An international agreement to ban ozone-depleting chemicals, signed in 1987 in Montreal, is now showing results in the atmosphere. The Montreal Protocol is considered one of the most important climate treaties in history, but can we do it again with climate change?

It was 30 years ago this month that a large area of ozone depletion was discovered over the South Pole by the British Antarctic Survey. Although it looks like a hole in satellite images, it is a region where the amount of ozone that naturally gathers around the poles of the planet is severely reduced.

A recent study at the University of Leeds used simulations to show what the atmosphere would be like today had the Montreal agreement not been signed. The researchers found that not only would the ozone hole over the South Pole be 40 per cent larger, but there would be a second large hole over the Arctic and less ozone over mid-latitudes, where most people live.

This would have increased levels of UV radiation from the sun by 10 per cent, causing more skin cancers, especially in Australia and New Zealand.

Ozone is a form of oxygen with an extra atom, O3 instead of the O2 we live on. It is found high up in the stratosphere and acts as a filter for ultraviolet radiation from the sun. 

Ozone is a natural sunscreen that protects life on the surface of the planet. In fact, it could be said that without ozone, life would have had a much more difficult time emerging onto land and we humans likely wouldn't be here.

The culprit in the destruction of ozone was a class of chemicals, including Chlorofluorocarbons, or CFCs. They were very useful products that could easily turn from liquid to gas and back again at close to room temperatures, making them convenient for refrigeration systems, or to provide the pressure to get products out of aerosol cans. These extremely stable chemicals were favoured because they did not mix with products, so there were no unwanted tastes or odours.

At first glance, they seemed to be quite inert and harmless. But millions of refrigerators and air conditioners and aerosol spray cans were being used around the world, releasing huge amounts of CFCs into the atmosphere.

When atmospheric scientists began looking at the chemistry happening in the stratosphere over the South Pole, they discovered a strange chemical interaction was taking place between long-lasting CFCs, ice crystals, the sun, and ozone, with the result that ozone was chemically broken down. And since the CFCs were so stable, they remained in the atmosphere for a long time, which meant that as long as they were being used, the situation would only get worse.

Ozone Rebounds

NASA images shows the ozone layer above Antarctica on: Sept. 17, 1979 (top left), Oct. 7, 1989 (top right), Oct. 9, 2006 (lower left) and Oct. 1, 2010 (lower right). Earth's protective but fragile ozone layer is starting to rebound, says a United Nations panel of scientists. (NASA/Associated Press)

The severity of this problem was so obvious, it took only two years to come up with an international ban on CFCs, and Canada hosted the United Nations Conference in Montreal in 1987. The deal, signed by 46 countries, went on to become the first UN treaty to receive universal ratification.

By 2010, worldwide consumption of 98 per cent of all the chemicals in the protocol had been phased out.

The speed and effectiveness of this agreement was due to the fact that industry was able to come up with a quick solution to the problem — a CFC substitute that was only slightly different, called HCFC, which performed the same function but was not as destructive (although they, too, are being phased out in favour of even better substitutes).

That meant we didn't have to give up refrigeration or aerosol cans. It was an invisible change that did not interfere with our accustomed lifestyle.

Now, we are faced with a new culprit that is changing the nature of the atmosphere, increasing the level of carbon dioxide.

The UN is once again trying to come up with an international agreement to reduce emissions, but it's not so easy this time because people fear that giving up fossil fuels could affect their lifestyle and jobs. We don't want to give up our cars, trucks, SUVs, motorcycles, snow machines, personal watercraft, airplanes, trains, oil and gas furnaces, coal-fired generating stations, etc, etc. And, we also can't afford to shut down all the industries that support those products, because it would collapse the world economy.

But we can take another lesson from the Montreal Protocol ... find substitutes.

Zero-emission electric or hydrogen vehicles, alternative energy production, energy efficient homes, better designed cities — are all on the table, but still considered by many to be too expensive.   

It's ironic that Canada hosted the most effective climate agreement of all time, because now we are considered one of the obstacles when it comes to treaties on climate change.  

Too bad we can't regain our international reputation as a country on the forefront of environmental stewardship.

Once, we got it right. Why can't we do it again?