MONTREAL, Rio, Paris and Kigali in Rwanda all have one thing in common – they’ve all been venues for hundreds of nations to discuss what to do about mankind’s continuing abuse of the atmosphere.

Rio and Paris hosted conferences on the challenge of increasing CO2 and the climate change that results, and the other two cities dealt with another impact of our ignorant attitude.

CFCs, chlorofluorocarbons, and HFCs, hydroflourocarbons, don’t occur naturally, unlike carbon dioxide, so we invented them for use in aerosol cans, refrigerators and air conditioning, the latter for both houses and cars.

At first we didn’t notice that the stable chlorine in the CFC is very long lasting and finally reaches the stratosphere where it destroys the ozone layer that’s our only protection from ultra violet radiation. Too much UV burns the skin and causes cancer as well as seriously damaging animal, marine and vegetable life systems. It’s not vanity that makes Australian cricketers smear sun cream on their faces.

The expanding hole in the ozone layer was tackled 1987 with the Montreal Protocol steadily phasing out CFCs, and it’s now slowly repairing, but it was a close shave. The chlorine part of the concoction was replaced with hydrogen and so the HFC was developed, which is less stable and so doesn’t reach the ozone layer.

However they’ve just realised that HFCs are much more effective than CO2 in warming the atmosphere, indeed molecule for molecule they are more than a thousand times better at trapping heat, particularly as they can remain there for one hundred years and longer. Though there’s far less of it, 190 countries have now accepted the damage caused, with the industrial west agreeing to try to stabilise its use by 2019, before gradually replacing it.

The developing countries have the same targets but for a later date, and they will have a task and a half. They have growing populations, with increasing wealth, and generally hotter conditions that mean air conditioning is now a priority for millions, as is a car, often one with leaking air conditioning. Add to this the tens of millions of fridges that indicate progress and an enormous amount of HFC gas will escape before it’s replaced by non climate changing gases.

Even though the hotter temperatures in much of Asia mean opening car windows is pointless, and food needs a fridge to stay edible, the increase in numbers still takes some believing. The number of cars in China, mainly air conditioned, has increased over ten times since the year 2000, and in India the number of fridges is doubling every six years.

That’s some volume of HFC gas to replace before it leaks out.