Here’s a bit of irony for you. If you were around in the eighties, you would have been bombarded with messages that aerosols like in spray paint or deodorant were significant contributory factors to the creation of the hole in the ozone layer. This was true. Aerosols at the time used a compound called CFCs that would break down ozone and they were duly (and correctly) banned. Fast forward thirty years and the villain may yet become the hero if the clever folk at Harvard have anything to say about it.
Particulates in the air (ie – the stuff that’s in your aerosol cans) have the capacity to cool down the Earth as they can – in sufficient numbers – block the sun’s rays from hitting the Earth. If that sounds a little counter-factual, think on what happens when a cloud passes over you on a sunny day: it gets colder. Now imagine that the particulates involved were denser than water vapour like, say, volcanic ash, and you’d be right in thinking that the cooling effect would be increased. Volcanic eruptions have had measurable impacts on temperatures around the world over the years and are one of the possible causes of the ‘Mini Ice Age’ from roughly 1600-1800.
As we continue blithely down a carbon-burning road to environmental disaster and as temperatures on Earth continue to climb, scientists considered the artificial mass spraying of a very high volume of particulates into the atmosphere as a possible solution to the impending consequences of our utterly unfathomable, unthinking fossil fuel economy.
The way this would be done was with sulphate aerosols that would reflect light. But there was one teeny-weeny problem. These sulphate particles would go on to produce sulphuric acid in the stratosphere; acid which would then go on to break down ozone. So we would have been trading a colder Earth for a less-protected one, since (in case you didn’t know) the ozone layer is what’s responsible for shielding us from UV radiation. Hardly an ideal solution.
So the research team from the Harvard John A Paulson School of Engineering and Applied Sciences (a name that just trips off the tongue) ditched sulphates and ended up, through scholarly thinking with a hefty side order of applying science, with calcites instead. “Essentially, we ended up with an antacid for the stratosphere” said Frank Keutsch, a co-author of the paper.
These calcites are will not only reflect light but will also neutralize emissions-borne acids. So they will both cool the planet and soak up all the crap that we – in our infinite wisdom – have already put up there. The net result of this would be to slow global warming and to actually repair the ozone layer at the same time.
The team caution, however, that this is not a magic bullet that gives us a free pass to be idiots and keep burning fuels whilst putting our fingers in our ears and denying our actions have consequences. No indeed. Rather the team liken it to a painkiller. It might help alleviate the symptoms of global warming but it won’t address the cause. That one requires us to set aside short-term interest and think longer term.