Originally published in December 2011.
It is one of the oft repeated clichés of politics that if we do not learn from history, we will be forced to repeat it. If we are to adopt this mantra for environmental issues, then the story of Sir Thomas Midgely must stand as one of the most important lessons history had to teach us.
Midgely’s first brush with history came during an era when he worked on cars and engines, in which time one of the problems with petrol engines was ‘knocking’. ‘Knocking’ is the incomplete combustion of fuel, which leads to fuel vapour coming out of the exhaust of the car. This resulted in terrible air pollution, and further made engines less efficient.
It was Midgely who discovered the first solution to this problem – leaded petrol. Leaded petrol was far less prone to ‘knocking’ and seemed to produce much cleaner exhaust fumes. Cars using this new fuel also burnt less petrol. Midgely’s development was hailed as a great breakthrough for the environment – and it was… sort of. What Midgely and his contemporaries didn’t know was that the lead would cause massive environmental damage. Lead is highly toxic to most plants and animals and can cause problems in the brain, blood, kidneys, digestive system and nervous system; several very good reasons not to put it in petrol (or to line ones aqueducts with it).  But it was years before anyone realised that Midgely’s breakthrough was actually doing more harm than good.
But Midgely’s career was not over yet. Turning his attention from engines to refrigerators, he began to develop refrigerants that were less volatile and toxic. His great breakthrough was named Chlorofluorocarbons – better known as CFCs.
Like leaded petrol, CFCs were initially thought to be an extremely clean solution to an existing problem. CFCs were non-flammable, non-toxic and apparently benign. Following Midgely’s discovery, the use of CFCs spread widely throughout refrigerator manufacturing and (most famously) was used in the production of aerosols.
Of course, we know how this story ended. The damage that CFCs cause to the environment turned out to be massive, creating a hole in the Ozone layer. While this is now a well known fact, it is worth pausing to consider that at the time, no-one could have conceived of a gas that could punch a hole in the atmosphere of a planet. 
Midgely’s life was one of dedication and devotion to science and the environment, and his legacy must surely go down as one of the tragic ironies of history.
But we’re past this kind of problem are we not? Are we? Let us ponder Hybrid Cars for a moment.
Hybrid cars are marvels of modern automotive design. They contain batteries which recapture energy lost when the car brakes, which is then used to power the car, thus saving fuel. Brilliant. Simple.
However the metals used in the construction of Hybrid Engines and Drives are rare and difficult to mine. Most of them are mined in China, using inefficient and dangerous methods, before being shipped abroad to car factories (often in Canada, incidentally). The amount of damage done to the environment through mining and shipping far outweighs that which is prevented by the use of hybrid cars. 
However much we think we know about the environment, much of what we do may in fact be causing more harm than good. Dealing with climate change is possibly the biggest and most important challenge in the modern world. But we need to be cautious whenever we introduce a miracle technology, or whenever we think we have solved the crisis in one fell stroke.
Sir Thomas Midgely, we feel your pain.
 The United States Environmental Protection Agency, Lead in Paint Dust and Soil: Basic Information. Available at http://www.epa.gov/lead/pubs/leadinfo.htm#health
 Ministry of Economy Trade and Industry, History of Chloroflourocarbons, Available at http://www.meti.go.jp/policy/chemical_management/ozone/files/pamplet/panel/08e_basic.pdf
 Chanaron, J.J. & Teske, J. (2007) The hybrid car : a temporary step, International Journal of Automobile Technology & Management, Vol. 7, n°4, pp. 268-288.