BOULDER, Colo.—Scientists, governments and environmental groups are focused on what may be the first global detective story about emissions. It’s an effort to determine how many rogue businesses may have violated the Montreal Protocol by selling insulation containing a banned chemical that is 5,000 times more powerful as a global warmer than carbon dioxide.

China has mounted an investigation of more than 1,000 companies to see which Chinese firms violated international law by using trichlorofluoromethane—also known as CFC-11—in plastic foam insulation. Investigators say it’s possible that thousands of tons of the insulation was made for homes and other buildings and distributed throughout the country.

The chemical was banned by the 1987 treaty because it’s in the family of substances described by scientists as the “main culprits” in the depletion of the Earth’s atmospheric ozone layer, which protects people from the sun’s cancer-causing ultraviolet radiation. The chemical can also harm crops.

The Montreal Protocol was hailed as one of the world’s most powerful legal tools against future environmental harm. Its timetable called for a total ban of CFC-11 by 2010, but Stephen Montzka, a research scientist here at NOAA’s Global Monitoring Division, found something strange in samples of the atmosphere he was testing in 2014.

NOAA’s data had showed a steady decline of the banned gas until about 2013, but the new samples collected in flasks showed what he called suspicious statistical “bumps and wiggles” on a weekly basis. “I couldn’t believe somebody was not paying attention to this,” he recalled in an interview. “Or did I make a mistake in the lab?”

Mistakes were certainly possible. There are at least three different ways to identify the invisible, odorless gas, and Montzka checked them all. They showed that the tiny percentage of CFC-11 in his samples was still declining, but the rate of decline had slowed down. In some samples, it appeared to be increasing.

But where in the world were the increases coming from?

It took Montzka and other investigators three years to narrow it down. There are two global atmospheric monitoring networks in the world. NOAA, a unit of the Department of Commerce, has one. A second, larger one is run by agencies and institutions from an international group of countries including the United States. It’s called the Advanced Global Atmospheric Gases Experiment (AGAGE).

Montzka went there to check his findings. Ray Weiss, a geochemist at Scripps Institution of Oceanography at San Diego, and one of the leaders of the AGAGE network of 50 global observation stations, is happy that he did. “Steve gets very high marks for looking at his data,” explained Weiss.

Evidence of the strange slowdown in the decline of CFC-11 had also begun to appear in the AGAGE data. “Steve looked at it more closely than we did,” explained Weiss. The two investigators and their teams began putting their pieces of this vast puzzle together.

One problem they wrestled with is there are gaps in their networks. Both systems rely on remote observation points where the atmosphere is thoroughly mixed. That allows them to get a global average of chemicals in the atmosphere without being overwhelmed by pollutants from industrial areas.

Montzka came to suspect the increases were coming from the Northern Hemisphere. He had data from Hawaii that pointed to Asia as the most likely source.

Scientists at both networks used models to backtrack weather patterns that carried CFC-11 to their observation posts. By May 2018, Montzka had enough evidence to publish a paper in Nature, one of the world’s leading science journals.

It sounded an alarm.

Someone appeared to be making new supplies of CFC-11. By Montzka’s estimate, emissions had risen to 67,000 metric tons per year. It was more than just a couple of factories’ worth of production and enough to delay the recovery of the ozone layer, he estimated, by as much as a decade.

Critics of the finding argued that the chemical, formerly used as a refrigerant, among other things, could be leaking from old cooling systems. Others speculated that CFC-11 emissions were leaking from previously made insulation stocks in buildings or stored in warehouses.

A nonprofit in Washington, D.C., the Environmental Investigation Agency, which specializes in undercover investigations, mounted one quickly in China. They visited a number of companies and found employees in 18 of them who explained they had decided to revert to using CFC-11 to make insulation foam and panels because it was a better and cheaper substance to use.

“It was very common knowledge that this was a banned substance,” explained Avipsa Mahapatra, the leader of EIA’s climate campaign. “Clearly there were connections with local enforcement agencies in some places.” She recalled how people at some local businesses bragged to EIA’s sleuths that they had warning calls from municipalities when government inspectors were about to make a visit.

China was having a building boom. There was high demand for the insulation, and the risks “were very low,” Mahapatra explained. Some companies rented factories to make insulating foam using CFC-11. “Others were offering to sell it on the internet.”

One result was “Blowing It,” an EIA report released in July 2018 that helped provoke a national investigation of over 1,172 Chinese companies. There have been a few reported arrests and tons of confiscated CFC-11, but Mahapatra, who recently returned from Beijing, explains that government officials told her the investigation has been complicated. “I don’t think we have the final numbers yet,” she said.

Another result was a statement from the China Plastics Processing Industry Association, which said its members would reject the use of illegal chemicals.

Montzka and Weiss are among the 32 scientists who co-authored a new Nature article, released yesterday. It says they tracked at least 40% to 60% of the global CFC-11 emissions to two of China’s northeastern provinces: Shandong and Hebei. The study finds “no evidence” of a significant increase in emissions from other Asian countries or other regions of the world where there are observation posts that might detect them.

The working group that is monitoring the problem for the Montreal Protocol has met twice recently, and Montzka said he’s convinced that Chinese investigators “are eager to get at this.”

Weiss agreed but noted that the world’s knowledge of how far the CFC-11 problem has spread is limited to what the global networks can detect and measure. At the moment, scientists can observe the eastern part of China, western Japan, the Korean Peninsula, and parts of North America, Europe and southern Australia.

He noted that there are large swaths of the world that are unobserved. That’s a problem, he thinks, that could haunt global leaders in the future. It may eventually appear in the accounting process needed to determine which countries are curbing their emissions to meet the Paris Agreement’s goal of limiting global temperatures to 1.5 degrees Celsius by midcentury.

“What’s going to happen when some nations fall short?” Weiss asked. “There’s going to be finger-pointing. Some will say, well, we did our share.”

World leaders haven’t devoted enough resources to the observation systems that eventually pinpointed the illegal CFC-11 emissions, he believes. Without more funding, there won’t be a truly global view of the prohibited chemicals, he warns.

“We’ve done it for nuclear proliferation,” Weiss added, noting that there are 80 observation stations and some 300 seismographs poised to pinpoint clandestine nuclear weapons tests anywhere around the world. “We ought to be doing the same thing for ozone and climate change.”

Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news