Not only did the Montreal Protocol preserve the ozone layer, it also helped save the earth from a climate change time bomb.
The landmark ozone treaty was agreed 35 years ago this month, at a time when both climate and ozone science were far less developed than they are today. Nonetheless, all nations signed and accepted binding commitments to reduce the production, consumption and emissions of chemicals responsible for depleting the ozone layer, which shields the planet from the sun’s most damaging radiation. The same chemicals also happened to be immensely potent greenhouse gases, and reducing them bought the world valuable time to deal with the climate crisis.
“If we let it [chlorofluorocarbons (CFCs)] If we continued to grow, we would have had the effects of climate change that we’re feeling now … a decade ago,” said David Doniger, an attorney with the Natural Resources Defense Council who has worked on the issue since the 1980s. “And now things would be much worse.”
The protocol’s status as a climate agreement was bolstered by the 2016 Kigali Amendment – named after the Rwandan capital where the agreement was drafted – which targeted a class of refrigerants that were non-ozone-depleting but climate-damaging. Scientists say the global phase-out of hydrofluorocarbons (HFCs), which the US will join after a key Senate vote on Wednesday, has the potential to avoid half a degree Celsius of warming by 2100.
Scientists, lawyers and others who have studied the issue for decades say that long before international negotiators reached the deal on HFCs, the ozone deal had prevented a particularly harmful group of climate-damaging superpollutants from being burned into developing world air conditioners and refrigerators finally acquire.
David Fahey, director of NOAA’s Chemical Sciences Laboratory and co-chair of the Montreal Protocol’s scientific review board, was among the scientists who in 1987 flew a NASA research aircraft into the ozone hole that had appeared over Antarctica. At the time there were several competing theories as to why the hole appeared, he said.
But the NASA trip, he said, “created what we call a smoking gun that was really the definitive proof that chlorine destroys ozone on the scale that would cause the Antarctic ozone hole.”
The world reacted quickly.
“The same month we flew to Antarctica in southern Chile, the Montreal Protocol was signed in Montreal,” he said. “And it was basically signed without knowing for sure what caused the Antarctic ozone hole.”
The new agreement was not only a leap of faith from a scientific point of view, but also had characteristics that, despite far greater scientific certainty, have not been repeated in any subsequent climate agreement.
The treaty is universal with 197 member countries. It is legally binding, with penalties for countries that do not comply with its provisions. And it’s fully funded, meaning poorer countries that may not have been able to meet their chemical phase-out targets have received support from richer countries.
“There is no other forum that has these three dimensions,” Fahey said, noting that the 2015 Paris Climate Agreement is based on voluntary commitments with no penalties for violating them.
“Probably the underlying problem with the climate change situation is that we don’t have such a forum,” he said.
The key role of the DuPont scientist
Fahey said there was some understanding among scientists from the start that CFCs play a role in driving climate change and depleting the ozone layer. However, that role was illustrated by a scientific study he and four other scientists published in 2007 that looked at the “avoided worlds” by curbing the growth of the chemicals.
The report showed that without the Montreal Protocol, CFC use would have exploded. Under a conservative scenario, by 2010 the chemicals would have had greenhouse gas levels equivalent to almost half of carbon dioxide emissions from all other sources. The effects on the climate would have been catastrophic.
“I think the estimates are on the order of 2 degrees more by mid-century,” said Susan Solomon, a professor of environmental studies at the Massachusetts Institute of Technology.
She noted that if the world had continued on its path of increasing CFC use by 2050, the impact on the ozone layer would have threatened the health and survival of all living things on the planet, including humans. That could have been a forced action, she said.
“The good news is that we avoided all of that, and not only did we save the ozone layer, but we also made a huge gain for the climate,” she said.
While CFCs had the greatest impact on climate change, the chlorofluorocarbons (HCFCs) that temporarily replaced them still had significant climate impacts. Following the release of the 2007 paper, parties to the Montreal Protocol quickly shortened the treaty’s timeline for phasing out HCFCs, an adjustment that Fahey says was the first decision made under the Montreal Protocol to address global warming to reduce.
HCFCs have been replaced by HFCs. And HFCs that have no impact on ozone should be the ultimate goal of the Montreal Protocol. But they are climate superpollutants that can be thousands of times more potent than carbon dioxide.
Industry initially resisted the idea that the use of HFCs would have a significant impact on climate change. But Fahey credits an industry scientist, DuPont’s Mack McFarland, with changing the discussion.
“What Mack understood was the growth in the developing world,” he said. “For the developing world to catch up with the developed world.”
McFarland began speaking to delegates at the Montreal Protocol’s annual meetings about the role HFCs could ultimately play in driving climate change, Fahey said.
“This became one of his most important messages not only to the delegates but also to the scientists and technologists,” he said. “And it wasn’t particularly well received or adopted immediately. And even the scientists – I’m one of them – didn’t really get it, so to speak.”
But in 2009, McFarland, Fahey and the other scientists who contributed to the 2007 paper on the Protocol’s climate impact published a paper on the impact of operating air conditioning and refrigeration units around the world with HFCs. And its conclusions sparked the negotiations that eventually led to the creation of the Kigali Amendment eight years later.
Solomon said she was shocked when the Senate voted to join the Kigali Treaty by a majority of 69 to 27 this week. The agreement came into force on January 1, 2019 after reaching a ratification threshold. The US is the 138th country to sign up.
But Solomon said the US led the charge on global ozone depletion in the 1970s and 1980s.
“I think the main credit has to go to the American people,” she said.
aid to poor countries
When ozone science was in its infancy, shortly after scientists Sherwood Rowland and Mario Molina demonstrated that CFCs harm ozone in 1974, but before the extent of the damage was known, US consumers stopped listening to aerosol deodorants and hairsprays to buy.
The consequences were transformative. US personal care products accounted for 75 percent of global CFC consumption in 1974. Falling demand forced the industry to look for alternatives and made the Montreal Protocol possible.
And countries that are now leaders on climate change and other issues have stuck with their aerosol products.
“The Europeans were actually on the other side of the negotiating table,” Solomon said. “We said, ‘We should get rid of these compounds, we have substitutes, let’s move on. Let’s save the planet.’ And it was Europe that said, ‘Well, you know, we don’t see this need the way you do.’”
Solomon also credited former President Barack Obama and former Secretary of State John Kerry with creating the geopolitical momentum that carried Kigali across the finish line.
Nor are the direct climate benefits of protocol cuts in CFCs, HCFCs, and now HFCs the whole story.
Solomon noted that the protocol’s multilateral fund has helped poor countries gain access to refrigeration equipment, which reduces emissions from food waste and spoilage.
NRDC’s Doniger referred to a study published in Nature last year, which found that without the ozone conservation benefits of the Montreal Protocol, much less CO2 would have been absorbed over the past 35 years as the world’s biosphere decayed.
“The damage to trees and other vegetation would have meant that they would have absorbed much less CO2 from the atmosphere,” he said.
That Nature The study argues that the protocol helped avoid 2.5 degrees Celsius of warming. For context, scientists have warned that the world – and particularly vulnerable countries – will suffer catastrophic damage if warming exceeds 1.5°C.
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