Smoking, cancer and global warming
Posted on 23 February 2011 by Stephan Lewandowsky
A short piece for the general audience of RTR radio, Perth, Australia.
(listen to the original audio podcast)
Some 50 years ago Humphrey Bogart died of throat cancer after decades of chain smoking. Did tobacco kill him?
Probably, but not certainly, because some non-smokers also get cancer.
Nat “King” Cole died in 1965 of lung cancer at age 46. He was a heavy smoker, did tobacco kill him? Probably, but not certainly, because some non-smokers also get cancer.
Monty Python’s Graham Chapman died at age 48 from throat cancer. Did his pipe kill him? The guy down the street who’s now dying of lung cancer before he had a chance to quit, did he get killed by tobacco?
In each case, the answer is probably, but not certainly.
In fact, none of the 15,000 people who die from smoking in Australia every year were definitely killed by tobacco!
Not Humphrey Bogart, not “King” Cole, not the guy down the street. No one definitely ever died from smoking.
And yet they all probably died prematurely because of tobacco.
Tobacco kills. It is therefore meaningless to ask for absolute certainty in each instance. Fortunately, people understand that: In California, for example, the rate of smoking has declined from 44% to less than 10% over the last few decades, showing that people can act on risks without requiring certainty.
The same logic applies to climate change. Were the devastating floods in Queensland aggravated by climate change? Quite possibly but not certainly. Was the devastating cyclone in Queensland stronger than it would have been without a changing climate? Quite probably but not certainly. Were the devastating bush fires on Melbourne’s Black Saturday exacerbated by climate change? Very likely but not certainly. Was 2010 the hottest year ever recorded because of climate change? Almost certainly, but not definitely.
What is certain, however, is that the increasing frequency of those extreme events was predicted by climate scientists long ago. And what is almost equally certain is that those events would not have happened at all, or would have been more benign, if we hadn’t been emitting all that CO2 for the last 100 years.
So to reduce the risk from floods or fires, we must cut CO2 emissions for the same logical reason that people quit smoking to preserve their health.
An earlier version of this post attracted more than 60 comments which were very helpful in putting together this final version. I have incorporated many of the thoughtful comments and omitted some of the bits that were not easy to follow.