As more people gravitate toward energy efficient appliances and building materials, a large number of older discarded appliances and building material appear to still pose a threat to the environment while sitting in the junk yard.
Researchers from MIT have traced unexpectedly high levels of chlorofluorocarbons (CFCs) to ‘large banks’ of discarded construction material and appliances, including building insulation foam, refrigerators, and cooling systems.
CFCs such as CFC-11 and CFC-12 were responsible for creating a hole in the Earth’s ozone layer, and after a worldwide ban on their production was put in place in 2000, most scientists expected their levels to drop.
While many consumers have moved on to greener and more energy efficient appliances and construction materials, the discarded equipment from before the ban continue to emit large amounts of CFCs (chlorofluorocarbons) from the junkyard
However, the team said that many of the same sources that emitted CFCs before the ban have continued to do so, even after their original owners have thrown them out and moved on to greener and more energy efficient alternatives.
The team published their findings in the journal Nature Communications, contradicting previous analysis that these banks would be too small to cause significant damage to the Earth’s protective ozone layer.
High in the atmosphere, the ozone shields the planet from harmful ultraviolet rays that can cause problems such as skin cancer and crop damage.
In 1987, countries around the world agreed in the Montreal Protocol to phase out CFCs.
The effect of the phase-out was observed in 2016, when scientists noticed the first signs of healing in the Antarctic ozone layer.
Based on these efforts, a United Nations report in 2018 predicted the upper ozone layer above the Northern Hemisphere would be completely repaired in the 2030s, while the Antarctic ozone hole should disappear in the 2060s.
But MIT researchers said that, if left unchecked, these banks, which are slowly leaking the CFC-11 and CFC-12 gases into the atmosphere, would delay the recovery of the ozone hole by six years and add the equivalent of nine billion metric tons of carbon dioxide to the atmosphere.
Susan Solomon, a professor of environmental studies at MIT, and a co-author on the study, said: ‘Wherever these CFC banks reside, we should consider recovering and destroying them as responsibly as we can.’
CFCs were banned worldwide in 2000 after they were linked to the growing hole in the ozone layer over Antartica
‘Some banks are easier to destroy than others. For instance, before you tear a building down, you can take careful measures to recover the insulation foam and bury it in a landfill, helping the ozone layer recover faster and perhaps taking off a chunk of global warming as a gift to the planet.’
The team also found high levels of another ozone-depleting chemical, CFC-113, which is being emitted into the atmosphere at a rate of seven billion grams per year.
This chemical is still being produced as a feedstock for the manufacturing of other substances, they said.
Based on their calculations, the researchers believe if all banks were destroyed back in 2000, the measure would have saved the equivalent of 25 billion metric tons of carbon dioxide between 2000 and 2020, and there would be no CFC emissions lingering now from these banks.
In a second scenario, the researchers said, if the CFC banks are dismantled in 2020, it would help the ozone layer recover six years faster.
WHAT ARE CHLORO-FLUOROCARBONS (CFCS)?
Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine.
They are used in the manufacture of aerosol sprays, blowing agents for foams and packing materials, as solvents, and as refrigerants.
CFCs are classified as halocarbons, a class of compounds that contain atoms of carbon and halogen atoms.
Individual CFC molecules are labelled with a unique numbering system.
For example, the CFC number of 11 indicates the number of atoms of carbon, hydrogen, fluorine, and chlorine.
Whereas CFCs are safe to use in most applications and are inert in the lower atmosphere, they do undergo significant reaction in the upper atmosphere or stratosphere where they cause damage.