Their leverage rapidly vanishing under the shadow of an incoming administration hostile to action on climate change, U.S. negotiators nonetheless notched a significant win this week at the United Nations’ climate summit with help from the private sector.

ClimeCo, a global sustainability company based in Pennsylvania, announced agreements with four Chinese chemical companies at the COP29 gathering in Azerbaijan that will all but eliminate emissions of nitrous oxide from the companies’ chemical plants. 

Also known as N2O, nitrous oxide is a climate super pollutant, 273 times more effective at warming the planet than carbon dioxide on a pound for pound basis. Often referred to as the “forgotten greenhouse gas,” the pollutant is the third leading driver of climate change and the primary cause of ongoing loss of the atmospheric ozone layer that protects people from harmful ultraviolet radiation.

U.S. Department of State officials singled out N2O emissions from chemical plants in China as a “huge prize” in potential greenhouse gas emission reductions as part of a White House summit on climate super-pollutants earlier this year.

A global assessment by the U.N. Environment Program released on Tuesday found that a 40 percent reduction in human-caused N2O emissions by mid-century would be equal to eliminating six years of carbon dioxide emissions from fossil fuels and would prevent 20 million premature deaths through improved air quality. 

The report noted that the agricultural sector, where N2O is released from nitrogen-based fertilizer, is far and away the largest source of this pollution and holds the greatest potential for emission reductions. However, the authors also stated that emissions from chemical plants “could be almost completely eliminated and are the least expensive.”

ClimeCo anticipates that the annual emission reductions from the four plants will total 45 million metric tons of carbon dioxide equivalent per year. In climate terms, that’s like taking 11 million gas-powered cars off the road or shutting down 12 coal-fired power plants.

“The whole thing is like a pinch-me moment,” said William Flederbach, ClimeCo’s CEO. “It’s just beyond my expectations.”

The chemical plants located in eastern and southern China produce adipic acid, used to make nylon 6,6, a high-strength polymer the automotive industry puts in everything from seat belts and tires to engine parts. N2O is an unwanted byproduct of adipic acid production.

The combination of N2O’s potency as a greenhouse gas and the large volume of the pollution generated in adipic acid production means these plants can have an outsized impact on the climate.

Adipic acid manufacturers in other parts of the world voluntarily developed and installed pollution controls to destroy N2O starting in the 1990s. China followed suit a decade later, spurred by lucrative incentives through a U.N. program known as the Clean Development Mechanism. However, the incentives hastened the collapse of adipic acid production in other countries while production in China soared.

When money for the U.N. program dried up in the early 2010s, Chinese companies in all likelihood stopped destroying their N2O emissions, a major setback for efforts to address climate change that was detailed in an Inside Climate News investigation in 2020.

Rick Duke, the U.S. deputy special envoy for climate, highlighted the potential for large, low-cost N2O emission reductions from chemical plants in China at a July event in the U.S. Duke said 200 million tons of carbon dioxide equivalent per year could be eliminated from industrial facilities in China by 2030.

“That is over 50 coal-fired power plants’ worth of emissions every year, year on year, that we simply can get at by working together,” Duke said. It’s “just a huge prize.” 

One group answering the call was ClimeCo, which recently helped the largest adipic acid producer in the U.S. effectively eliminate its remaining N2O emissions.

The company is now working with the Chinese plants to install pollution-control systems that use a catalyst to help break down N2O into harmless nitrogen and oxygen gas. 

ClimeCo is overseeing the installation of the pollution-control systems along with real-time monitoring equipment that quantifies the volume of N2O destroyed. The company will sell carbon-offset credits for a portion of that eliminated pollution.

The credits that can be earned are limited in an effort to avoid the sort of over-incentivization that occurred under the U.N.’s Clean Development Mechanism. Current offset requirements include a 90 percent baseline for emissions reductions. This means that if an adipic acid plant in China were to reduce its emissions by 95 percent, it could only earn credits on the final 5 percent of those reductions.

Pollution controls currently being installed on production lines at the four plants will destroy approximately 97 to 98 percent, according to Flederbach.

Climate advocates expressed mixed feelings about the voluntary approach.

“Is this kind of carbon offset and carbon credits the best way, or could there be alternative ways?” asked Li Shuo, director of the China Climate Hub at the Asia Society Policy Institute.

Carbon markets have come under increasing scrutiny in recent years. Actual emission reductions from carbon market projects are six times lower—just 16 percent—of the emission reductions claimed in carbon market projects, according to a comprehensive study published Thursday in the journal Nature Communications.

“There are really persistent and severe integrity problems in the existing markets,” said study co-author Lambert Schneider, research coordinator for international climate policy at the Oeko-Institut, a nonprofit environmental research institute based in Germany.

A report Schneider and others authored in 2010 was among the first assessments that exposed problems with the Clean Development Mechanism’s N2O projects in China that ultimately led to defunding such projects.

Schneider subsequently served as an advisor to Climate Action Reserve, a nonprofit based in Los Angeles, as the group developed rules for N2O emission reduction credits from adipic acid plants in the U.S. The group sought to include guardrails to avoid the same over-incentivization that plagued the prior U.N. program.

Climate Action Reserve later developed a similar protocol for adipic acid plants in China, though Schneider was not involved with the development of these rules. 

Schneider said he hasn’t made a thorough investigation of the ClimeCo projects in China. But based on what he does know about the chemical plants and Climate Action Reserve’s protocol, he said the carbon offset projects may actually overachieve on emission reductions. 

“For one carbon credit that you buy, you do not just get one ton, but you may get even more than one ton of emission reductions,” he said.

In addition to ClimeCo’s projects, U.S. nylon company Invista is also working with adipic acid manufacturers in China to help them reduce their N2O emissions.

Invista is a subsidiary of Koch Industries, a fossil fuel refining and chemical production corporation whose owners Charles Koch and, formerly, the late David Koch funded many of the organizations that have challenged the science of climate change and worked to block government action on it over the past quarter-century. 

Invista is also a spinoff of DuPont, a chemical company that led the voluntary development of N2O pollution controls for adipic acid plants in the 1990s.

Invista licensed its abatement technology to three adipic acid plants in China to help them reduce their emissions. The company said it anticipates the partnerships will soon achieve reductions totaling approximately 30 million tons of CO2 equivalent per year. 

The partnerships allow Invista to purchase abated, or low-carbon, adipic acid that the company can then use in its own nylon 6,6 production. The ability to produce nylon 6,6 from low-carbon adipic acid could give Invista a competitive advantage with its customers, automobile manufacturers that are increasingly seeking to source low-carbon materials for their vehicles.

Greg Lemon, a spokesperson for Koch Industries, said one of the three adipic acid manufacturers in China has completed a successful deployment of the N2O abatement technology.

The combined ClimeCo and Invista projects could reduce 75 million tons of carbon dioxide equivalent from adipic acid plants in China. That’s nearly 40 percent of the 200-million-ton prize identified by Duke, the U.S. deputy special envoy for climate.

“The global momentum behind cutting non-CO2 greenhouse gases is strong and growing,” U.S. climate envoy John Podesta said at a summit on greenhouse gases other than carbon dioxide at the U.N. climate conference on Tuesday. “It is bigger than any one country, and it will take collective cooperation to get it right.”

Avipsa Mahapatra, climate campaign director for the Environmental Investigation Agency U.S., a nonprofit based in Washington, said she was disappointed by the lack of stronger action from the U.S. and China, the world’s leading emitters of industrial N2O.

“What we’ve left on the table is a complete elimination of these emissions,” Mahapatra said.

“It is bigger than any one country, and it will take collective cooperation to get it right.”

— John Podesta, U.S. climate envoy

The U.S. emits far less N2O from industrial sources than China and is on track to achieve a more than 50 percent reduction in these emissions from 2020 levels by early 2025. 

A key next step for the U.S. and other countries will be to include emission reduction targets for all greenhouse gases, including N2O, in their next round of Nationally Determined Contribution targets under the Paris climate agreement.

U.S. officials may submit their targets prior to President-elect Donald Trump’s inauguration. However, Trump has pledged to pull the U.S. out of the Paris agreement once in office—for a second time.

Liu Zhenmin, China’s special envoy for climate change, said the country will continue to promote research on controlling emissions of N2O and other non-CO2 greenhouse gases. However, Liu added that “China is still facing challenges in key areas, such as the lack of effective emission reduction technologies, accurate monitoring equipment and standardized protocols.”

Li, of the Asia Society, said regulators in China “need to step up their game” with better monitoring, a more top-down regulatory approach and emission control targets.