is referred to as R-744 in the cooling sector — turns out to be environmentally friendly when used as a natural coolant in refrigerators.)

The chemicals now in use, hydrofluorocarbons, or HFCs, many of which were first made by DuPont and have been passed onto Chemours, are massively heating the planet while they keep us cool. It’s a strange heating spiral – in a warming world, we need more refrigeration to cool ourselves and our food, but the use of these cooling systems accelerates climate change, which in turn leads us to use more coolants.

There may be no more important products for this warming age than refrigerants, which represent a multibillion-dollar industry, as Chemours pointed out in its letter requesting the meeting. The huge demand isn’t just because of the growing need to cool people and food as the earth’s temperature spirals upward. It’s also because a global effort is underway to shift away from the current generation of chemicals that serve this purpose.

Chemours did not respond to several requests for comment for this story. The EPA did not provide an on-the-record comment.

The company was also seeking the environmental agency’s help staving off competition in a field it already dominates. Michael Garry, the only U.S.-based employee of Shecco, which advocates for the climate-friendly refrigerants, regularly finds himself outgunned by Chemours and Honeywell and other chemical companies when he tries to spread the word about natural refrigerants at supermarket conferences and other gatherings where he might reach users of the alternative technology. “These are billion dollar companies. They have all the clout,” Garry said of the HFO manufacturers. “It’s a whale to a minnow.”

“They are greatly exaggerating the safety concerns,” Keilly Witman , a refrigeration consultant and former EPA staffer, said of Chemours’ statement. “They pick out an issue that effects a small area and imply that it’s true for the entire natural refrigerant world.”

Of particular concern were “so called ‘natural’ refrigerants,” as Chemours described the naturally occurring chemicals, including propane, iso-butane, ammonia, air, water and carbon dioxide, which are increasingly relied on for cooling around the world. In its letter , Chemours acknowledged that natural refrigerants “may indeed be preferred for some uses and equipment types,” but also described the alternative products as having “poor energy performance, higher operating costs, and severe safety risks” — which is largely incorrect. While some of the cooling systems using natural refrigerants may be more expensive than HFO-based systems, many are less expensive and the substances themselves, which aren’t patented, always cost less than HFOs. And though the natural refrigerants propane and iso-butane are flammable, so are HFOs.

According to records released by the EPA in response to a Freedom of Information Act request by the Sierra Club, the chief executive of Chemours, Mark Vergnano, along with two of his company’s government affairs staff and an outside lobbyist, met with then-head of the EPA Scott Pruitt and several EPA staffers in May 2017 to talk about its new refrigerants, known as HFOs. Chemours, which had spun off from DuPont in 2015, had invested hundreds of millions of dollars in these chemicals, which are designed for use in supermarket chillers, ice rinks, air conditioning, freezers, and refrigerators, as it wrote in a May 2017 letter requesting the meeting with the EPA. Beyond wanting swift approval for its new products, the company was seeking help to stave off competition, asking the EPA to “help protect U.S. leadership in [the refrigerant] space and protect significant new U.S. investments the company has made.”

When executives from the Chemours Company met with top officials of the Environmental Protection Agency last year, they were seeking the Trump administration’s help to launch a new generation of chemicals and steer the nation through an important juncture. The U.S. — indeed the entire world — is in the process of phasing out chemicals used for cooling that, in a bitter twist, contribute significantly to climate change. Chemours wanted the EPA’s help not just to promote its next generation of coolants to replace the chemicals now used in refrigerators and air conditioners (among other products), but to stave off the use of more environmentally friendly options.

R-404a, which is an HFC that was developed by DuPont and is now sold by Chemours, for instance, has a global warming potential, or GWP, of 3,922, meaning it traps 3,922 times more heat than carbon dioxide does. Around the world, as air conditioners proliferate to cope with climate change, HFCs have become the fastest-growing greenhouse gas emissions in every country on Earth.

The Kigali Amendment, an international accord passed in 2016, promises to phase-out HFCs, with the first drop in production and use starting in 2019. If fully implemented, the resulting reductions of HFC emissions are expected to help the world avoid a 0.5 degree Celsius increase in global temperature by the end of the century. While 42 countries have ratified the Kigali Amendment, the U.S. has yet to sign onto it (Republicans are split over the agreement, with a faction of extreme climate deniers arguing against ratification).

Makers of natural refrigerants and HFOs agree that HFCs should be phased out, but haven’t decided what should replace them. A coalition of HFO manufacturers called the Alliance for Responsible Atmospheric Policy, which includes Chemours, Daikin, and Honeywell, wrote to President Donald Trump in June, encouraging him to submit the Kigali Amendment to the Senate for ratification.

These companies use an economic, rather than environmental, rationale to justify the switch from HFCs. In its letter to Trump, the coalition made clear that its interest lay in in the opportunity the agreement offers to dominate the refrigeration industry:

We believe this action will help secure a position of strength for American companies in a highly competitive global market for next generation air conditioning, refrigeration, thermal insulation, aerosols, medical uses, fire suppression, semiconductors and other technologies that utilize fluorocarbons. With Senate ratification comes American technological leadership, and a head-start for American industry in the global race to provide the world with state-of-the-art products.

The industry push for its new chemicals hinges on the idea that HFOs are “very low GWP alternatives” to HFCs, as Chemours described them in its letter to EPA. The chemicals do contribute less to global warming than the older chemicals. But, in terms of both climate and toxic pollution, HFOs present environmental hazards that natural refrigerants do not.

Part of the problem is that, while they are advertised as climate-friendly and, on their own, may have GWPs in the single digits, HFOs are often sold in mixtures with HFCs, which means that they can still have a dramatic warming effect on the Earth. Chemours markets Opteon XP10, a blend of refrigerants containing HFOs, as having a “low global warming potential,” yet its GWP is actually 573 — meaning it traps 573 times as much heat as CO2. Similarly, Chemours has touted Opteon XP40, the HFO blend used in the NHL’s Greener Rinks Initiative, as having a “proven” low global warming potential, though its GWP is 1,282.

In comparison, natural refrigerants, which can serve many of the same purposes, have a global warming potential between zero and four.

While Chemours is hoping that the EPA will help it get the best return on its investment, others argue that environmental consequences, rather than business interests, should drive decisions about which refrigerant chemicals we use.

“It makes sense to go with the lowest GWP possible for every sector,” said Avipsa Mahapatra, climate campaign lead of the Environmental Investigation Agency. Though different cooling systems use differing refrigerants depending on their purpose and size, in most cases, natural refrigerants can do the job, according to Mahapatra.

One area in which HFO use has already taken hold is in car air conditioning. HFO-1234yf, which is sold in its pure form and has a GWP of just four — about 350 times better for the climate than the chemical it replaces. While the natural refrigerant CO2, which is being introduced in some cars, has a negligible climate advantage over HFOs in the car market, it offers the possibility of reducing two toxic chemicals associated with HFO-1234yf. One of them was, until recently, on its way out. Carbon tetrachloride, which has been deemed a probable carcinogen by the EPA and is now one of the first 10 hazardous substances being evaluated under the new chemical law, is already a widespread air pollutant, responsible for more than three cancers for every 1 million people in every census tract in the country, according to EPA data.

Because it was used to make some of the chemicals now being phased out by the Montreal Protocol, the use of carbon tetrachloride was decreasing, according to a recent EPA report. But because the chemical is also used to make some HFOs, including HFO-1234yf, demand for carbon tetrachloride is now expected to increase by 50 percent in coming years, according to comments submitted to the EPA by three environmental NGOs.

Some HFCs and HFOs, including the one used in car air conditioners, also degrade into a persistent toxic substance called trifluoroacetic acid, or TFA, which persists in the environment and can be toxic to aquatic plants. While its potential long-term effects on people and other animals are still being studied, TFA is accumulating in water around the world and is extremely hard to remove from drinking water. According to a 2015 study done in Beijing, the amount of TFA in water increased 17-fold over a 10-year period. A Norwegian Environment Agency report recommended “phasing out HFOs (and consequently TFA)” to protect public health, though the chemicals are just now being phased in.

Together, the range of issues has led groups like Greenpeace and the North American Sustainable Refrigeration Council to push for the next generation of coolants to be natural refrigerants, rather than HFOs. Shecco’s Garry sees the chemicals as the latest in a long cycle of regrettable substitutions. “It’s foolish in the long term to take the chemical companies’ newest version of synthetic refrigerant when every preceding version has been a problem,” he said.

Indeed, the history of using fluorinated gases for cooling is long and troubled. DuPont introduced the first of these chemicals, CFCs, in the 1930s. They remained on the market for decades before scientists discovered that CFCs were eroding the layer of ozone that protects the Earth from much of the sun’s ultraviolet radiation. CFCs were also widely available for more than a decade after that 1974 discovery, as DuPont questioned the science about the effect of CFCs on the ozone and waged a well-financed public relations campaign against the effort to restrict their use.

It was only after it received assurances from U.S. officials that European competitors wouldn’t be able to get a competitive advantage through the treaty that DuPont ultimately changed course and supported the Montreal Protocol, which phased out CFCs and other ozone-depleting chemicals in 1987. Although the company had produced hundreds of millions of pounds of the chemicals that caused the planet-altering ozone problem, it was given much of the credit for the treaty’s success in phasing out CFCs.

The phase-out of CFCs ultimately proved to be a boon to DuPont, as the company became one of the major suppliers of HFCs, the refrigerants that replaced ozone-depleting chemicals.

Now, as the world moves ahead with the effort to replace those replacements, DuPont’s offspring, Chemours, could be headed for a similar payday from their next round of refrigerant gases. But the question of what replaces HFCs has the power to dramatically impact the climate and water pollution around the world.

In many parts of the world, companies have already begun disrupting the reliance on a series of fluorochemicals with natural refrigerants. Some governments in Europe and Japan have encouraged that switch. In Switzerland, for instance, carbon dioxide is now the standard coolant use in all supermarkets by law. These carbon dioxide-based systems now account for 12 percent of the European market and 5 percent of supermarket coolers in Japan, where the government subsidizes natural refrigerant cooling.

The natural refrigerants also present a particular opportunity for developing countries, according to Helena Molin Valdés, director of the Climate and Clean Air Coalition Secretariat at the U.N. Environment. In developed countries that rely on cooling systems that were designed to use HFCs, it can be easier to switch to HFO products, which are often designed to be “drop-in replacements.” But because many of the developing countries have yet to switch to HFCs, “they have the opportunity to do what we call leap frogging and not do the regrettable substitutions,” said Molin Valdés. “Developing countries can go directly to the alternatives.”