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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 one.

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.

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Comments 1 to 20:

  1. Do we have actual evidence that the frequency of extreme, or the magnitude, has increased? We need to allow for the improved detection, reporting, and documentation during the last couple of hundred years. For the past 60 years, I remember a constant stream of weather related extremes. The Australian Scientific Authority CSIRO has stated " No significant global trends have been detected in the frequency of tropical cyclones to date, and no significant trends in the total numbers of tropical cyclones, or in the occurrence of the most intense tropical cyclone, have been found in the Australian region." There was the Great Blizzard of 1888 in USA, and the 1900 drought in India which killed about 1 million people, and the Yellow River Flood in China in 1887 which also killed over 1 million people. There was the cyclone in Cape York Australia in 1899 where 400 people died. Can you provide some definitive data to substantiate an increase in natural weather disasters. I like to have a strong data base before I depend on this type of argument.
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  2. I think I get the point the author is trying to make, and yes, it is an important point, but I think he is making it unreasonably difficult for himself to make this point when he says, "Not Humphrey Bogart, not “King” Cole, not the guy down the street. No one definitely ever died from smoking." Please, please think of a better way to put this.
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  3. I can't provide definitive data for all weather disasters, but an article came out just last week in Nature ( called "Human contribution to more-intense precipitation extremes" which links heavy rains to human-induced increases in greenhouse gases.
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  4. @ rjacobsen0 There was also another article in Nature, though it only examined one specific flood event ( Real Climate had a good write up on both papers (
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  5. rjacobsen0 - thanks for the reference. I had a look, but it's only a summary, and I tried to check out the data sources. What I found is that over the past century, there has been increased precipitation in some areas, and decreases in others. For example, the contiguous USA has seen an increase of about 6% over the past 100 years, but tropical areas (Asia,) Southern Africa, and the Mediterranean have experienced a decrease. It's also significant that cities have experienced increased precipitation due to the urban heat island effect (increased heat leads to local upward air movement, so more thunderstorms). This effect should be deducted, as it will confound the null hypothesis if urban data is included. However, it seems that "globally, there has been no statistically significant overall trend over the past century". While there's lots of models that suggest this could happen, I can't find much actual data to back it up. Gruber and Levizzani have a fairly comprehensive report on this covering the past 30 years, and show no significant global change in precipitation.
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  6. I like your expositions on the logic (and lack thereof) of different lines of argument a lot. They are very helpful tools for laypeople to make sense out of debates on complex issues.
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  7. Cigarette smoke is very dangerous, especially over the long term. With over 4000 chemicals, many of the effects are now shown in causal linkages. True, no one can be said to have died 100% from smoking alone, but it is pretty clear that cigarettes cause cancer, strokes and heart attacks. The human system, as complex as it is, and variable, for that matter, smoking really does kill.I am not so sure that we can lay the same robust claim for C02 as of yet.
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  8. Chemist1... I believe the point that gets continually made is that we are rolling the dice. Based on the broad scientific research it's very likely that doubling CO2 will raise global temperature by about 3C. Regardless of whether you agree with that position, that is the current consensus of the published literature. So, there are unknowns. The effect might be less that 3C. They might be more. They could be a good bit more but it's unlikely to be a good bit less. We are rolling the dice none-the-less. We do not know what number the dice will land on. But we do have a choice about what numbers the dice will NOT land on. Same with smoking. I could smoke a pack a day for the rest of my life and never get cancer. You can never smoke a cigarette in your life and still get cancer. It's a roll of the dice, but one that you can influence where the dice may land.
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  9. Chemist1,
    I am not so sure that we can lay the same robust claim for C02 as of yet.
    Spoken like a true 1960s tobacco lobbyist. I am very certain we can lay that same robust claim for CO2, and have been able to do so for quite some time. The science is pretty voluminous and convincing, just as it was in the seventies for tobacco. But the tobacco industry, and people themselves, found it very easy to close their eyes to the truth for very many decades. I'd like to say that they only hurt themselves in doing so, although I think my own health insurance premiums say otherwise (being far higher than necessary, to pay for past smokers' heart and lung disease and lingering deaths). But not so with climate change. You don't get a free pass on this one, and we don't get to say (with detached sympathy) "poor guy, what a way to go, if only he'd listened to the science." Your "not so sure" had better be accompanied by some very careful, intense, open-minded and educated scrutiny, because if not your hesitance and inability to make a decision is going to contribute to causing a lot of suffering.
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  10. Chemist1, could you provide the proof that smoking actually kills ? While you are gathering that information, perhaps you should read what others (shall we call them 'smoking kills' deniers) have to say : "...the world data contradicting the notion that smoking kills, and that smokers statistically belong to the lower classes, thus are at higher risk of disease and early death by the myriad of factors in their life - stress, poor diet, poor healthcare etc, plus the fact that smokers are less likely to take as much interest in their health as non-smokers - after all, if they smoke believing it will kill them, why would they be otherwise healthy?" Plenty more 'proof' here. (I really hope those 'rel="nofollow"' values actually work !) Just how do you begin to attempt to convince those who refuse to accept reality ?
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  11. JMurphy - this is a foolish comment you quoted. There is statistical conclusion at extremely high probability level that smoking kills people. The factors of stress, diet etc have all been accounted for in the studies. If someone smokes, we don't know they will die of lung cancer, but they have a significantly increased possibility of death by lung cancer. Take, 10,000 smokers, and some will die of lung cancer. To compare this with the likelihood of doubling CO2 will cause a 3 degC temperature increase is not valid. There is no data to back this up - only computer models and theory which are still based on very limited understanding of many contributing factors. If someone says that doubling CO@ might result in a 1 degC increase, then I'll accept that as consistent with known science. Anything beyond that is just guess work at this stage.
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  12. 11 rhjames absolutely correct. Just to add a little: Many of the chemicals in cigarette smoke individually have support from numerous studies providing a some causal links between repeated exposure and cancer incidence and prevalence as well. In addition, global warming itself is not falsifiable, while other empirical studies are. 1 degree means nothing.
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  13. Here. Now I know arguments from statistical uncertainty and probability may be invoked but the sample sizes, the replicability in actual individuals and groups of people,e the random assignment, the years of robust research and qualitative analysis provide the actual proof and not just 'evidence.' Newer published data:
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  14. rhjames, don't tell me you believe all those elitist scientists and their dodgy/fraudulent/wrong/biased/etc data ? And you believe that it is a consensus ? Well, you know how wrong any consensus can be, don't you ? Anyway, here are more 'facts' from a 'proper' scientist working tirelessly to expose the truth like a modern-day Galileo : It's Official - Smoking Doesn't Cause Lung Cancer... As to your belief about climate sensitivity, perhaps you had better read this thread (How sensitive is our climate? - there are also Basic and Intermediate versions available) and post there to show which "known science" leads you to trust a figure of "a 1 degC increase".
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  15. Chemist1, it's no use posting results of searches which will lead to biased work subsidised and backed by big government and the Pharma industry - haven't you learnt the ways of those who are underpinning the AGW 'scam' ? I want 100% evidence giving physical facts that prove that a smoker will die of lung cancer.
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  16. rhjames: "What I found is that over the past century, there has been increased precipitation in some areas, and decreases in others." erm, both imply change, compared to the past! One wouldn't expect the same patterns in every location, that would be silly.
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  17. rhjames: "only computer models and theory which are still based on very limited understanding of many contributing factors." I suspect very much that the details of all the processes, down to the quantum level are not well understood when it comes to understanding why smoking kills. Your assumptions are bull.
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  18. rhjames: "If someone says that doubling CO@ might result in a 1 degC increase, then I'll accept that as consistent with known science. Anything beyond that is just guess work at this stage." Logically your comment is in error. Your own logic would imply that the 1 degree increase is guess work, because you know that there are feedbacks that would alter the forcings. You are defying your own logic by accepting what you call known science.
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  19. The Ville - we don't have to know why or how smoking kills - just that it increases the probability of contracting lung cancer etc. Just the increased frequency in a smoking population, after ruling out all other influences, is enough to take action. Climate statistics is still a long way from such certainty. In fact, it's a long way from any meaningful correlation with human activity.
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  20. The Ville - I don't know where you get your logic from. Doubling CO2 is expected to increase temperature by about 1 degC, based on direct "greenhouse" effects. This is based on good science, and is well accepted amongst climate scientists. Any further indirect increase is based on unsubstantiated assumptions of positive feedback dominating negative feedback, with no real data to back it up.
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