The nonstick pan has become one of climate change’s stickiest problems in recent years. Teflon, the magical chemical that has allowed fried eggs to glide off the pan onto breakfast plates for decades, is derived from the chemical HCFC-22. But HCFC-22 has an unfortunate side effect: Its production also generates HFC-23, a greenhouse gas that is 14,700 times more powerful than carbon dioxide in heating the planet.
Only about a couple of dozen factories in China are responsible for producing two-thirds of the world’s HCFC-22. So climate advocates rejoiced when Beijing signed onto the Kigali Amendment to the Montreal Protocol in 2021, which required all signatories to immediately stop emitting HFC-23 using widely available emissions destruction technology. Past efforts to cut the climate super pollutant in China had failed; but the binding international agreement carried more heft and promise.
The reports that China is required under Kigali to submit to the United Nations Environment Program appear to show that it has been working, with China’s HFC-23 emissions reported at relatively low levels in 2022, the most recent year for which data is available.
However, the atmosphere tells a different story.
In a recent study published in the journal Communications Earth & Environment, scientists used data from remote monitoring stations around the globe and found that as of 2023, global HFC-23 emissions were five times higher than countries had reported to the U.N. in recent years. And the study attributes 40 percent of global emissions to eastern China.
The fact that HFC-23 emissions from China and other countries continue to reach the atmosphere in large volumes poses a test to the Kigali Amendment, which has been ratified by more than 160 countries since 2016. And it comes at a vulnerable moment for international climate action writ large, with U.S. President Donald Trump once again withdrawing the United States from global efforts.
HFC-23 may be little known compared to carbon dioxide, but the pollution is significant—global HFC-23 emissions in 2023 were equal to the annual greenhouse gas emissions of 48 million automobiles or 55 coal-fired power plants. “There is a powerful greenhouse gas that countries are, for whatever reason, not destroying, even though they should and have the means to, and that’s quite concerning,” said Ben Adam, a researcher in the School of Chemistry at the University of Bristol and the study’s lead author.
Where exactly China’s HFC-23 emissions are coming from isn’t entirely clear yet, but scientists have some hypotheses.
The production of a variety of hydrofluorocarbons (HFCs) is known to generate HFC-23, but scientists have assessed HCFC-22 to be the main culprit.
Over two decades before joining Kigali, the Chinese government attempted to address that problem without much success. During a U.N. program in the 2000s and an additional Chinese subsidy program from 2015 to 2019, HCFC-22 producers in the country installed equipment to destroy HFC-23. According to the Chinese Ministry of Ecology and Environment, 17 out of the 19 active HCFC-22 producers had installed incinerators as of 2021.
Incinerators installed and properly operated at the chemical plants can destroy 99.9 percent of waste HFC-23 at little cost. But perverse incentives and loopholes in the policies, previously documented in an investigation by Inside Climate News, allowed total emissions to continue rising to their high point in 2019 even as some of the HCFC-22 companies abated their emissions.
In signing onto the Kigali Amendment, Beijing took steps to reverse that trend. In September 2021, after Kigali went into force in China, the environment ministry issued a notice requiring all HCFC-22 and HFC producers to fulfill the international agreement’s requirement to eliminate emissions to the extent possible.
Joining the agreement seems to have made some difference. By 2023, the last year of data included in the study, HFC-23 emissions in eastern China had dropped by a third from the high point in 2018. Emissions did tick up slightly from 2021 to 2023, but they stayed well below their 2018 peak, even as China’s production of HCFC-22 continued rising.
However, Chinese regulations haven’t been strong enough to eliminate the problem. In 2021, the environment ministry didn’t establish any specific emissions standard or penalties for noncompliance. In January 2024, the ministry followed up with draft rules laying out how companies should measure and report their emissions. That guidance set a standard of destroying 99.99 percent of HFC-23 emissions.
But after more than a year, the rules have yet to be put into effect. In April, the ministry published a new national plan on the implementation of the Montreal Protocol, including enhanced measurement, reporting, and monitoring of HFC-23 emissions from HCFC-22 plants, but again the plan did not include any details on enforcement.
The Ministry of Ecology and Environment did not respond to requests for comment.
Hu Jianxin, a professor of environmental science and engineering at China’s Peking University who has conducted research on the super pollutant for years and contributed to the January 2024 draft rules, said HFC-23 “is one of the most priority issues” for the Ministry of Ecology and Environment. “They really care about this issue, and also a lot of people are actually working on auditing.”
He added that he was not sure why the rules haven’t been implemented but pointed to pushback from the affected plants. “The companies still complain,” he said.
Not counting initial capital costs, which many plants recouped through the subsidy programs, Chinese chemical plants can destroy HFC-23 at a cost of approximately $0.30 to $0.60 per tonne of CO2 equivalent. That makes destroying HFC-23 one of the most cost-effective ways to combat climate change.
Costs for capturing CO2, by comparison, range from $15 to $342 per tonne, with additional costs for storage, according to the International Energy Agency.
But without subsidies or another way to profit from the emissions abatement, it is still an extra cost for companies. Hu pointed to a plant in China that has captured HFC-23 and converted it back into HCFC-22 as a potential model for other companies to reap economic benefits from cutting pollution.
The latest atmospheric readings pointing to continued emissions from China have not gone unnoticed by the Montreal Protocol. Emissions estimates in the 2024 study are similar to those published by the Montreal Protocol’s own Scientific Assessment Panel in September.
“The science is pretty clear,” said David Fahey, director of the U.S. National Oceanic and Atmospheric Administration’s chemical sciences laboratory in Boulder, Colorado, and a co-chair of the Scientific Assessment Panel for the Montreal Protocol. “We kind of put it on the table for the [countries’] delegates to decide: Is this important enough to do something about?”
Whether they take action may hinge on the meaning of four words.
Under the Kigali Amendment, countries agree to curb HFC-23 emissions from HCFC-22 and other HFC production “to the extent practicable.” That phrase leaves significant room for interpretation.
“The term ‘to the extent practicable’ is not defined in the Protocol or in decisions by the parties, nor are there specific targets/schedules set for reduction in HFC-23 emissions to be achieved,” Megumi Seki, the executive secretary of the U.N.’s Ozone Secretariat, which oversees the Montreal Protocol, said in an email. “As long as the parties report some amounts destroyed per facility, we would understand that the party destroyed its HFC-23 emissions to the extent practicable.”
Climate advocates disagree.
“‘Practicable’ does not mean whether it was costly or not,” Avipsa Mahapatra, climate campaign director for Environmental Investigation Agency U.S., a nonprofit based in Washington, D.C., said. “It means whether it was technologically feasible.”
Stephen Andersen, director of research at the Institute for Governance and Sustainable Development (IGSD), a Washington, D.C.-based environmental nonprofit, said the insertion of the “extent practicable” language was an unfortunate part of the “horse trading” that goes into any multilateral agreement. Andersen attended the Montreal Protocol 2016 meeting in Kigali, Rwanda, when the amendment was first adopted.
However, he added, the agreement now needs to be re-energized to reduce climate pollution.
“Someone has to pressure the Montreal Protocol to do what they need to do before it gets worse,” he said.
Seki said that the amount of HFC-23 that countries report as destroyed is “taken at the face value” and that there are currently no cases of noncompliance under investigation.
But Mahapatra said the current study suggests that this approach isn’t working. “The parties and the protocol urgently need to move beyond this hand-waving self-reporting that we have seen so far, and really look into their real numbers,” Mahapatra said.
The HFC-23 issue was high on the agenda at a Montreal Protocol meeting last fall, but the talks only led to limited action.
At the meeting, a representative from the United States, speaking on the behalf of the United States and Canada, called for member countries with substantial differences between reported emissions and atmospheric measurements to reduce their emissions. As of 2023, U.S. chemical plants’ HFC-23 emissions were compliant with the Environmental Protection Agency’s Kigali Amendment regulations, according to the agency. But China pushed back, saying more research and greater technical capacity were needed, and that China shouldn’t be singled out for a global problem.
A formal decision, which was reached on a consensus basis among member countries, called for the voluntary sharing of atmospheric monitoring data. It also invited member countries with HCFC-22 plants to report how they calculate HFC-23 emissions and share information on best practices to reduce emissions. In short, the group did not agree to any actions that would force countries to address the glaring emissions problem, and the Kigali Amendment itself does not contain any penalties for failing to reduce HFC-23.
In the coming years, the United States may not be a voice in the room pushing for more accountability. Trump has led a broad effort to pull the United States out of international institutions and environmental pacts, and it remains unclear what role the United States will play in the Kigali Amendment going forward. The U.S. State Department did not answer questions about the country’s involvement in the Montreal Protocol’s next annual meeting scheduled for this fall.
HCFC-22 plants are an obvious focus for reducing emissions because they are an established source of HFC-23 and are widely considered to be the main contributor. Yet even if the Montreal Protocol did step up scrutiny of HCFC-22 producers and China tightened its own oversight, the HFC-23 problem wouldn’t fully disappear. Scientists have found that other chemical plants also release HFC-23 emissions, and they’re debating the extent to which those other plants are contributing to the problem.
HFC-23 is known to be produced or leaked from a wide range of other HFC plants and through the use of HFC-23 to manufacture semiconductors as well as other products. In recent years, Peking University’s Hu and his colleagues have also measured small amounts of HFC-23 at various fluoride chemical plants in China. They are still far from knowing the proportion of HFC-23 coming from each non-HCFC-22 source, but he estimates that the total may be significant given the scale of China’s fluorochemical industry.
“If there are too many of these kinds of small chemical substances, in aggregate it is still a big figure,” Hu said.
The transformation of HCFC-22 into Teflon is one major concern for scientists. That process can release additional HFC-23 emissions beyond the original production of HCFC-22. Another recent study, based on local air monitoring in southern China, found that this process “could be emerging as an increasingly significant emission source of HFC‐23” and merits further attention since those plants fall outside of the Kigali Amendment’s reporting requirements.
“It is probably the most important of the remaining sources, but it is nowhere near as important [as HCFC-22 production],” Adam said.
There’s also always the possibility of illegal production of HCFC-22 as a refrigerant, which would not be subject to monitoring. HCFC-22 was once commonly used for refrigeration and air conditioning, but China is phasing out its use in those industries under the Montreal Protocol, as the chemical depletes the Earth’s ozone layer, which protects the planet from harmful ultraviolet radiation from the sun.
The phasing out of the refrigerant could have had the unintended consequence of causing illegal production at chemical plants that would be unlikely to incinerate their HFC-23 waste gas, Clare Perry, a climate campaign leader at the Environmental Investigation Agency U.K., a nonprofit based in London, said. A limited number of cases of illegal HCFC-22 production have been reported in China in recent years, though the extent of that production remains unclear.
Scientists have also pointed to a less direct source: the degradation of hydrofluoroolefins, or HFOs, in the atmosphere. HFOs are a new class of chemical refrigerants that have a far lower direct impact on the climate than HFCs. However, as they break down, they can form HFC-23.
“It’s a very complex ‘whodunit,’” Perry said. “It might be like that Agatha Christie one where everybody did it.”
One solution may be to simply make less of the chemicals that produce such potent greenhouse gases. One way to do this would be to limit the production of HCFC-22 and other chemical feedstocks under the Montreal Protocol, Andersen, of IGSD, said.
“These factories are just big chemical cocktail factories,” Perry said. “As long as you’re making products with chlorine and fluorine, you are basically risking having emissions of things that will either deplete the ozone layer or warm up the climate.”
As a starting point, environmental advocates say China must keep a much closer eye on its HCFC-22 factories to ensure they aren’t emitting or leaking HFC-23. Beyond that, Hu said that China needs to step up monitoring around fluoride chemical plants to better understand the extent of emissions originating from those facilities.
At the same time, global emissions monitoring remains critical—and is potentially under threat. HCFC-22 is also manufactured in India, Russia, and other parts of China. However, the Advanced Global Atmospheric Gases Experiment (AGAGE), the global monitoring network used to detect HFC-23 emissions, is unable to quantify emissions from these locations due to a lack of monitoring stations in these regions.
And that capacity could decrease further. NASA’s Earth Sciences Division provides at least partial funding to five of the AGAGE network’s 16 air monitoring stations worldwide. The Trump administration sought to cut funding to the division in half in the 2026 budget request it sent to Congress earlier this month.
“Everybody is afraid that they want to blind the science,” Andersen said. “Some people think if you don’t see it, it won’t matter. It’s the ostrich with its head in the sand.”
NASA has already canceled 145 grants and contracts totaling $113 million since late January, according to an online database compiled by the Planetary Society, a space advocacy group. Grants to two U.S. universities for the AGAGE network remained active as of May 2, NASA confirmed in response to a public records request by Inside Climate News.
Curbing global monitoring would put U.S. manufacturers at a disadvantage, because plants operating in areas with no oversight could forgo pollution controls and their associated costs, Andersen said. “For the U.S. and Europe, who have done a good job of reducing their emissions, while other countries are blowing HFC-23 into the atmosphere, this is unfair competition, this is outrageous,” Andersen said.
This article was co-reported with Phil McKenna of Inside Climate News. A version of the story was also published by Inside Climate News.
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