Industries in northeast China have dumped large amounts of ozone depleting gas into the atmosphere in violation of an international treaty, say global scientists.
And this slows down the recovery rate for the hole in the crucial ozone layer.
The ozone layer is a region of the Earth's stratosphere that acts essentially as a shield and absorbs most of the sun's ultraviolet (UV) radiation.
When scientists discovered in 1985 that there was a hole in the Antarctic and in Australia, the news was very disturbing. After that, we all teamed up and banned the use of harmful gases that destroyed Earth's protective layer in the 1987 Montreal Protocol, and since then it has been recovering more or less slowly.
China is a signatory to The Montreal Protocol, however, looks as if the country has not met its end to the agreement.
Since 2013, the annual emissions of a banned chemical called CFC-11 from Northeast China have risen overnight by about 7000 tonnes in the journal Nature.
"This increase accounts for a significant proportion (at least 40 to 60 percent) of the global increase in CFC-11 emissions," they wrote.
Before it expired, CFC-11 or chlorofluorocarbon-11 was widely used as a refrigerant and foam insulation in the 1970s and 1980s. The chemical is one of the main causes of ozone depletion.
Since the ban, the concentration of chemical in the atmosphere has steadily declined, but last year scientists were shocked to find that the pace of this slowdown halved from 2013 to 2017. Since the chemical does not occur in nature, the change could only be caused by new emissions.
Using high-frequency atmospheric observations from Gosan, South Korea, and Hateruma, Japan, along with global monitoring data and the atmospheric model for chemical transport After simulations, investigators investigated the probable culprit and point the finger at East China.
Environmental Investigation Agency reports from last year looked at Chinese foam factories in the coastal province of Shandong and the Hebei inland province surrounding Beijing.
] The suspicion was heightened when the authorities later closed some of these facilities without explanation.
Paul Fraser, an honorary member of the Australian CSIRO Climate Science Center and co-author of the paper, said that while East China accounts for about half of the increase in CFC-11, global scientists lack the technology to absorb large parts of the rest monitor the world.
Together with other scientists, he presented the data to Chinese authorities last year and is confident that action will be taken to reduce the damage caused by emissions.
"They were worried, it was clear, I think … that they would tackle this problem," he told ABC Radio this morning.
So far, however, he has not seen or heard any signs that China has begun to fight the rogue factories deemed responsible.
Since scientists have noticed the chemical increase in the atmosphere early on, "we have a good chance of making sure they do not do too much damage," he said.
But more CFC-11 in the air could also prevent the ozone returns to normal levels. Scientists warn.
"If emissions do not go down, this may delay the recovery of the Antarctic ozone hole by decades," Fraser said.