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Is it safe to double atmospheric Carbon Dioxide over a 200 year period?

Posted on 24 December 2010 by fingerprinter

We are on track to double pre-industrial atmospheric carbon dioxide concentrations. In assessing the risk, the above question is much more fundamental than asking how much the climate warmed over the 20th century. So what’s the answer?

Society has standard approaches for assessing risk and safety. When it comes to assessing risk for major intervention, this approach entails a null hypothesis, or base assumption, that things are unsafe until proven safe.  Examples occur in medicine, engineering and just about every human activity. In medicine, a drug company can not assume that a new vaccine is safe, with the burden of proof on others to prove it is unsafe. Note that this is different to determining whether the vaccine is effective, where the null hypothesis could be that there is no association between the vaccine and immunity. Rather, the null hypothesis for the risk assessment relates to the question, can I use this vaccine for a major public vaccination program?

When it comes to carbon pollution, the normal convention for risk assessment goes right out the window. The scientific null hypothesis that there is no association between carbon dioxide and climate change is easily broken. But the public risk question really relates to doubling the atmospheric carbon dioxide concentration in 200 years. In other words, is altering atmospheric chemistry in that manner safe?  In the weird world of greenhouse policy, we would like everyone to assume that putting 3.6 billion tons of carbon into the atmosphere is entirely safe, with the onus on climatologists to prove otherwise.

Taking the wrong null hypothesis has serious implications for the way the science is assessed. Going back to our medical analogy, even a relatively small amount of evidence that the vaccine is unsafe is enough to inform a risk assessment. In other words, the null hypothesis stands. You need to produce a great deal of evidence to satisfy authorities that the vaccine is safe.

In the assessment of carbon pollution, we have this the wrong way around. Small uncertainties in the conventional science are used to reinforce the notion that doubling atmospheric carbon dioxide is entirely safe. Most importantly, and somewhat amazingly when you stop to think about it, major polluters and proponents of continued carbon pollution have never proved that their product is safe. Not only that, they haven’t even been asked, by governments and the public alike, to prove that their product is safe.

This means that, to date, we have no studies demonstrating that the climate system is insensitive to such increases in carbon dioxide, and a mountain of evidence indicating that doubling atmospheric carbon dioxide will result in dramatic climate change. Yet still, we refuse to really accept the risks. One of the biggest reasons for this is that the skeptics have been successful in limiting public discussion to 20th century global mean temperature. In reality, the case against doubling atmospheric carbon dioxide is well established before we look at the 20th century climate record.

One of the most certain things in climate science is that increasing carbon dioxide warms the climate system. Doubling atmospheric concentrations is sure to cause significant warming of the climate system. And doubling a over a 200 year period represents one of the most rapid changes in atmospheric carbon dioxide in the history of the Earth.

The certainty that carbon dioxide warms the climate system does not rely on any 20th century climate observations, such as employed in fingerprinting studies. These studies seek to determine how much the 40% increase in carbon dioxide over the 20th century has already affected the climate. Rather, the evidence against increasing carbon dioxide is much more fundamental.

The first place to look is of course the paleoclimate record. Over the last several decades of research, the sensitivity of the climate system to changes in carbon dioxide has been established through ice core samples and other proxy climate indicators. In short, past climates with high atmospheric carbon dioxide concentrations were very warm, unless incoming solar radiation was low. Rapid changes in carbon dioxide (such as due to planetary volcanic activity or asteroid strikes) resulted in rapid changes in the climate system. The literature on this topic remains unchallenged; in the Earth’s geological history, if carbon dioxide concentrations increased, the planet warmed.

The second and more important place to look is the fundamental physics and chemistry- using mathematical modelling. Models used in climate come in different shapes and sizes. Some of the most basic models, such as the behaviour of gases exposed to radiation of different wavelengths, are well established physical models.

Far from being controversial, numerical models are used in all modern fields of science. Mathematical models are implicit in our understanding of the universe. For example, the governing equation for the gravitational effect is also 'just a model'.  In fact, it’s the very definition of a model, since we do not actually understand how gravity works. However our mathematical model of the nature of gravity has been verified through countless observations. We are quite certain that our mathematical model of gravity accurately describes the Newtonian universe. These principles are not negotiable like the tenets of social sciences or economics. They are fundamental laws. The universe doesn't fudge fundamental laws of scale.

Similarly, the mathematical model of the organisation of an atom; neutrons, protons, electrons, is just a model. We cannot actually look inside an atom. But the model has been verified and it holds as a fundamental certainty.

The mathematical model of how atoms absorb and re-emit radiation in discrete energy packets and in discrete wavelengths is also a model. It also faithfully describes the universe. A whole heap of technology is built on the certainty of this model. If these models did not work, then most of the appliances in your house would also not work, including the microwave oven and the television.

Therefore we can faithfully model how radiation passing through layers of radiative gas will be absorbed and re-emitted. There is nothing speculative about this either. This is fundamental physics and chemistry, text book material rather than brand new science.


(Image created by Robert A. Rohde / Global Warming Art)

If anyone seriously thinks that our understanding of radiation is wrong, then could they please publish that alternative theory in a proper scientific journal so we can all absorb a new reality? You will need to overturn more than 100 years of physics in the process. You will also likely win a Nobel Prize for your efforts. The incentive is there.

You see, you can't just say you don't agree with the fundamental laws of physics, or that you are not convinced by them, and leave it at that. At least, not if you want to be taken seriously in the scientific community (as opposed to simply confusing the public with red herrings). As an aside, I suspect that being taken seriously by the science community has never been a key priority for the skeptics.  By publishing almost exclusively on blogs and in the opinion sections of newspapers, and eschewing peer-reviewed scientific journals, they have staked out their real audience. Contributing to science has nothing to do with it.

Now where were we? Oh yes, we understand entirely how radiative gases like carbon dioxide absorb and re-emit radiation from physics, quantum physics and chemistry. We also understand the physics of radiation (for example the Stephan Boltzmann relationship). We understand entirely that if you increase the concentrations of carbon dioxide in the atmosphere, you will warm the surface of the planet. This result is repeatable (you get the same answer) using a simple model of radiation physics alone (just a couple of lines of code) or using a fully coupled atmosphere-ocean-sea-ice model with turbulent mixing. People have been trying to break this result for fifty years and have not. That’s how science works.

The sensitivity of the atmosphere to greenhouse gases can also be observed on nearby planets (Mars and Venus) and is consistent with the maths. The maths is also supported by the observed feedback mechanism between temperature and carbon dioxide in the ice-core record and other paleo indicators. If you double or even triple atmospheric carbon dioxide, which we will do sometime this century or early next, you will significantly warm the climate system. This is well above a 95% probability, and is hence a near certainty. No one has disproved any of this in the literature. No drug would make it onto the market with that kind of evidence running against it.

The climate system is complex, so the fundamental physics operates over many interacting variables. As such, many things can act to slow down the rate of warming or amplify it, such as the warming-water vapour feedback mechanism. But the system is not that complex, and is certainly far less complex than the human body. And the complexity of the system cannot change the radiative properties of carbon dioxide. Hence, over time, and given the rate of carbon dioxide increases that are proposed, warming will be set in train and is assured from the fundamental physics. Hence we are certain from all the science that the mean trajectory we are now on is a warming trajectory. Small uncertainties in the rate of future warming are irrelevant to the risk assessment. That’s like pinning the risk assessment associated with childhood exposure to UV radiation to uncertainty in the exact age that skin cancer is most likely to occur.

The climate of the deep past has shown that we are nowhere near the natural limits of warming for planet Earth. In other words, the current state of the climate has more things that can amplify warming than it does things that will keep a lid on the warming. There are mechanisms that limit warming, but we have plenty of room to warm given that the level of pre-industrial carbon dioxide was very low in relation to extremely warm climates in the distant past. This level of warming is more than enough to elevate sea level and change the predominant patterns of global climate. The uncertainties in the context of the enhanced greenhouse effect are actually more worrying than they are reassuring. This is a concept that the public does not understand very well.

Guess what? I haven’t even talked about a 20th century thermometer reading, and we already have heaps of evidence against the safety of rapidly doubling atmospheric carbon dioxide. The matching greenhouse fingerprints in the 20th century climate record are really the final nail of evidence.  If there is some study that contradicts the fundamental science, then where is it? No one has managed to find an alternative solution after decades of trying. While the skeptics will throw up the occasional vaguely set-out paper from fringe (and mostly non peer-reviewed) journals, they can not produce a set of key papers which demonstrate that doubling atmospheric chemistry has no significant effect on the climate system. And that is what they wish to prove is it not? It is certainly what they should be required to do.

So people should ask the skeptics their own set of questions. Why have they never produced a repeatable formulation of the physics as they see it? Why have they never developed their own climate models, and performed their own model experiments? Why have they never produced their own paleoclimate reconstructions? Why have they never compiled their own record of surface temperature?  Apparently, the lack of published research showing the inert nature of atmospheric carbon dioxide changes is the result of a long running, worldwide scientific conspiracy.

But that too doesn't stand up. With all the money supposedly at stake, the complete lack of credible research by the skeptics points to a complete inability to successfully argue their case in scientific circles. If destroying the conventional science was as easy as they suggest, the major polluters would have funded such research twenty years ago, and moved on. Again, the incentive is there, and large companies are more than capable of funding and producing credible research. But, importantly, they have not attempted to do so.

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Comments 1 to 50 out of 109:

  1. Not true- Food is not proven to be safe yet we eat it (where are the studies) No food for scientists. Are we going to stop everything going into atmosphere because no studies have proven that its safe. With dynamic systems you can't stop everything and wait for the studies the beginning position is so difficult to pick. You have no scientific credibility. You will have to be covered in a hermetic sealed container until the studies are done.
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  2. The first part of cloa513's assertion is correct. There are other facets of our lives where we seem to shoot first and ask questions later: food, banking, wars - all spring to mind. So, sadly, dumping crap in the environment without nary a concern for the effects is by no means unique. The second half, however, is incorrect. Now that we have done the deed, the studies have been done, the data has been collected and the evidence is overwhelming.
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  3. Is it safe to double atmospheric Carbon Dioxide over a 200 year period?"

    A resounding "No!". Why are we humans so myopic? The events occurring right now (well for several years now) on the planet are evidence that tinkering with the the planet's energy budget and oceans (i.e., ocean acidification) is just not a good idea. There are warning signs everywhere, why do some insist on continuing to ignore them?
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  4. For the record. I was not stating that we historically or currently test everything we do. I am simply stating that when we do seek to apply a scientific risk assessment, there is an established methodology for doing that. We rely on this standard methodology more than people immediately imagine.

    Happy holidays.
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  5. “Faulty Forecasting Procedures” - incorrect assessment of the risks of global warming - is a fundamental objection - skeptics - to the theory of AGW proponents. About this - not the climate - for example, often says economics professor Vaclav Klaus.

    You may not like: J. Scott Armstrong, Kesten C. Green and Willie Soon ..., but they have excellent academic achievements - an important peer-reviewed publications.
    So why did they write in their report (May 4, 2010.)?:
    - “Most of our findings have been published in the peer-reviewed literature and all have been presented at scientific meetings.”
    - „The alarming forecasts of dangerous manmade global warming are not the product of proper scientific evidence-based forecasting methods.”
    - “As with many conclusions from scientific research on forecasting, this conclusion derives from a finding that is not intuitive: in complex situations with high uncertainty, one should use methods that are conservative and simple (Armstrong 1985; Armstrong 2001).”
    - “The forecasting procedures described in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report violated 81% of the 89 principles relevant to climate forecasting.”

    Atte Korhola, author important peer-reviewed paper about past climate: “Decision-makers should make sensible choices regarding the overall benefits in the environment of uncertainty. We shouldn't expect anything magical from the climate change panel that it is incapable of producing.”
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  6. Arkadiusz is misusing "peer-reviewed" as if it conferred some sort of infallibility on the authors's conclusions. Far from it. On the contrary: every "peer-reviewed" paper he cites is proof of how flawed the peer review system has become.

    For despite the skeptic's regular rants, there really is no logical denial of the conclusion: AGW is a serious problem, we must cut greenhouse gases immediately to avoid catastrophe.
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  7. The author of this article is using "null hypothesis" in a surprising sense. I am much more used to seeing it used in a somewhat different sense, as in http://en.wikipedia.org/wiki/Null_hypothesis.

    So is the author's sense an acceptable one, or is he misusing the term?
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  8. Sorry - I give the current link: May 4, 2010.
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  9. @MattJ

    „we must” - very good - all right - but on the proper methods of risk prediction ...
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  10. I think the problem you have is that you are trying to get people to change their whole way of life, and companies to worry about other things than their profitability. The governments of countries to carry out unpopular things. I don't think you have much chance until it is too late and the world is burning up or drowning.

    Here in the UK we are having a very unusally cold winter which will undermine your attempts to convince ordinary people that there is a problem. Hot dry summers here are longed for.
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  11. kdfv
    that's a real risk, the typical situation of a tragedy of the commons. Avoiding the unpleasant outcomes of a warmer planet stands on the ability of our societies to look beyond their backyard and further away; which, by itself, I'd dare to call a cultural revolution.
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  12. fingerprinter:
    "So people should ask the skeptics their own set of questions...
    Why have they never developed their own climate models, and performed their own model experiments?"

    ABSOLUTELY!

    Where is the science, fullstop.

    Most of them seem to depend more on myth, rumour and political intrigue than any rational thought.
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  13. I don't understand why anyone is still denying climate change and global warming. Where I live there are an increasing number of extreme weather events signifying global warming. Record long hot drought with record bushfires, followed by record rain events with widespread flooding. From what I read, record (ie extreme) weather events are happening more and more frequently around the world with serious consequences for food production, housing and travel. And this is just the start of the global warming.

    If people can't recognise it's happening now, what on earth will it take? Will they be still denying it when the extreme events get worse as they will as the earth warms, if we don't do enough soon enough to curb emissions?
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  14. I have to disagree with the base assertion that all things are considered unsafe until proven safe. Nothing is 'safe'. Getting out of bed in the morning is (so we are told) the most risky thing you can do. Everything we do has some kind of risk attached to it and thus nothing is 'safe'
    Risk assessment is just that - making an objective assessment of the risk and then deciding whether the benefits derived are sufficient to warrant taking the risk. Thalidomide was considered 'safe'. Cars are definitely 'not safe' in many ways. Potholing/sailing/sex/alcohol are full of risk. ( I don't do any of them...well, maybe one)
    Life is about risk management, not risk avoidance regardless of the cost - the Nanny State Syndrome.
    Is it safe to double CO2 concentrations over a 200yr period is an unanswerable question - we simply do not have the means to accurately predict the effect on climate, but we can predict the effect of reducing FF . Modern society, like it or not, relies heavily on cheap electricity generation so maybe the question ought to be - what are the risks if we restrict FF usage without first having economically viable alternatives ??
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  15. Original Post

    The general point that skeptics must offer alternative models and research is bogus.

    Pointing out inconsistencies and weaknesses in AGW science - does not oblige the critic to offer a whole new theory.

    It does oblige the purveyors of the AGW theory to explain the inconsistencies if they are to be taken seriously.

    Here are a few 'inconsistencies' to consider:

    Deep mixing of the ocean layers is inconsistent with suface layer acidification.

    Flat or slight increase in OHC content from Argo is inconsistent with a steady or increasing TOA forcing imbalance.

    The mix of SLR (steric and mass) is inconsistent with the energy balance.

    Three more important 'inconsistencies' I cannot contemplate.
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  16. Ken Lambert @15

    You're right. But contrarians need to understand that pointing out aspects which are not yet properly understood does not mean that the theory is invalid or that the scientists cannot be taken seriously. It simply means that, as in any scientific theory, more work needs to be done.
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  17. As far as the planet itself the answer is yes as the planet's relentless geological march will correct our mistakes over time (most likely long after we disappear). Whether it might be safe or not for the wellbeing of humans and other biota is another matter all together. Some here might even live long enough to witness first hand which side of the issue is correct. I know I have.
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  18. I have to say that if getting out of bed in the morning is the most risky thing that some people do (re #15 Mizimi), it's no wonder they are so paralysed with fear of global warming that they flat out refuse to accept it :)

    And science can tell us in broad terms the likely effect of doubling C02 over a short period by looking at the past. It would be a hot and rocky ride! It's bad enough increasing CO2 by 44%, as everyone should have noticed by now.

    And there are economically viable alternatives to fossil fuel for energy. Initially some renewable energy is costing a bit more in dollar terms, but as time goes on the cost reduces so that in a short while it will cost much less than dirty energy. Certainly a lot cheaper than trying to live in a world with climate disasters.

    How many people only ever buy the cheapest of everything, especially when the cheapest product is so much more harmful? If that were the case we'd still be driving with leaded petrol. No-one would ever buy a car with safety features. (No-one would have a car at all - horses and buggies were cheaper.) Organic food would not be fashionable. etc etc
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  19. Correction - my reference was to #14, not #15.
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  20. cloa513 @ 1... Just last night we had a prime example of how you are wrong about food. My family went for a walk in the local park after a long week of rain. We found tons of mushrooms everywhere. A couple of large ones I picked looked particularly interesting and I thought might be edible. I came home and tried to look them up. None looked exactly like what I picked so we opted to throw them away. I also had emailed a friend who is knowledgeable. He wrote me back this morning to say they looked like they might be part of the amanita family, likely very deadly.

    My assumption, in the face of an unknown, absolutely HAD to be that the mushrooms were unsafe until proven safe.

    Your food analogy is wrong because you are comparing risk factors that are not equal. Food as you purchase it in the store has already been through a risk proposition many times over. You are not eating completely unknown foods. You are eating foods that are known to be safe. There still is a very tiny element of risk but the risk is so small as to not be of concern.
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  21. So, in your view of applied science we must test every bridge to destruction before we build it.

    We must switch from coal to nuclear, because the former may be dangerous but the latter is perfectly safe (Chernobyl, Three Mile island, irradiated fuel storage, plutonium proliferation).

    We must rely on renewable energy, whatever the resulting energy shortage does to the developing world. And we must stop the industrial revolutions in China and India because their cheap and abundant energy is dangerous. And we must persuade America to go back 100 years and give up air conditioning

    You call for a sceptical experiment. One is underway. It is universally accepted that, if increasing CO2 has any effect on climate, it is logarithmic. In other words it is the early increments that matter most.

    Starting at 280 ppm, 395ppm of CO2 will do more than half of whatever it is that doubling pre-industrial CO2 will do. Look at your own temperature charts. Starting from the depths of the Little Ice Age (to where they had fallen from the Medieval Warm period), temperatures peaked in 1940. From there, during a period of maximum CO2 potency, they have risen at a rate of 0.64degrees C per century, and currently show every indication of slowing down. Nothing to worry about so far.

    Science (and engineering) works on established theory and practice, while keeping a wary eye open for contrary indicators. Nothing is better established than basic thermodynamics. If we can clear up the confusion between heat and energy that permeates popular AGW theory we would eliminate 90% of the current theories (there are many more than one).

    All we need for a simple demonstration is to accept that the ability of energy to do anything – raise temperatures or produce work – depends on its surroundings. Heat is the ability to do these things. It is, by definition, the net energy transfer between regions at two different temperatures, from the higher to the lower. It is uni-directional, and depends on a function of the temperature difference, ie f(T2 –T1).

    For radiative energy it is actually a function of the difference between the fourth powers of the temperature, but we can ignore that qualification for the sake of this argument.

    Consider a bare earth heated by incoming energy from the sun and radiating W watts per square meter into space. T1 s zero, so the radiated energy, W = f(T2).

    Now surround the pare earth with an absorptive layer of gas which permits the incoming energy to continue to heat the earth, and which absorbs all the outgoing energy. The atmospheric layer must now radiate W to space, and must rise to a temperature T2 in order to do so.

    Butt he earth must radiate W to the atmosphere, and to do so its temperature must increase to T3 so that W = f(T3 – T2).

    Now what will happen if the absorptivity of the atmosphere increases again? Nothing will happen. If the atmospheric temperature increased, the outgoing energy to space would be greater than the incoming energy, and it would promptly cool down again.

    The trick here (to use a climate science term) is that once all the energy from the earth is being absorbed, further absorptivity will make no difference to the temperatures.

    This saturation effect was demonstrated in the laboratory by Angstrom (he of the unit) 100 years ago. You can see it again here: http://www.espere.net/Unitedkingdom/water/uk_overview.htm

    And for anyone who wishes to identify back energy radiation in this model from atmosphere to earth, it is the negative term in the heat transfer equation.
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  22. Ken Lambert @15... Regarding inconsistencies in AGW theory. Yes, there are aspects of AGW that are not yet explained. There are aspects of gravitational theory that are not explained. Vast parts of the big bang theory can not yet be explained. But each of these are accepted because the preponderance of evidence shows they are most likely accurate representations of reality.

    Small unexplained elements of a theory do not undermine a theory. In order to prove a theory wrong you need to have a competing theory that fully explains all current observations. And it needs to explain them BETTER.
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  23. Very good article. I'd been thinking about writing one on the risk assessment perspective myself, but you beat me to it, and probably did a better job than I would have.

    In the environmental field, we don't mess around with risk. If there is even a chance that a chemical is carcinogenic, we regulate it. We don't say "oh well there are some uncertainties, it causes cancer at high doses in some animals, but maybe it's fine in humans, so we'll just keep releasing it into the environment and see what happens." But that is the global warming 'skeptic' approach. They want to just wait and see what happens because there is uncertainty. There will always be uncertainty, but from a risk assessment standpoint, you don't mess around with public health. You err on the side of caution every time. But that's not what we do with the climate.

    Rob Honeycutt @ #20 is also correct. In the USA we have the FDA which ensures that the food we consume is safe. When unsafe food gets through, it's a major scandal. Most of us don't just go out into the woods and eat whatever mushrooms or berries we find in the hopes that they won't kill us. In most cases we err on the side of caution to protect public health. On the climate, we're failing miserably to protect our health in the same manner. From a risk assessment standpoint, it's really quite appalling.
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  24. Vast majority of climate 'skeptism' has nothing to do with science or evidence. More information or analysis will not help. It is a culture war waged by those adopting neo-conservative values and whose very identity and world view is threatened by the reality of climate change. As Clive Hamilton puts it: "facts quail before beliefs".

    Everyone should consider this point he makes in his excellent essay Why We Resist the Truth About Climate Change

    "The evidence contradicting the information deficit model is overwhelming, so that those who
    continue to cleave to it, ipso facto, demonstrate its falsity. Faith in the power of information prevails
    over the power of information."

    We are not the rational creatures we'd like to think we are.
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  25. "So, in your view of applied science we must test every bridge to destruction before we build it."

    Strangely enough, that's exactly what's done to bridge components, not to mention every new major airline design (the Boeing 787 project has suffered many delays, one was due to a destruction test showing that stressing the wings caused a failure in the connection to the fuselage at a level of force less than predicted by engineers).

    A quick read of the rest of your post shows a similar lack of understanding of stuff you talk about. Saturation doesn't not happen in the atmosphere, and the physics showing why Angstrom (who perhaps should've stuck to his unit) was wrong was figured out over FIFTY YEARS AGO.
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    Moderator Response: Don't use all caps.
  26. Clarification - Angstrom wasn't wrong in the context of the experiment he performed, he was wrong in his extrapolation of that experiment to the atmosphere.

    Here's a summary of the physics involved:

    http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument/
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  27. #20 Rob

    Maple Leaf Foods which has been in business for well over 100 years had a major problem with listeriosis in it's packaged meats in mid 2008 which led to several deaths. Any resulting deaths place such issues far from a tiny risk factor or little concern. I would submit that your food may not be as safe as you might think.

    Some of you that live in the U.S. might think that the USDA and FDA have your best interests at heart (and they do, but are constrained by the lack of technology). You might be surprised upon closer scrutiny as to just how much tainted stuff is let through. There is a relatively good elementary article on this subject here.
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  28. Fred Staples said:

    Now what will happen if the absorptivity of the atmosphere increases again? Nothing will happen. If the atmospheric temperature increased, the outgoing energy to space would be greater than the incoming energy, and it would promptly cool down again.

    OK, what part of the atmosphere radiates IR directly to space? And as the CO2 concentration increases, what happens to that part of the atmosphere? How will that impact the average temperature at the Earth's surface, and why? If you have even a *very basic* understanding of atmospheric physics, these should be slam-dunk easy questions for you to answer
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  29. Long before we had modern science, one of the ways we know whether food was safe was by watching what happened to our neighbour when they ate those tempting red berries. If only we had a neighbouring planet that had quickly consumed all its coal deposits; then we wouldn't need all those GCMs, we could disband the IPCC and James Hansen could spend more time with his grandchildren.

    Those red berries tasted nice, perhaps the fever that I'm starting to experience means that I should just eat more of them. Um, why are those alien neighbours watching me so closely?
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  30. #21: "during a period of maximum CO2 potency, they have risen at a rate of 0.64degrees C per century, and currently show every indication of slowing down."

    Do try to keep your facts straight. O.14 deg C per decade on the low end; 0.4 deg C per decade may be the new norm. See Assessing global surface temperature.

    As for 'every indication of slowing down', look here, where the most recent 30 year trend is in excess of 0.5 deg C/decade: that isn't an indication of slowing down.

    Comments regarding temperature records alone -- off topic for this thread -- should go to one of those or one of the many similar threads.
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  31. In science you cannot "prove" anything, but you can disprove it. The onus is on the skeptics to disprove AGW.

    Despite having well over 100 year to do so, the "skeptics" have been unable to refute the theory of AGW/ACC, or offer a reasonable alternate theory that has withstood scrutiny.
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  32. Ron Crouch @ 27... Likewise, there are a great many well tested aircraft that have left the ground with many souls on board not to make it safely back to earth. The point being that everything has risk. Getting out of bed in the morning carries with it risk. But we take great pains to make sure that the things we do involve acceptably low levels of risk.

    This is the point of the article. At this point the risk models are high and yet we proceed each day as if there were no risk at all.

    There is one aspect of the risks that I don't think is addressed here. Slow and fast. Eating poisonous food or a crashing airplane is an immediate catastrophe. Climate is a very slow progressing catastrophe. If you are 60 years old today you will likely not see the worst of what is to come. If you are 20 today your situation is vastly different. As well, if you live in a poor nation you are more likely to be affected than if you live in a wealthy nation.

    The risks involved are very unevenly distributed.
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  33. Rob #32

    I agree with the point you are making Rob. I simply wanted to point out that food safety is far less than one might expect, making it a poor example (i.e. 4 of 186 restaurants in my city passed inspection with a full 25% being red carded). Sashimi anyone?
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  34. Due out in print Jan 2011 How Safe Is Our Food?. An advance Epub from the CDC.
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  35. Rob H #22

    "Small unexplained elements of a theory do not undermine a theory."

    The three 'inconsistencies' I listed are not 'small'. They go to the heart of AGW theory.

    What you are suggesting is the 'its there but we just can't measure it' argument which can hardly be called scientific rigour.
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    Moderator Response: [Daniel Bailey] Per Rob's comment at 22 above, in order to prove a theory wrong you need to have a competing theory that fully explains all current observations. And it needs to explain them better. You have merely pointed out three areas where the existing theory seeks more robust data, which no one denies. Conflating that into "since we can't know everything therefore we can know nothing" serves no useful purpose. Nor does it add anything to the dialogue, as has been pointed out to you repeatedly on other threads. Please come up with a viable physics-based alternative to AGW which explains what we have known about GHG's for over 150 years which also explains why anthropogenic CO2 doesn't act like the GHG that CO2 already in the carbon cycle does. That would be displaying scientific rigour. Anything less is sophistry.
  36. Ken Lambert said,

    Deep mixing of the ocean layers is inconsistent with suface layer acidification.


    Someone here is completely overlooking the concept of time-scales...
    0 0
  37. cloa513@1 You are completely wrong about food safety. A number of years ago I took part in a government funded project on the potential hazards associated with eating potatoes, a food mankind has been eating in quantity for a very long time. Potatoes produce glycoalkaloids in response to sunlight and/or physical damage, as a defence mechanism, and it is possible to poison yourself by eating potatoes. However the risks are small as most people know not to eat green or damaged tubers or tubers that have been stored for too long, and glycoalkaloids have a bitter taste so it is detectable. You may not be aware of research into the safety of foods, but that doesn't mean it doesn't exist.
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  38. Humans aren't actually that good with risk, and there are a range of reasons for the current situation that I could not do justice to.

    For example, we typically engage in what the risk managers and economists call 'future discounting' for issues whose consequences are not immediate. We also suffer from confirmation bias. For the case of the red berries, if they made us feel violently ill then sure, we would probably stop eating them. Then again, if the berries made us feel violently ill- but only the day after they made us feel euphoric, and they were addictive, then we may suddenly find our rational judgement of the risk is compromised. Again still, imagine if we could easily see carbon dioxide emissions; from cars, boilers, industrial plants, power stations and even in the color of the sunset. In that instance we may well have taken a different view of the risk. We delude ourselves all the time.

    That is exactly why we collect data and do science. The point of my article is that I think we need to adopt the correct risk framework whenever we communicate our science, and remind people that science can do this type of thing very well. You wouldn't get on an airplane otherwise.
    0 0
  39. Moderator (Daniel Bailey) #35

    "You have merely pointed out three areas where the existing theory seeks more robust data, which no one denies."

    Daniel, you should join the discussion in your own name - I, and no doubt others are not comfortable with players becoming umpires when the game is still going.

    Skeptics pointing out weaknesses and inconsistencies in AGW theory does not oblige them to offer a better fit theory to the observations.

    After all, it is the proponents of AGW who urge immediate drastic action to reduce CO2 release from fossil fuel burning and massive economic cost in converting to 'green' alternatives.

    The skeptics are not urging any such radical action. So it is for the proponents of such action to prove their case.

    What you are implying is that the standard of proof is to be decided by the fabled 'consensus' of independent researchers.

    I would agree that 'beyond reasonable doubt' is probably too tough a standard - because there is already 'reasonable doubt' in key areas such as I exampled in #15 and that it might take much more extensive data and research to achieve that standard if ever.

    'Balance of probabilities' is a much lesser hurdle and the AGW theorists would argue that they have already achieved that standard. Scientific theory is not proven by ballot however.

    The issue is whether or not there is a single (or two) contraverting pieces of robust observation which undermines the current AGW theory and points in a different direction. The answer will probably be found in measurement of OHC.
    0 0
    Moderator Response: [Daniel Bailey] It is the moderators job to keep threads on-topic. The topic of this thread is whether it is safe to double atmospheric concentrations of CO2. Your 3 items you flagged in your comment 15 above were on ocean acidification, OHC and SLR (all off-topic here). The burden is on you to find the appropriate threads for those and to posit a physics-based alternative to AGW specific to each of your concerns, as you have been repeatedly told in the past. If you wish to be taken seriously here, you will do so.
  40. The validity of scientific knowledge is ~always~ decided by consensus. Just like theory, consensus has a different meaning in a scientific context. Consensus is the accumulation of empirical observation and development of validated theory. Dismissal via "fabled 'consensus'" is no different than "just a theory". It is sophistry.

    Scientific theories are not disproven by pointing at loose threads, but rather by presenting new hypotheses that better explain the empirical observations.

    Using a "reasonable doubt" standard to determine the validity of scientific theories results in events like the Scopes Trial.

    There is no one single observation that will cause the scientific theory of anthropogenic global warming to collapse. This philosophy of "loose thread science" explains a great deal about the process of presenting multiple, contradictory & mutually exclusive contentions.

    Concerning OHC, that has been discussed elsewhere on this site. Further rehashing is not relevant here. Suffice it to say, depending on a currently unknowable quantity is no different than the "god of the gaps" rhetorical tactic common in evolution discussions.
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  41. Ken Lambert said,

    Skeptics pointing out weaknesses and inconsistencies in AGW theory does not oblige them to offer a better fit theory to the observations.


    But skeptics *do* have the obligation to *understand* the theory that they are criticizing. Your posts here clearly indicate that you don't, starting with your failure to understand something as basic as the time-scale difference between gaseous diffusion into surface water vs. that of deep ocean mixing.
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  42. 'Is it safe to double atmospheric CO2 over a 200 year period?'
    We don't know. Possibly not. Is it safe to live on this planet with 6.5 billion people, who all want to have their houses heated and their food and electricity supplied? Possibly not. But do we have a choice? Possibly not! Is it safe that many millions of people live in the Ganges delta without proper protection against floods? Not at all! Is it safe that many people live in aereas threatened by earth quakes without properly constructed houses? No!

    Small uncertainties in the rate of future warming are irrelevant to the risk assessment.
    What about big uncertainties? How big is the risk of future warming? Is there a real risk of more than 50 centimeters sea level rise? Why should a civilized society not be able to cope with such a sea level rise?

    Why have the skeptics never developed their own climate models and performed their own model experiments? They have. See Lindzen, Spencer, Soon, Baliunas, Akasofu!

    Why have the skeptics never compiled their own record of surface temperature? They have! See Loehle and others.

    It is easy to ask questions to climate skeptics and pretend, that they have no answer wihtout presenting their arguments. It is easy to point to risks whithout showing a way to avoid them.
    With the present state of technology there is no way to avoid doubling CO2 in the next century. We can better be prepared to cope with the effects of that doubling - if we are able to predict those effects!
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  43. "Why have the skeptics never developed their own climate models and performed their own model experiments? They have. See Lindzen, Spencer, Soon, Baliunas, Akasofu!"

    Cool. Where are their models? Can you show us the code to the GCM that, say, Soon and Baliunas wrote? Lindzen? Where's the source code to his GCM? Spencer? Same question.

    Oh, can't find the source ... OK, how about some model output from the GCMs these various people have written ... I'll settle for that.
    0 0
  44. fydijkstra @ 42... "'Is it safe to double atmospheric CO2 over a 200 year period?'
    We don't know. Possibly not..."

    Possibly not? A very, very small possibility. Virtually all the evidence coming out, and that has come out over the past 30 years, suggests that it is not safe. A very small amount of evidence suggests that it might not be a problem. Personally, in a situation like this, my inclination is to err on the side of caution.

    "With the present state of technology there is no way to avoid doubling CO2 in the next century."

    We certainly won't avoid it with the attitude that we can't avoid it. Technology is not the problem. The technology is there. It's ready. The only thing lacking is sufficient will.
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  45. @fydijkstra: " They have. See Lindzen, Spencer, Soon, Baliunas, Akasofu!"

    I guess the OP meant models that withstood scrutiny. These guys have all been shown wrong, many times.

    @KL: "The skeptics are not urging any such radical action."

    Actually, such radical action on fossil fuels is needed *whether or not* AGW theory is correct (it is, but some politically-minded commentators still want to debate it, I guess).

    Unless you've been living under a rock, fossil fuels are a strategic and ecological nightmare any way you cut it. The only people still pushing for oil are, well, oil people.

    I see that contrarians are still hard at work on Christmas. Gotta admire that dedication, even if it is completely misguided.

    Peace y'all, and merry Christmas if that's your thing.
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  46. Someone needs to speak out in favor of doubling the CO2 concentration. The plants are going to love it but nobody listens the them for fear of being dressed in a straitjacket.

    If I believed that doubling the CO2 concentration would cause a significant increase in global temperatures I would sell my electric car and buy a really large SUV.

    Here's wishing you all peace and prosperity in 2011 so that you can increase your carbon footprints.
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    Moderator Response: [muoncounter] Gratuitous cheap shots will get you nowhere.
  47. Ooops! Single malt scotch can affect one's grammar. What I meant was:

    "The plants are going to love it but nobody listens to them for fear of being dressed in a straitjacket."
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  48. @gallopingcamel: simply increasing CO2 won't make plants grow more.

    I don't think plants are too keen on increased temperatures and desertification. That's not what I heard from the grapevine. Yes, the actual grapevine.
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  49. "Small uncertainties in the conventional science are used to reinforce the notion that doubling atmospheric carbon dioxide is entirely safe."

    Not only that, but skeptics want us to think doing something about climate change will be unsafe.
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  50. To be fair to the skeptics, reducing our dependence on fossil fuels will be difficult. It won't be the end of civilisation as we know it, which is what skeptics think. But we do need to make the judgement, "Are the risks of global warming sufficient to justify the cost of abandoning fossil fuels?" I think it is worth it, but others may differ. It does bug me when they argue that global warming isn't happening, and our CO2 emissions aren't causing it.
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