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The Big Picture

Posted on 24 September 2010 by dana1981

Oftentimes we get bogged down discussing one of the many pieces of evidence behind man-made global warming, and in the process we can't see the forest for the trees. It's important to every so often take a step back and see how all of those trees comprise the forest as a whole. Skeptical Science provides an invaluable resource for examining each individual piece of climate evidence, so let's make use of these individual pieces to see how they form the big picture.

The Earth is Warming

We know the planet is warming from surface temperature stations and satellites measuring the temperature of the Earth's surface and lower atmosphere. We also have various tools which have measured the warming of the Earth's oceans. Satellites have measured an energy imbalance at the top of the Earth's atmosphere. Glaciers, sea ice, and ice sheets are all receding. Sea levels are rising. Spring is arriving sooner each year.  There's simply no doubt - the planet is warming (Figure 1).

warming world

Figure 1: Indicators of a warming world

Global Warming Continues

And yes, the warming is continuing. The 2000s were hotter than the 1990s, which were hotter than the 1980s, which were hotter than the 1970s. 2010 tied for the hottest year on record.  The 12-month running average global temperature broke the record three times in 2010, according to NASA Goddard Institute for Space Studies (GISS) data.  Sea levels are still rising, ice is still receding, spring is still coming earlier, there's still a planetary energy imbalance, etc. etc.

Contrary to what some would like us to believe, the planet has not magically stopped warming.  Those who argue otherwise are confusing short-term noise with long-term global warming (Figure 2).

escalator

Figure 2: The data (green) are the average of the NASA GISS, NOAA NCDC, and HadCRUT4 monthly global surface temperature anomaly datasets from January 1970 through November 2012, with linear trends for the short time periods Jan 1970 to Oct 1977, Apr 1977 to Dec 1986, Sep 1987 to Nov 1996, Jun 1997 to Dec 2002, and Nov 2002 to Nov 2012 (blue), and also showing the far more reliable linear trend for the full time period (red).

Foster and Rahmstorf (2011) showed that when we filter out the short-term effects of the sun, volcanoes, and El Niño cycles, the underlying man-made global warming trend becomes even more clear (Figure 3).

before/after filtering

Figure 3: Temperature data (with a 12-month running average) before and after the short-term factor removal

For as much as atmospheric temperatures are rising, the amount of energy being absorbed by the planet is even more striking when one looks into the deep oceans  and the change in the global heat content (Figure 4).

global heat content

Figure 4: Total global heat content. Data from Nuccitelli et al. (2012)

Over 90% of global warming goes into heating the oceans.  When taking the heating of the entire climate system into account, the planet has warmed at a rate equivalent to 4 Hiroshima atomic bomb detonations per second over the past 15 years.

Humans are Increasing Atmospheric Greenhouse Gases

The amount of greenhouse gases in the atmosphere - particularly carbon dioxide (CO2) - has been rising steadily over the past 150 years.  There are a number of lines of evidence which clearly demonstrate that this increase is due to human activities, primarily burning fossil fuels.

The most direct of evidence involves simple accounting. Humans are currently emitting approximately 30 billion tons of CO2 per year, and the amount in the atmosphere is increasing by about 15 billion tons per year.  Our emissions have to go somewhere - half goes into the atmosphere, while the other half is absorbed by the oceans (which is causing another major problem - ocean acidification). 

We also know the atmospheric increase is from burning fossil fuels because of the isotopic signature of the carbon in the atmosphere.  Carbon comes in three different isotopes, and plants have a preference for the lighter isotopes.  So if the fraction of lighter carbon isotopes in the atmosphere is increasing, we know the increase is due to burning plants and fossil fuels, and that is what scientists observe. 

The fact that humans are responsible for the increase in atmospheric CO2 is settled science.  The evidence is clear-cut.

Human Greenhouse Gases are Causing Global Warming

There is overwhelming evidence that humans are the dominant cause of the recent global warming, mainly due to our greenhouse gas emissions. Based on fundamental physics and math, we can quantify the amount of warming human activity is causing, and verify that we're responsible for essentially all of the global warming over the past 3 decades.  The aforementioned Foster and Rahmstorf (2011) found a 0.16°C per decade warming trend since 1979 after filtering out the short-term noise. 

In fact we expect human greenhouse gas emissions to cause more warming than we've thus far seen, due to the thermal inertia of the oceans (the time it takes to heat them).  Human aerosol emissions are also offsetting a significant amount of the warming by causing global dimming.  Huber and Knutti (2011) found that human greenhouse gas emissions have caused 66% more global warming  than has been observed since the 1950s, because the cooling effect of human aerosol emissions have offset about 44% of that warming.  They found that overall, human effects are responsible for approximately 100% of the observed global warming over the past 60 years (Figure 5).

knutti breakdown

Figure 5: Contributions of individual forcing agents to the total change in the decadal average temperature for three time periods. Error bars denote the 5–95% uncertainty range. The grey shading shows the estimated 5–95% range for internal variability based on the CMIP3 climate models. Observations are shown as dashed lines.

There are also numerous 'fingerprints' which we would expect to see from an increased greenhouse effect (i.e. more warming at night, at higher latitudes, upper atmosphere cooling) that we have indeed observed (Figure 6).

prints

Figure 6: Observed 'fingperprints' of man-made global warming

Climate models have projected the ensuing global warming to a high level of accuracy, verifying that we have a good understanding of the fundamental physics behind climate change.

Sometimes people ask "what would it take to falsify the man-made global warming theory?". Well, basically it would require that our fundamental understanding of physics be wrong, because that's what the theory is based on.  This fundamental physics has been scrutinized through scientific experiments for decades to centuries.

The Warming will Continue

We also know that if we continue to emit large amounts of greenhouse gases, the planet will continue to warm. We know that the climate sensitivity to a doubling of atmospheric CO2 from the pre-industrial level of 280 parts per million by volume (ppmv) to 560 ppmv (we're currently at 390 ppmv) will cause 2–4.5°C of warming. And we're headed for 560 ppmv in the mid-to-late 21st century if we continue business-as-usual emissions.

The precise sensitivity of the climate to increasing CO2 is still fairly uncertain: 2–4.5°C is a fairly wide range of likely values.  However, even if we're lucky and the climate sensitivity is just 2°C for doubled atmospheric CO2, if we continue on our current emissions path, we will commit ourselves to that amount of warming (2°C above pre-industrial levels) within the next 75 years.

The Net Result will be Bad

There will be some positive results of this continued warming. For example, an open Northwest Passage, enhanced growth for some plants and improved agriculture at high latitudes (though this will require use of more fertilizers), etc. However, the negatives will almost certainly outweigh the positives, by a long shot. We're talking decreased biodiversity, water shortages, increasing heat waves (both in frequency and intensity), decreased crop yields due to these impacts, damage to infrastructure, displacement of millions of people, etc.

Arguments to the contrary are superficial

One thing I've found in reading skeptic criticisms of climate science is that they're consistently superficial. For example, the criticisms of James Hansen's 1988 global warming projections never go beyond "he was wrong," when in reality it's important to evaluate what caused the discrepancy between his projections and actual climate changes, and what we can learn from this. And those who argue that "it's the Sun" fail to comprehend that we understand the major mechanisms by which the Sun influences the global climate, and that they cannot explain the current global warming trend. And those who argue "it's just a natural cycle" can never seem to identify exactly which natural cycle can explain the current warming, nor can they explain how our understanding of the fundamental climate physics is wrong.

There are legitimate unresolved questions

Much ado is made out of the expression "the science is settled."  The science is settled in terms of knowing that the planet is warming rapidly, and that humans are the dominant cause.

There are certainly unresolved issues.  As noted above, there's a big difference between a 2°C and a 4.5°C warming for a doubling of atmospheric CO2, and it's an important question to resolve, because we need to know how fast the planet will warm in order to know how fast we need to reduce our greenhouse gas emissions. There are significant uncertainties in some feedbacks which play into this question. For example, will clouds act as a net positive feedback (by trapping more heat, causing more warming) or negative feedback (by reflecting more sunlight, causing a cooling effect) as the planet continues to warm?  And exactly how much global warming is being offset by human aerosol emissions?

These are the sorts of questions we should be debating, and the issues that many climate scientists are investigating. Unfortunately there is a very vocal contingent of people determined to continue arguing the resolved questions for which the science has already been settled. And when climate scientists are forced to respond to the constant propagation of misinformation on these settled issues, it just detracts from our investigation of the legitimate, unresolved, important questions.

Smart Risk Management Means Taking Action

People are usually very conservative when it comes to risk management.  Some of us buy fire insurance for our homes when the risk of a house fire is less than 1%, for example.  When it comes to important objects like cars and homes, we would rather be safe than sorry.

But there is arguably no more important object than the global climate.  We rely on the climate for our basic requirements, like having enough accessible food and water.  Prudent risk management in this case is clear.  The scientific evidence discussed above shows indisputably that there is a risk that we are headed towards very harmful climate change.  There are uncertainties as to how harmful the consequences will be, but uncertainty is not a valid reason for inaction.  There's very high uncertainty whether I'll ever be in a car accident, but it would be foolish of me not to prepare for that possibility by purchasing auto insurance.  Moreover, uncertainty cuts both ways, and it's just as likely that the consequences will be worse than we expect as it is that the consequences won't be very bad.

We Can Solve the Problem

The good news is that we have the tools we need to mitigate the risk posed by climate change.  A number of plans have been put forth to achieve the necessary greenhouse gas emissions cuts (i.e. here and here and here).  We already have all the technology we need.

Opponents often argue that mitigating global warming will hurt the economy, but the opposite is true.  Those who argue that reducing emissions will be too expensive ignore the costs of climate change - economic studies have consistently shown that mitigation is several times less costly than trying to adapt to climate change (Figure 7). 

Figure 7:  Approximate costs of climate action (green) and inaction (red) in 2100 and 2200. Sources: German Institute for Economic Research and Watkiss et al. 2005

This is why there is a consensus among economists with expertise in climate that we should put a price on carbon emissions (Figure 8).

should US reduce emissions

 

Figure 8: New York University survey results of economists with climate expertise when asked under what circumstances the USA should reduce its emissions

The Big Picture

The big picture is that we know the planet is warming, humans are causing it, there is a substantial risk to continuing on our current path, but we don't know exactly how large the risk is. However, uncertainty regarding the magnitude of the risk is not an excuse to ignore it. We also know that if we continue on a business-as-usual path, the risk of catastrophic consequences is very high.  In fact, the larger the uncertainty, the greater the potential for the exceptionally high risk scenario to become reality. We need to continue to decrease the uncertainty, but it's also critical to acknowledge what we know and what questions have been resolved, and that taking no action is not an option.  Th good news is that we know how to solve the problem, and that doing so will minimize the impact not only on the climate, but also on the economy.

The bottom line is that from every perspective - scientific, risk management, economic, etc. - there is no reason not to immeditately take serious action to mitigate climate change, and failing to do so would be exceptionally foolish.

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Comments 1 to 50 out of 200:

  1. Overall, I think this is an excellent article. But there is still room for improvements in a few spots. The split infinitive, for example, has to go.

    Now don't get me wrong: I am not one of those sticklers who believes that every split infinitive is wrong. But THIS one really grates on my ears! I am referring to:

    "It's important to every so often take a step back and see how all of those trees comprise the forest as a whole."

    While we are fixing the split infinitive, another slight change of wording also makes a marked improvement. I suggest:

    "It's important to take a step back every now and then to see how all of those trees form the forest as a whole."

    A more substantial point: I -wish- it were as easy as simply asserting, that falsification "would require that our fundamental understanding of physics be wrong, because that's what the theory is based on."

    If it were that simple, I doubt that Freeman Dyson would still be objecting to the evidence. And indeed, there is a lot of data collection and interpretation added on top of that "fundamental understanding of physics" to reach the conclusion.

    As long as such a prominent physicist as Dyson objects, we cannot expect to get very far by claiming "the theory is based on our fundamental understanding of physics".

    Now don't get me wrong, I do not agree with Dyson, and am I mystified and disappointed that he objects. But I do share at least a little of his skepticism concerning the models. It really IS hard to know if the model is correct. Especially when the rebuttal on this very website does not even address the objections Dyson raised: it says nothing about whether or not the new models still rely on 'fudge factors', whether or not they now take into account dust and clouds, etc.

    IOW: both this article and that could use some strengthening in similar ways. But this one is already very good, and needs little more to reach perfection -- especially if the other is strengthened as well.
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  2. BTW: I suppose I should add: if the models still rely on "fudge factors", then the claim that the conclusion is based on "our fundamental understanding of physics" simply does not hold water.
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  3. Nice work Dana! This puts everything nicely into perspective.

    I've wondered about creating a list of different aspects of climate change and putting them into categories in a simple graphic like: 1) Basic physics 2) Settled science 3) Observations 4) New research 5) Uncertainties (or something like that).

    I think the average person tends to think of science as being black and white. It either is or it isn't. Good guys and bad guys. Us and them. Etc. And I know science is just not about absolutes. If there were a way to help people understand this basic aspect of climate it might go a long way toward opening some eyes and changing some minds.
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  4. Nice post!

    Oftentimes we get bogged down discussing one of the many pieces of evidence behind man-made global warming, and in the process we can't see the forest for the trees.

    Using another optical analogy, no depth of field.
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  5. MattJ - the question about model should refer to Models arent reliable argument.

    But yes, models most certainly do take into account clouds and aerosols. The closest thing to "fudge factors" would be parameterizations - empirical equations that relate some variable response to inputs. (eg evaporation as response to sea-temp, wind etc). However, it is important to note that the "tuning" of empirical determinations match a specific variable to factors affecting it, NOT to fiddling knobs so that you match observed climate to model. Have a look at this FAQ for example. Further questions to appropriate argument (or ask the modellers themselves).
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  6. If I may pose a heretical question - and no offense meant - valuable as these introductory-level posts may be, wouldn't it be better for our expert authors to break some new ground, e.g. by undertaking new research or having new insights, rather than reinventing the wheel (that is, by restating well-known facts in simple terms)?
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  7. Blah, blah, blah. The claim that man is responsible for virtually all warming is pure speculation. To say that is to assume that temperatures would have basically stayed the same over this whole period. Temperatures have not stayed static for any thirty year period ever.
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  8. C'mon Hunt. Do you really expect the average reader of the sports pages to dive into the fiercely technical waters at Real Climate or Science of Doom?

    The whole objective of John's project of
    1) identify a single argument then
    2) describe the scientific background at 3 levels from simple through to full-bore science essay is designed to allow people who get stuck in an argument with a doubter of the science to back up their points with accurate material - pitched at the right level.

    It's not the writers who are reinventing the wheel, it's the conversational, opinionated know-nothings who revive and recycle the same old talking points.
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  9. Very good post.

    Small addition:

    Where you write
    "In fact we expect human greenhouse gas emissions to cause more warming than we've thus far seen, due to the thermal inertia of the oceans (the time it takes to heat them)."

    Aerosol cooling is another important factor that we haven't yet seen the full amount of warming that one would expect from GHG emissions. See eg Ramanathan and Feng (2009) http://www-ramanathan.ucsd.edu/publications/Ram-&-Feng-ae43-37_2009.pdf or Raes and Seinfeld short piece in AE last year.
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  10. cruzn246, no temperatures have not stayed completely static in any 30 year (or 30 minute) period ever. However, they have also never shot up a degree C in a hundred year period without a specific cause. In this case, the cause is us.
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  11. Nice article. One criticism:

    Quote: "Sometimes people ask 'what would it take to falsify the man-made global warming theory?'. Well, basically it would require that our fundamental understanding of physics be wrong, because that's what the theory is based on."

    I think people asking that question - 'what would it take to falsify the man-made global warming theory?' - are making an ostensibly reasonable request, since falsification is one way of demarcating scientific from non-scientific theories. But usually it's used by denialists to muddy the waters and claim that climate science is not falsifiable and thus not 'proper science', because it proposes no theories or statements that are falsifiable. Here's a UK libertarian example.

    Here's my philosophy of science 101 take on this - would love to hear better informed views. "All swans are white" is a falsifiable theory; if you find a black swan, theory falsified. In the same way, Einstein's theory of relativity is falsifiable - Eddington took photos of an eclipsed sun to measure the predicted impact of gravity on light from a distant star. The theory wasn't falsified - but in principle, it is. That's a criterion for good science - unlike, say, "George Bush is a 12 foot shapeshifting lizard from another dimension". "But he looks human." "Exactly."

    AGW theory appears unfalsifiable because - it would seem - we need some future date to arrive before the theory can be falsified. It's quite a nice trick: it does appear at first glance that we have to wait for some point in the future to falsify climate theory - and, of course, if the climate does warm, that only confirms the theory, it doesn't falsify it.

    They're wrong, though. Surprise surprise. Two ways they're wrong: first, if AGW won't be falsifiable until some point in the future, that ALSO means anti-AGW hypotheses are equally unfalsifiable - if they require us to wait for the future to find out. (Actually, of course, AGW theory does make future, falsifiable predictions, but let's put that aside for the moment.)

    So the next question is, do we need to wait for the future before we can have any faith in climate science? No - there are supporting pillars that are falsifiable. You can come up with plenty of null hypotheses: for example, the earth isn't warming. To turn that round, "The earth is warming" is entirely falsifiable, in principle. Same as the theory of relativity, it just hasn't been falsified - and likely won't be. Clearly, the null hypothesis - say, "the earth hasn't warmed since the 1950s" has been. How about "humans don't cause global warming?" Well, it would need breaking down a bit, but that's easy enough: "co2 doesn't cause atmospheric warming" and "humans aren't putting co2 into the atmosphere" are trivial to falsify.

    So again, it's just one of those lovely, sciencey-sounding things that 'skeptics' like, but that actually supports their argument not at all.
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  12. Just to add: good theories carry on standing up against attempts to falsify - here's a story I just read where Einstein's work once again survives. As they say, "our results agree with Einstein's theory – we weren't expecting any discrepancies and we didn't find any."
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  13. Gah! Sorry, should have added this before: what's most perverse and enraging about the denialosphere is that no falsifiable theories are ever proposed - or when they are, and they're falsified, they just duck and dodge. And then some have the temerity to accuse climate scientists of being unscientific? Graaah.
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  14. Dan Olner #11

    Many things could falsify the "AGW theory". Less downward longwave radiation in the last few decades, for example. Or more OLR with some corresponding other forcing that would justify it in quantity.

    That would mean all those extra GHG in the atmosphere are not having an effect. Which would mean well-established theories like Beer-Lambert Law and Planck Law would be wrong (they are actually so well established that they deserve the status of "laws"of physics).

    That's why dana said that "our fundamental understanding of physics [would be] be wrong".
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  15. Hey John, Dan Olner's assertion that greenhouse gas induced warming is not a falsifiable theory and therefore not science is a 'skeptic' argument for which you don't have a refutation! I've seen it used a few times here and there, so perhaps it needs one.

    Engage your brain Dan. I'm sure you can think of a few ways to falsify AGW theory if you try. For example if any of the phenomenon in John's Ten fingerprints of global warming post were not observed to be occurring, then that would constitute evidence that something was amiss with the theory.
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  16. Sorry Dan, I mouthed off without reading your post properly, and instead made that assumption based on Alexandre's response. I see that you are not in fact making the assertion that AGW theory is not falsifiable.
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  17. Thanks, Adelady, for your good comment (#8).

    My doubts about the wisdom of this project will of course vanish immediately if someone can assure me that one or more of these basic posts has had some positive effect on a denier.
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  18. huntjanin:

    Dont' just think about turning deniers. Also think about preventing soft "believers" (yuck) from turning.
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  19. huntjanin: "My doubts about the wisdom of this project will of course vanish immediately if someone can assure me that one or more of these basic posts has had some positive effect on a denier."

    Related to that, just been watching the late Steve Schneider tackle a room of sceptics. It's a fantastic insight into a range of sceptic mindsets that you just can't get from the interwebs. A number of them clearly have the wherewithall - given the right information and time - to piece together the story. They've just been exposed to some misleading information. But one or two - the doctor near the start - ask Schneider for an explanation on something, get a really clear explanation, and then repeatedly shout him down saying he hasn't answered the question.

    The heartening thing seems to be, he's the rarity, not the norm. The question then is, what's the ratio of rational to irrational on the web? And are people that come here a self-selecting audience?

    Oh - here's a link to the video.

    Clearly, it wasn't hard to gather a doubting audience in one place, willing to listen to a prominent scientist. I suspect blog science suffers far more from ghettoisation.

    Maybe the answer is that skepticalscience.com and other sites are needed, but until the information here gets out into meatworld public forums, its impact may be lessened.
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  20. Dr. Schneider does a great job addressing the falsifiability of climate science in a lecture he gave back in February which has been given the title, "Climate Change: Is the Science 'Settled'?"

    In summary he states...
    "Climate system science, like others, is really a preponderance of evidence based outcome. It is not falsifiable. Not in the short run....We do not falsify by single experiments. We falsify on the basis of accumulated numbers of papers and number of bits of information."
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  21. First i want to say this is an excellent post.

    @huntjanin... When i am arguing with someone about AGW I am not focused on convincing them as they are usually too invested in their denial. What I try to keep in mind is the possible audience that is listening to or reading the comments. Those are the ones I am trying to inform by offering civil, reasoned, and fact based replies.

    I have used this site as a resource for some time now. The primary reason is to better educate myself which with this 50+ year old brain is a struggle at times. High school and college science was a very long time ago. Thanks to John and all the contributors who devote so much time and energy to keeping this a much needed model of civil discourse and learning.
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  22. @Dan Older, #11,

    Excursions in to the philosophy are usually considered OT, but here is my 2c.

    "Falsifiability" is a good criterion to demarcate science from non-science. In that respect, it resembles Occam's Razor or Hume's Fork. However, it is not a good criterion to assess a branch of science, as climate science has become.

    Scientific theories are usually composite and stated as generally as possible. A black swan may falsify the simple hypothesis "All swans or white" but not the more general hypothesis "Most swans are white" or even "Some swans are white". With inductive logic, it is often easier to modify the hypothesis than reject it.

    The difficulty of "falsifying" a science is best illustrated by a story from physics. At the start of the 19th century, astronomers found that the planet Uranus was not appearing as predicted by Newton's Laws. Did they therefore stop using Newton's Laws? Of course not - the laws were too accurate in other places to drop them completely. Instead, two astronomers (Adams and Leverrrier) used the discrepancies to propose that there was another planet beyond Uranus. There prediction was verified when the planet Neptune was observed in 1846, exactly where it was predicted to be.

    Fine, a triumph of science. Bur later in the century discrepancies were found in the orbit of Mercury, and again the existence of another planet was proposed (called Vulcan). But Vulcan was never observed, and the discrepancy was later correctly explained by Einstein's Theory of Relativity. However, in the interim, Newton's Laws had continued to be used with gusto.

    So "falsifiability" is too simple a criterion to judge a large and expansive scientific programme. It may work when a science is in its infancy - the best example I can think of is Fred Hoyle's Steady State Theory of the cosmos, which was slain by the simple observation of the microwave remnants of the Big Bang. But the Big Bang theory iteslf is now so complex and composite it is doubtful if a single observation could dethrone it overnight.

    The reference you gave was somewhat confused - it referred to a science discussion in 1961 as if it had contemporary relevance, and provided no instances where climate scientists were making predictions that were not falsifiable. I find deniers take simple lacunae in the theory of AGW and immediately jump up and down saying "Falsified! Falsified!".

    PS Just read Michael Searcy's comment #20... Dr Schneider states it much more succinctly than me!
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  23. If there is a single ongoing experiment offering the best hope of crisply falsifying the notion of anthropogenic climate change, perhaps it's night time surface atmospheric temperatures? This is sampled with ancient, thoroughly understood instrumentation, comprehensively deployed, no confounding factors if the simplest and most transparent data conditioning is permitted.

    A reasonable person might conclude that if night time temperatures were refusing to behave "properly," we may have a wee problem with the notion of AGW. As it stands, overnight temperatures are behaving exactly as we'd expect; the behavioral details of the decline of diurnal surface temperature variation seem impossible to explain by other means.

    Perhaps it's the very simplicity of this message of surface temperature records which compels "skeptics" to discard surface temperature records as false. Failing a scientific explanation, speculations about fraud or incompetence are all that's left to discount the first, easiest, most bulky and unequivocal evidence of AGW.

    Ironically, past such simple matters as diurnal temperatures, "skeptics" seem to be becoming lost in the myriad of complicated knock-on findings of researchers delving into climate change. The more evidence they demand, the less perfectly atomic and hermetic new evidence will be; ignoring the obvious means dealing with the arcane.

    Huntjanin, for my part I don't think any but the very softest and least committed "skeptic" will be swayed by -any- argument based on science. This "debate" is not really about science at all. For helping ordinary people who are curious about this matter and want to know what all the fuss is about, offering simplified explanations with pointers to details seems a worthwhile exercise.

    Constructing these basic explanations is a fascinating exercise in itself, a matter of teasing essential concepts out of things often very complicated.
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  24. Adelady #8

    "It's not the writers who are reinventing the wheel, it's the conversational, opinionated know-nothings who revive and recycle the same old talking points."

    What is it with something about 'she who is without sin casting the first stone?'

    Presumably in your view only deniers and sceptics (why not call them tanks?) have the same old talking points.

    As if the age of a point has anything to do with its value.

    Old talking points arise because they might be uncertain, difficult, controversial and not resolved - like the real contribution of CO2GHG to warming, WV and CO2 interaction, OHC measurement, etc etc.

    BTW who is dana1981 anyway - he/she seems to be recycling lots of 'old talking points' lately.
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  25. Nice post. I have to add that I think the conclusion can be tightened up a bit.

    We may not know the exact risk but we have a pretty good idea what the ballpark figures are in terms of risk management. It's not difficult when we can clearly see that continued AGG emissions will more than likely result in extreme GW, which will most likely result in a severe mass extinction event.

    It clearly will most likely result in to collapse of modern civilization and very probably the reduction of the human species to very low numbers. There is also a possibility of the run away GH effect which would annihilate life.

    So the statement "uncertainty regarding the magnitude of the risk" in the conclusion is a bit miss leading.
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  26. Re: Ken Lambert (24)
    "What is it with something about 'she who is without sin casting the first stone?'"
    Actually, it's "If any one of you is without sin, let him be the first to throw a stone at her." Remember, the society of the day was patriarchal, so the gender of the expression is male. (but perhaps you were adapting it to adelady?)
    "Presumably in your view only deniers and sceptics (why not call them tanks?) have the same old talking points."
    Those same old talking points you reference are the ones whose science the "deniers and sceptics" fail time and again to overcome.
    "As if the age of a point has anything to do with its value."
    Well-spoken, sir.

    The Yooper
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  27. A good paper on why a large portions of the general public, journalists, and policy makers dont get the "...scale of the problem and the urgency of required action"
    is :

    What psychology can teach us about our response to climate change
    http://www.guardian.co.uk/environment/blog/2010/sep/23/climate-change-psychology-response-scepticism

    "Simply presenting the facts and figures about global warming has failed to convince large portions of the general public, journalists, and policy makers about the scale of the problem and the urgency of required action. From a psychologist's perspective this disconnect is not surprising."
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  28. Following from PaulM's comment, this is a useful article:

    The Psychology of Global Warming (AMS, full text pdf)

    Leaving aside that little group tagged by Leiserowitz as the "dismissive," if we take heed of what we've learned of how people think, our communications actually can be made more effective, more robust in the face of industrial PR.
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  29. cruzn246 #7 - I suggest you actually click the links and learn something. There's a pretty darn big difference between scientific evidence and "pure speculation."

    bverheggen #9 - valid point, I may add a bit on aerosols. I wrote a rebuttal on the subject recently which I didn't link in this article.

    Dan Olner #11 - there's a difference between what it would take for AGW to be wrong (our understanding of physics would have to be wrong) and what it would take to disprove AGW. To disprove the theory, just demonstrate that the planet is not warming or climate is not changing as it predicts. I recommend you click the 'fingerprints' link in the article to see what I mean.

    Ken Lambert #24 - perhaps you're unfamiliar with Skeptical Science. The purpose of the site is to debunk false skeptic arguments with scientific evidence.

    paulm #25 - I'll consider rewording the conclusion a bit.
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  30. Dana, I think this is a great post. I'm forwarding it to my relatively climate naive sister so she has a good entry point to the amazing resources on this web site.

    One thing regarding falsification. (This particular line of argument from deniers drives me completely batty!) I would argue that it's more correct to say that ober 50 years AGW has been repeatedly subject to intense attempts at falsification by skeptical scientist and it has passed those tests repeatedly, so that now it would take a truly astonishing series of events/findings to shake the hard won belief in it that most now scientists have.

    The way it's put now is strictly true, but it sounds a little condescending for those not very aware of those physical principles you speak of (I presume this level of explanation is targeted at such people). It reads a bit like "us smart people thought this up using theories that you can't possibly understand, so don't question it." That plays perfectly into the whole anti-elitism meme that lurks beneathe this debate. It also somewhat undersells the great body of observational data that does not rely on those physical principles.

    Perhaps some way for people to understand how they depend on those physical principles in their every day lives would help bring it home too.
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  31. (I don't claim to be a specialist in this area but I do have a science degree )

    When talking with friends and colleagues who don't have a science background I tend to use the following way of describing what a few degrees centigrade rise really means ...

    "The numbers one ,two , three and four don't sound much. Two centimeters seems a small number . However to understand a two degrees (c) rise in temperature think what you would say if I suggested you lift (by yourself) Mount Everest by two centimeters - it's only a small number so it should be easy . Now think about how much disruption must have occured to make a one degree centigrate rise to the temperature of the Earth .... and then project what the consequences could be of a two or three degree rise - a small number can mask gigantic changes.... This is the impact of fossil fuels on the green house effect "
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  32. Retification...
    Do you ever wonder, "Is the thermostat of nature" is not stuck?
    If it is stalled antropogenic actions has great potential to be the cause of all this damage.
    I do not believe that acts falcification of data.
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  33. Tarcisio, please rephrase your comment. I don't understand your point.
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  34. Tom #33
    I go wrait with may poor english escuseme...
    If the thermostat of the climate is brook or is out of range, the global warm has great potential of be antropogenic. And in this case the science is rigth.
    Only the target of resershing is bad. It's look to the fingeprint only.
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  35. Re: Tarcisio José D'Avila (32,34) and Tom Dayton (33)

    If I understand Tarcisio José D'Avila correctly, he is postulating the existence of a broken "climate thermostat". Broken, because it is not correcting for the actions of man's fossil fuel CO2 emissions. An iteration of the Gaia hypothesis, I believe.

    He believes the science of anthropogenic warming is right, but that it only is warming because the thermostat itself is broken. Or something like that.

    If I've misunderstood, I apologize.

    The Yooper
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  36. Tariscio - I would love to read your comments, but find your translations difficult to follow.

    I would suggest including both your native language (Spanish?) in appropriate detail, and using Google translate to produce an additional English version. Many of us can read or at least puzzle out other languages.
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  37. Well Dunkerson, you think it is all us? I mean think about it. How can they claim that a change in temperature is completely or even mostly the responsibility of man when we are not even at the point when we truly know what makes our temperatures change and how much they change anyway. We have never been around at this point in a glacial period, so who are we to know what happens when it gets to this point?
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  38. MattJ #1
    "I do not agree with Dyson, and am I mystified and disappointed that he objects."

    As per your comment, his interview on YouTube may help. To see, just google his name, etc. I dont think he is saying global warming is not real as much that stratospheric cooling might be a bigger problem.

    Similarly, while he plays down the imperative to reduce fossil fuels (towards the end of the video), in his book, Disturbing the Universe, he pretty much writes that humanity missed its opportunity in the sixties to go nuclear due to unwarranted alarmism, such that he was more optimistic about the ability to build safer reactors.
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  39. Anyone seen this?

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  40. Cruzn @ 39 - is that by that German school teacher?.
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  41. Yes, three years ago Beck picked a fight with a dead man... and lost. Apparently this nonsense is coming back up again because Beck died this week.

    In brief, decades ago Guy Stewart Callendar took atmospheric CO2 readings by various people all over the world (see the list of name at the bottom of Beck's chart) and analyzed them in an effort to determine if there was any trend in CO2 levels. He found that alot of the readings showed a steadily increasing trend line, but there were also alot of outliers... all on the high side and all downwind of major industrial centers. He therefor reasoned that these high readings were being caused by recent emissions that had not yet mixed through the atmosphere and excluded them.

    Beck, forty years after Callendar's death, called this 'scientific fraud' and insisted that the only proper way to do a scientific study is to include ALL of the data... even that which is clearly erroneous. His results, based on including readings from right outside coal plants (which were, of course, one of the places such readings were taken) yielded the graph above... further skewed by the fact that there were very few readings available for the early part of the chart and almost all of them were from industrial regions.

    Of course Beck's paper was provably nonsense the day it came out. Multiple stations around the world have long since validated Callendar's results and satellite analysis has also confirmed it in recent years.

    There is no greater proof of the deficiency of the 'skeptic' position than their insistence on holding fast to pure fiction.
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  42. PS: I should have also mentioned ice core CO2 records... direct readings of CO2 levels in air bubbles. Which ALSO verified Callendar's results and made Beck's analysis obviously false before he even published it.
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  43. #41: "there were also alot of outliers... all on the high side and all downwind of major industrial centers."

    Isn't that direct experimental proof that increased atmospheric CO2 is anthropogenic?
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  44. muoncounter, that's an interesting point. We hear so much about how human CO2 emissions are tiny compared to natural emissions, but when looked at geographically there is a very clear human signal in the CO2 satellite maps (and the earlier data). Presumably this is because natural emissions are spread out around the globe and balanced by natural sinks in nearly equal measure. However, human emissions are comparatively very concentrated... and the areas with the greatest emissions (cities) also have the most minimal carbon sinks (because there are few plants).

    Still, this does NOT (by itself) prove global atmospheric CO2 increases are due to humans. If global carbon sinks were able to absorb the extra amount we'd see locally elevated CO2 from humans, but the long term trend would be flat. Since we see locally elevated amounts AND a positive trend it is clear that carbon sinks are not able to handle all of the additional CO2.
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  45. 44: "Since we see locally elevated amounts AND a positive trend it is clear that carbon sinks are not able to handle all of the additional CO2. "

    Agreed. But if elevated amounts of atmospheric CO2 are in close context with power plants, urban areas, etc, on the local level, it would be completely illogical to insist that the global total fossil fuel emissions does not result in increased global atmospheric CO2.
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  46. So how do you all explain the big drops in the CO2 chart from Beck? Did folks quit burning coal in those years? did winds mysteriously change directions for years?

    BTW, Ice cores are not that accurate. The most recent do not show the so called increase we are seeing.

    Can someone tell me how warm it would be if no CO2 was in the atmosphere?
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  47. "...if no CO2 was in the atmosphere?"

    Is anybody going to rise to that bait? Take the refusal to acknowledge CBDunkerson's remarks concerning Beck as a hint as to whether the little sardine is worth biting.
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  48. @cruzn246, first, please answer this simple question: are you here to learn, or simply repeat denier arguments you've read elsewhere? Because if it's the latter, then kindly abstain from it. Instead, look up those arguments in the list compiled on this site to get an accurate rebuttal. Thanks.

    "So how do you all explain the big drops in the CO2 chart from Beck?"

    Beck's chart is inaccurate, so who knows what the drops and bump means. For example, if Beck's primary sources were in Germany, then it would make sense for the big bump during WWII, as the country's industry went into overdrive.

    In any case, the graph (and the paper it came from) was thoroughly debunked.

    "BTW, Ice cores are not that accurate. The most recent do not show the so called increase we are seeing."

    Perhaps not (I'd have to check), but the older one disprove Beck's graph.

    "Can someone tell me how warm it would be if no CO2 was in the atmosphere?"

    Off-hand, I remember it being something akin to 30C, but I could be wrong. What's that got to do with it?
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  49. ...sorry, I meant "30C colder".
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  50. The whole thing about CO2 just leaves me baffled. Of course it is explained that CO2 lags for whatever reason when a warmup occurs. OK, so after that it becomes a driver. So why the heck can you never go anywhere in the temperature history and find one stinking time that temperature peaked after CO2 peaked? I mean if it's driving then.........Face it people, the big greenhouse gas here is water vapor.

    I am not saying it is a zero factor, but till we really see some temperatures out of the norm, which we are not close to seeing, I can't buy this notion about CO2 causing some big change here. We are well within norms. We are still in what has been a relatively warm period called the Holocene, and the simple fact is that we will probably see higher temps then this before this whole climate system flips. It happened before and it will happen again. And CO2 has little or nothing to do with it. it is a minor player in the whole climate system. Greenouse gases allow us to trap heat, but they are not the big players in climate change. The whole system is so complex we barley know how it works but the balance of solar factors, albedo, and ocean temperatures and currents are all bigger players. Anyone who knows anything about our glacial climatology should know that we are bound to stay warm until we see a radical change in ocean currents. That is probably the big tripper in the system. When that gulf stream doesn't flow to Europe anymore, usually about the time FL is mostly water covered, things flip.
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