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Long Term Certainty

Posted on 18 August 2010 by Stephan Lewandowsky

Guest post by Stephan Lewandowsky

Who will win the AFL Grand Final in September?

No one knows, of course.

Human endeavours such as sports, markets, and marriages are notoriously difficult to predict.

Why, then, can climate scientists project global warming to the year 2100?

Part of the answer is that climate, unlike football, is a physical process. And physical processes can be predicted, sometimes with incredible accuracy. For example, the next total solar eclipse visible from Perth will be on the 31st of May 2068, and it will peak at 26.7 seconds past 11:54 local time. You can set your watch by that if you are still around in 58 years; the prediction is that accurate.

But if climate is a physical process that we can forecast, why can’t we now predict the weather during the Grand Final?

The answer is fascinating because it shows that short-term uncertainty can co-exist with long-term certainty. Suppose you visit the Burswood tonight and place a bet at roulette. Can anyone tell you what number is going to come up next?


Do you know what would happen if you kept betting for the next 10 years?


You’d lose a lot and the casino would win a lot. That’s why casino owners can sleep at night despite not being able to predict the next number at roulette—they can confidently expect to turn a handsome profit at the end of the year, which for the folks who own the Burswood was $280 million in 2009.

In much the same way we can be confident that the climate will be considerably warmer by 2100: That long-term virtual certainty is not affected by uncertainty about the weather during the Grand Final, in the same way that the Burswood’s profit is not affected by what happens during the next spin at the roulette table.

In confirmation, climate scientist Wally Broecker published a paper in 1975 that predicted the temperature rise by the end of the 20th century to within 1/10th of a degree. A quarter-century forecast that came within 1/10th of a degree! Today’s computer models are far more sophisticated and one would be ill-advised to ignore their forecasts for considerably more warming by the end of the century.

So is there no uncertainty about climate change?

There is uncertainty, but only in the way that there is uncertainty about what happens when you drive into a brick wall at 80 km/h. You might just get away with a few bruises and a concussion, but it is far more likely that you would break a leg or worse.

No one in their right mind would drive into a brick wall because the outcome is “uncertain.”

And no one in their right mind should delay action on climate change because we don’t know exactly how bad it is going to be. Whether it’ll be just bad or really bad or unbearably bad, we know that the climate is changing and that humans are causing it, with potentially serious consequences for us all.

So anyone who says that we shouldn’t act on climate change because of uncertainty is really inviting you to ride towards a brick wall at 80 km/h because it might not hurt. Are you feeling lucky? Or shouldn’t we better cut emissions in light of the uncertainty?

NOTE: this post is also being "climatecast" by Stephan Lewandowsky on RTR -FM 92.1 at 11.30 AM WAST today. It should air shortly after this post goes live so if you're reading this immediately (eg - you've subscribed to the SkS mailing list and just got this email), you can listen online via

This 3-minute podcast was previously “blog reviewed” here on Skeptical Science, and I wish to thank those who contributed to improving this piece through their thoughtful and detailed comments. For new readers, please bear in mind that the podcasts are spoken and hence must be understandable by listening alone—though obvious, this is no trivial matter because it mandates simplifications that would be unnecessary in writing.

For those who want to know more about short-term uncertainty and long-term forecasting, I recommend “Chaos: A very short introduction” by Lenny Smith (Oxford University Press).

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Comments 1 to 25:

  1. "And no one in their right mind should delay action on climate change because we don’t know exactly how bad it is going to be" This is not necassarily true. It would be a great mistake to restructure the world's economy and sources for fuels if climate change has relatively minor impacts. Restructuring economies based on long term projected benefits/negatives has been done before, with disastrous consequences (eg 1920s-1930s agriculture in Russia, 'Great leap Forward' in China). Partly because of these sort of historical precedents, a widespread and influential school of thought exists which rejects such large scale 'interferances' in eg market forces. Or alternatively, you have to do it from within the market system itself-which is what the whole carbon tax thing is about. Simply repeating 'its going to be bad' over and over is not going to have much affect on such thinking which has built up from mistakes made over the centuries, one needs to prop up the science and present the whole picture with regards to net risks and benefits, as well as providing viable alternatives, otherwise such a school of thought simply replies "we've heard it all before". As for your long term certainty, Burswood casino is rigged to benefit the casino, nature isn't 'rigged' to benefit anything, one way or another.
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  2. @thingadonta - I think nature is 'rigged' as far as climate is concerned, but we're doing the 'rigging' by dumping tens of billions of tons of CO2 into the atmosphere every year, and it probably wont be to anyone's benefit. And restructuring of our economies, particularly with regard to energy supply, is going to happen soon in any event - there's only so much oil to be drilled, and the 'cheap' resources are fast running out.
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  3. Thingadonta. "It would be a great mistake to restructure the world's economy and sources for fuels if climate change has relatively minor impacts." That might be true for a single, isolated issue (I can't think of a suitable parallel just now). But it certainly isn't for this one. Not only do we have this particular uncertainty about the consequences of burning fossil fuels, we have another one. There is equal uncertainty about how soon, how fast, those self-same fossil fuels will run out. Equally there is also uncertainty about how soon, how far, how fast the prices for these increasingly rare commodities will rise. And we do know, for a fact that they will be, one day - which day? - unaffordable for the general uses we now apply them to. So combining these uncertainties, we can address two (or three depending on your point of view) problems with a one-size-fits-all solution. This is an advantage, not a problem. We don't have to find several solutions, with the associated additional financing and reorganisation, to deal with several, simultaneous unrelated problems. Just one focused approach will deal with all the issues - including the effects on the oceans.
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  4. Stephan. Nice work. Good to see it come together so nicely.
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  5. Add one uncertainty with a substantial economic downside to a known and inevitable economic brick wall also with an extraordinary negative outcome and one could say we have a compelling case for change. It's a certainty that our supplies of liquid and gaseous hydrocarbons are going to buckle under the present demand curve, leading to fundamental inability to satisfy increasing consumption and thus inevitably escalating prices compounded by volatility. That's how our beloved market works, after all. It's safe to say that as far as petroleum and natural gas are concerned, they're a looming dead end for anybody wishing to preserve and extend our energy intensive lifestyle. For that matter there's huge spectrum of products touching every single aspect of our lives whose prices will balloon as we fecklessly burn hydrocarbons instead of using them more wisely. Does anybody think we're going to substitute coal for oil at the present rate of petroleum extraction and the type of applications satisfied by petroleum? Show some numbers. Exactly how is that going to work? Ignoring this is a good prescription for willingly abandoning overall economic prosperity but for some unfathomable reason it's become a standard part of the climate contrarian mantra, as demonstrated by Thingadonta. So, taking the contrarians' advice we're going to see our mobility massively impaired as we return to the age of coal. We'll be making polymers and fuel from increasingly lousy, dirt-saturated sub-bituminous fossil plants. That's it, the best we can do because we're so scared of facing the future, frightened by demagogues conjuring ghosts of failed totalitarian regimes? Now that's depressing. Surely we can do better.
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  6. Well the AFL Grand final will be won by one of sixteen clubs (probably less by now). And most likely will be won by St Kilda, Geelong or the Magpies. While it can't be predicted with 100% certainty now there are very few realistic outcomes. In comparison the climate is far more complex and chaotic. To keep the footy analogy we don't actually know how many teams are playing. And even some of the teams we know about we have absolutely no idea about their form. Even supposedly the most important player on the field, CO2, is far from completely understood. It is as you say a simple matter of understanding a not infinite number of physical processes (that's true about everything), problem is we don't have that understanding yet. Just on the Wally Broecker prediction. How many temperature estimates have been published over the past 3 decades? My guess is many and most are far less accurate than that. Hansen 1988 might be one example. I'm saying we shouldn’t act on climate change because of uncertainty but I'm with you in not recommending the brick wall at 80mph thing.
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  7. No one in their right mind would drive into a brick wall because the outcome is “uncertain.” Yes, but no one in their right mind would drive into a ravine to avoid the brick wall. Also because cars are designed to help passengers withstand some kind of impacts, but not others. It would be ironic to see the world embark into another Titanic moment a hundred years after the original tragedy, steering away at the wrong moment and therefore ruining any chance of survival.
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    Moderator Response: I am intrigued by the various degrees of alarmism raised to counter my suggestion that people would be ill-advised to drive into a brick wall. I agree, if avoiding the wall meant driving into a ravine, then the choice would be challenging indeed. However, this is not the choice we have to make. There are clear precedents that it is possible to slow down while being paid to do so: Denmark cut carbon emissions by 21% between 1990 and 2006 while at the same time increasing its GDP by a whopping 44%, and Germany reduced carbon emissions by 28% whilst increasing GDP by 32% and creating more than 300,000 clean-energy jobs at the same time. Lest you think only Europeans can be that smart, the Australian CSIRO released a study recently which indicated that some 3 million jobs could be created during a 20-year transition to a low-carbon economy. So, there is no imaginary ravine. The choice is between hitting a brick wall and the economic *REWARDS* associated with slowing down and avoiding the impact. SL
  8. I am wondering why the said eclipse is being predicted as being visible from Perth. As has happened many times in the past cloud cover has obscured, or partly obscured such events around the world. If of course the cloud cover for that particular point of time is also able to be predicted with the same degree of accuracy as the movement of the planets, then the claim that the eclipse will indeed be visible may be justified. However for that particular period of any year, May/June, the likelihood of thick cloud cover is quite high. Perhaps being able to predict the winner of the grand final would be far more realistic than being able to predict cloud coverage so far out especially given the poor current understanding of what are all the drivers of cloud processes.
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  9. @6 - Mmmmm, there are a lot of problems with that outlook.
    While it can't be predicted with 100% certainty now there are very few realistic outcomes.
    Indeed. Same goes for rising temperatures over short geologic timescales which have no other rational explanation other than increasing greenhouse gas concentrations. Realistic outcomes include "moderately bad", "really bad", and "holy crap that's bad". The problem is that all 7 billion of us haven't experienced such rapid change before, and we're pretty fixed in our ways. Our agriculture production, our beachfront cities, etc etc. It doesn't take much (as you can see from even temporary drought effects, etc) to throw things into relative chaos, and we historically do not seem to adjust well.
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  10. I have seen predictions of warming up to 2100AD, with increases of between 2 and 5 degrees, depending on the scenario. However, these graphs show the temperature continuing to rise steadily at the end of this period. What will happen in the next thousand years? I cannot find much info about when or how high the maximum will eventually be. Does anyone have any info about the long-term?
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  11. johnd Cloud cover in Perth - any month of the year? Having spent a bit of time there on business a few years ago, during what passes for winter in Perth, I'd be reasonably confident of it being clear. Only once I arrived during a horrendous storm, on the other occasions I left my coat, gloves and other winter type paraphernalia in my room every single day. Apart from the winds off the beach at Freo, all was mild and warm.
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  12. Another analogy might be smoking. I recall being struck by a number of friends who were light smokers (not even daily smokers, reasonably fit, and hence presumably at 'mild risk') who had coronary events in their mid-forties. Now smoking that one cigarette probably does you very little harm. However, each cigarette carries a cumulative risk of a range of well-documented adverse events. Interestingly, a heavy smoker's chances of having a heart attack fall by about 50% within eight hours of their last cigarette! Then again, every heavy smoker or drink has a grandfather/ uncle/ significant other (usually male) who smoked 40 cigarettes a day and half a bottle of whisky a day and lived till the age of 90. Probabilities and how we behave in response to them are fascinating. There's a vast body of evidence that people do not respond logically to probabilities but rather to perceptions. Consequently, people will respond differently to scenarios which carry identical risks/benefits depending on presentation much to the despair of economists, game theorists, and other practitioners of the dark arts.
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  13. Pikaia, as we go further out the total amount of fossil fuels we will end up burning and long term climate feedback effects play a bigger and bigger role... making the eventual maximum highly uncertain. Even the rate at which we burn fuels would play a significant part as the oceans could absorb most of the extra CO2 if given enough time to disperse it rather than the ocean surface always being saturated. That said, I recall a worst case scenario study in New Scientist based on burning all available fossil fuels coming out to about 13 C by 3000 AD. Sticking just to known conventional reserves would top out around 7 C. Since then Canada has gone big into tar sands and deepwater drilling is becoming commonplace... so we're looking at exceeding 'conventional reserves' unless things change.
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  14. About Moderator´s response at #7: I have also noticed this "alarmism against mitigation" here and there. For those, any change in the climate is manageble, even if science shows it´s probably unprecedented in human history. Any interference in the use of fossil fuels, on the other hand, is doom - even if phased out in the pace of generations.
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  15. Are the available climate models able to take the "present state" and based on this calculate backward in time to say 1800 and replicate the record we have?
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  16. E-e-e-e-e-ek!!! "shouldn’t we better cut emissions"? Do they really speak English that way Down Under?? "Hadn't we better cut emissions" would be immediately understood as correct over here.
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    Moderator Response: G'donyamate for picking that. My apologies. SL
  17. about SL's moderator response to #7 I thought everybody agreed that all efforts implemented so far, and especially the European ones, were too little, too slow, too late and too much of a whited sepulchre to be taken as example of what serious mitigation would look like... usually one is presented with a choice between climate catastrophe and the wholesale redesign of the economy... that's why I for one am much more interested in adaptation
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  18. Adaptation: "Cabin pressure may change." Nice words, hiding a myriad of nasty details. Useful for feeling good.
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  19. Can it be proven we can not adapt?
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  20. "I am intrigued by the various degrees of alarmism raised to counter my suggestion that people would be ill-advised to drive into a brick wall." This kind of argument has been in use, in many version, for thousand of years in our culture and the only reason people submitted to it is because there has been no relasitic alternative until around mid 19'th century. When this argument comes around in a new modern envelope it should not be surprised it will face high resistance in those cultures.
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  21. The claim that football is not a "physical process" is strange. What is it, then? This could be reworded to convey the same idea ("human behavior is very hard to predict")while not annoying materialists like myself.
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  22. Since this discussion has touched on oil/coal curves and energy related issues, a few points: -The world has at least 30-50 years of conventional oil, even at enhanced consumption rates. It has many times more than this of 'unconventional' oil shale and tar sands, however there are problems with rate of extraction of such. One estimate is that there are 242 times as much oil in remaining tar sands and oil shales than in all the oil which has already been consumed in conventional oil sources. -Many of these tar sands and oil shales are not currently being extracted because it is simply more economic to keep using conventional oil and gas. -Venezuela and Canada both have far more remaining oil in tar sands and oil shale than all the oil that has been produced in the Middle East. Canada recently annouced that it has more economically recoverable oil in tar sands, based on current prices, than Saudi Arabia has in conventional oil. -The USA also has vast resources of oil shale (eg inb Wyoming), enough to supply its own domestic needs for over a century, however at current oil prices these are not economic. Of course, extraction and access to these resources are also being blocked to some extent by green -driven agendas. -The world isnt going to run out of oil, any more than the Stone Age ran out of stones, it will simply move on to something else, when they become more economic. So far various renewables arent competitive. -It seems strange to me that so many who support strong AGW also support renewable energies being economically viable. One doesnt necassarily follow from the other, so this suggests a pattern-bias. AGW can have bad consequences, this doesn't mean renewable energies currently/will work at large scales. -Switching to renewable energies will 'create jobs', but at a higher cost to consumers and the taxpayer. Many such jobs are actually subsidised, by the taxpayer or otherwise. Many green groups have a hard time understanding this, becuase their jobs are also subsidised, they dont pay for themselves- they rely on society's good will to exist. This generally doesnt happen in oil and coal. -Renewable energies are currently largely an artificial market, suported on the belief that eventually they will become economic, when they currently are not. Such is probably the case for Denmark and Germany, and Spain. -One renewable energy which ha hogh potential in Australia is hot rocks. With Australia's low population and high radioactive granties close to the surface, this has the potential to be economically viable on a large scale. Currently however, hot rock technology is heavily subsidised by thre taxpayer. All such jobs are currently 'superficial'. -Australia, in any case is in a different position to Europe. Australia has a low population relative to energy-intensive exports, so obviously has a high carbon emission per capita. This is unlikely to change. Australia's GDP is largely dependant on the economic base of adjacent Asia, and exports which involve highly localised, captital and energy intensive industry drive up carbon emissions/capita. This won't change as long as Aisi continues to grow, whether we introduce wave and wind energy or not. -Australia currently has at least 400 years of mineable coal at current extraction rates. We import most oil and gas, however there is potentially large resources of oil shale, which is also being blocked by green-driven agendas (much like in the USA, although Venzeuala's totalitarian socialist government has one advantage-it can ignroe green driven agendas if it feels like it). We aren't going to 'run out' of oil quickly, but alternatives may become economic if rate of extraction of tar sands and oil shales remains an issue. But these 'alternative' energy source can only be subsidised for so long, they will need to economic at large scales on their own if they are to be competitive, which most at the present time are not, particularly at large scales (eg hot rocks).
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  23. Thingadonta points out that prices for fossil fuels-- particularly liquids-- will become uncompetitive w/newer and more modern energy capture and liberation systems as we're forced to use increasingly poor and economically defective deposits, moving from flowing crude through tar and finally to hydrocarbons finely dispersed and tightly locked in shale. The variety of "green" to end our brief and sadly temporary fling with virtually free energy will be of the folding kind, not the two-legged sort.
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  24. thingadonta wrote : "Switching to renewable energies will 'create jobs', but at a higher cost to consumers and the taxpayer. Many such jobs are actually subsidised, by the taxpayer or otherwise. Many green groups have a hard time understanding this, becuase their jobs are also subsidised, they dont pay for themselves- they rely on society's good will to exist. This generally doesnt happen in oil and coal." Certainly not in America, judging by these reports : Energy Subsidies and Support by Type and Fuel (million 2007dollars) Coal/Refined Coal/Natural Gas/Petroleum Liquids - 5451 Nuclear - 1267 Renewables - 4875 Subsidy and Support per Unit of Production (dollars/megawatthour) Coal - 0.44 Refined Coal - 29.81 Natural Gas & Petroleum Liquids - 0.25 Nuclear - 1.59 Solar - 24.34 Wind - 23.37 "For example, even though coal receives more subsidies in absolute terms than wind power, the use of wind is likely to be more dependent on the availability of subsidies than the use of coal." Federal Financial Interventions and Subsidies in Energy Markets 2007 The largest U.S subsidies to fossil fuels are attributed to tax breaks that aid foreign oil production, according to research released by ELI. The study, which reviewed fossil fuel and energy subsidies for Fiscal Years 2002-2008, reveals that the lion’s share of energy subsidies supported energy sources that emit high levels of greenhouse gases. Fossil fuels benefited from approximately $72 billion over the seven-year period, while subsidies for renewable fuels totaled only $29 billion. Estimating U.S. Government Subsidies to Energy Sources: 2002-2008 Do you have actual figures and evidence that you can link to that goes against the above ?
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  25. JMurphy, you're forgetting about the forced subsidy we'll be paying to the fossil fuels industry in upcoming years. Estimates on those future payments range from $890 trillion to $1240 trillion, depending on how much we want to comply with industry desire for us to pretend that paying for their products ends when fuel is delivered and money is handed over. Assessing the costs of adaptation to climate change Waffling about making decisions might be considered another gift. The top eight petroleum extraction, refining and marketing firms enjoy something like $2.2 trillion per year of revenue for each year we choose to help them continue thriving. That revenue could be dialed back even as we conserve petroleum products for better uses and simultaneously shrink the subsidy of adaptation we'll be making to those firms in future years. What's really annoying in the case of the petroleum industry is that the adaptation subsidy will continue long after they're unable to deliver useful quantities of their product. What a deal for them, eh?
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