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A Comprehensive Review of the Causes of Global Warming

Posted on 20 January 2012 by dana1981

At Skeptical Science, we have examined several recent studies which have used a number of diverse approaches to tease out the contributions of various natural and human effects to global warming.  Here we will review the results of these various studies, and a few others which we have not previously examined, to see what the scientific literature and data have to say about exactly what is causing global warming.

All of these studies, using a wide range of independent methods, provide multiple lines of evidence that humans are the dominant cause of global warming over the past century, and especially over the past 50 to 65 years (Figure 1).

HvA 50 years

Figure 1: Net human and natural percent contributions to the observed global surface warming over the past 50-65 years according to Tett et al. 2000 (T00, dark blue), Meehl et al. 2004 (M04, red), Stone et al. 2007 (S07, green), Lean and Rind 2008 (LR08, purple), Huber and Knutti 2011 (HK11, light blue), and Gillett et al. 2012 (G12, orange).  This has been added to the SkS Climate Graphics Page.

Note that the numbers provided in this summary post are best estimates from each paper.  For the sake of simplicity we have not included error bars, but we have provided links to the original research for those who would like to see the uncertainty ranges in each estimate.

A Quick Look at the Various Effects on Global Temperature

Most of the studies discussed below looked at the same few influences on global temperature, because they are the dominant effects.

As we know, human greenhouse gas (GHG) emissions warm the planet by increasing the abundance of greenhouse gases in the atmosphere, thus increasing the greenhouse effect.

Solar activity also warms or cools the planet by increasing or decreasing the amount of radiation reaching the Earth's atmosphere and surface.

Volcanic activity generally cools the planet over short timeframes by releasing sulfate aerosols into the atmosphere, which block sunlight and reduce the amout of solar radiation reaching the surface.  However, unlike many greenhouse gases, aerosols are washed out of the atmosphere quickly, mostly after just 1-2 years.  Thus the main volcanic impact on long-term temperature changes occur when there is an extended period of particularly high or low volcanic activity.

Human aerosol emissions (primarily sulfur dioxide [SO2]) also tend to cool the planet.  The main difference is that unlike volcanoes, humans are constantly pumping large quantities of aerosols in the atmosphere by burning fossil fuels and biomatter.  This allows human aerosol emissions to have a long-term impact on temperatures, as long as we keep burning these fuels.  However, because aerosols have a number of different effects (including directly by blocking sunlight, and indirectly by seeding clouds, which both block sunlight and increase the greenhouse effect), the magnitude of their cooling effect is one of the biggest remaining uncertainties in climate science.

The El Niño Southern Oscillation (ENSO) is an oceanic cycle which alternates between El Niño and La Niña phases.  El Niño tends to shift heat from the oceans to the air, causing surface warming (but ocean cooling), whereas La Niña acts in the opposite manner.  As we'll see, a few studies have begun examining whether ENSO has had a long-term impact on global surface temperatures.  Because it's a cycle/oscillation, it tends to have little impact on long-term temperature changes, with the effects of La Niña cancelling out those of El Niño.

There are other effects, but GHGs and SO2 are the two largest human influences, and solar and volcanic activity and ENSO are the dominant natural influences on global temperature.  Now let's see what the scientific literature has to say about the relative influences of each effect.

Tett et al. (2000)

Tett et al. (2000) used an "optimal detection methodology" with global climate model simulations to try and match the observational data.  The inputs into the model included measurements of GHGs in the atmosphere, aerosols from volcanic eruptions, solar irradiance, human aerosol emissions, and atmospheric ozone changes (ozone is another greenhouse gas).

Tett et al. applied their model to global surface temperatures from 1897 to 1997.  Their best estimate matched the overall global warming during this period very well; however, it underestimated the warming from 1897 to 1947, and overestimated the warming from 1947 to 1997.  For this reason, during the most recent 50 year period in their study (shown in dark blue in Figure 1), the sum of their natural and human global warming contributions is larger than 100%, since their model shows more warming than observed over that period.  Over both the 50 and 100 year timeframes, Tett et al. estimated that natural factors have had a slight net cooling effect, and thus human factors have caused more than 100% of the observed global warming.

Meehl et al. (2004)

Meehl et al. 2004 used a similar approach to Tett et al., running global climate model simulations using various combinations of the different main factors which influence global temperatures (GHGs, solar activity, volcanic aerosols, human aerosols, and ozone), and comparing the results to the temperature data from 1890 to 2000.  They found that natural factors could account for most of the warming from 1910 to 1940, but simply could not account for the global warming we've experienced since the mid-20th Century.

Meehl et al. estimated that approximately 80% of the global warming from 1890 to 2000 was due to human effects.  Over the most recent 50 years in their study (1950-2000), natural effects combined for a net cooling, and thus like Tett et al., Meehl et al. concluded that human caused more than 100% of the global warming over that period.  Over the past 25 years, nearly 100% of the warming is due to humans, in their estimate.

Stone et al. (2007)

Stone et al. actually published two studies in 2007.  The first paper examined a set of 62 climate model simulation runs for the time period of 1940 to 2080 (the Dutch Meteorological Institute's "Challenge Project").  These simulations utilized measurements of GHGs, volcanic aerosols, human aerosols, and solar activity from 1940 to 2005, similar to the Tett and Meehl studies discussed above, and then used projected future emissions from the Intergovernmental Panel on Climate Change (IPCC) to project future global warming.  Whereas Tett and Meehl examined the climate response to each individual factor (and/or combinaton of factors), Stone compared these 62 climate model runs to a series of energy balance models, each representing the climate's response to a different effect.  Over the 60 year period, Stone et al. estimated that humans caused close to 100% of the observed warming, and the natural factors had a net negative effect.  As with Stott, their model did not fit the data perfectly, though they had the opposite result, underestimating the observed warming.

In their second 2007 paper, Stone et al. updated the results from their first paper by including more climate models and more up-to-date data, and examining the timeframe of 1901 to 2005.  Over that full 104-year period, Stone et al. estimated that humans and natural effects had each contributed to approximately half of the observed warming.  Greenhouse gases contributed to 100% of the observed warming, but half of that effect was offset by the cooling effect of human aerosol emissions.  They estimated that solar and volcanic activity were responsible for 37% and 13% of the warming, respectively.

Lean and Rind (2008)

Lean and Rind 2008 used more of a statistical approach than these previous studies, using a multiple linear regression analysis.  In this approach, Lean and Rind used measurements of solar, volcanic, and human influences, as well as ENSO, and statistically matched them to the observational temperature data to achieve the best fit.  Analyzing what is left over after summing the various contributions shows whether the most significant contributions are being considered.

LR08 did this over various timeframes, and found that from 1889 to 2006, humans caused nearly 80% of the observed warming, versus approximately 12% from natural effects.  As with the previous studies discussed, this doesn't add up to exactly 100% because the statistical fit is not perfect, and not every effect on global temperature was taken into consideration.  From both 1955 and 1979 to 2005, they estimated that humans have caused close to 100% of the observed warming.

Stott et al. (2010)

Stott et al. (S10) used a somewhat similar approach to LR08, but they used their statistical multiple linear regression results to constrain simulations from five different climate models.  S10 calculated regression coefficients for greenhouse gases, other human effects (dominated by aerosols), and natural effects (solar and volcanic), and estimated how much warming each caused over the 20th Century.  The average of the five models put the human contribution at 86% of the observed warming, and greenhouse gases at 138%, with a very small natural contribution.

Stott et al. also corrobarated their results by looking not only at global, but also regional climate changes by reviewing the body of scientific literature.  They note that human influences have been detected in changes in local temperatures, precipitation changes, atmospheric humidity, drought, Arctic ice decline, extreme heat events, ocean heat and salinity changes, and a number of other regional climate impacts.

Huber and Knutti (2011)

Huber and Knutti 2011 implemented a very interesting approach in their study, utilizing the principle of conservation of energy for the global energy budget to quantify the various contributions to the observed global warming from 1850 and 1950 to the 2000s.  Huber and Knutti took the estimated global heat content increase since 1850, calculated how much of the increase is due to various estimated radiative forcings, and partition the increase between increasing ocean heat content and outgoing longwave radiation.  More than 85% of the global heat uptake has gone into the oceans, so by including this data, their study is particularly robust.

Huber and Knutti estimate that since 1850 and 1950, approximately 75% and 100% of the observed global warming is due to human influences, respectively.

Foster and Rahmstorf (2011)

Foster and Rahmstorf (2011; FR11) implemented a very similar statistical approach to that in Lean and Rind (2008).  The main difference is that FR11 examined five different temperature data sets, including satellites, and only looked at the data from 1979 to 2010 (the satellite temperature record begins in 1979).  They also limited their analysis to the three main natural influences on global temperatures - solar and volcanic activity, and ENSO.  What remains once those three effects are filtered out is predominantly, but not entirely due to human effects.  For our purposes, we will classify this remainder as the human contribution, since FR11 removed the three largest natural effects.

Using the temperature data from the British Hadley Centre (which was used by LR08, and is the most frequently-used temperature data set in these studies), FR11 found that the three natural effects in their analysis exerted a small net cooling effect from 1979 to 2010, and therefore the leftover influence, which is predominantly due to human effects, is responsible for more than 100% of the oberved global warming over that timeframe.

One key aspect of this type of study is that it makes no assumptions about various possible solar effects on global temperatures.  Any solar effect (either direct or indirect) which is correlated to solar activity (i.e. solar irradiance, solar magnetic field [and thus galactic cosmic rays], ultraviolet [UV] radiation, etc.) is accounted for in the linear regression.  Both Lean and Rind and Foster and Rahmstorf found that solar activity has played a very small role in the observed global warming.

Gillett et al. (2012)

Similar to S10, Gillett et al. applied a statistical multiple linear regression approach to a climate model - the second generation Canadian Earth System Model (CanESM2).  They used data for human greenhouse gas and aerosol emissions, land use changes, solar activity, ozone, and volcanic aerosol emissions.  In their attribution they grouped some of the effects together into 'natural', 'greenhouse gas', and 'other'.  The authors estimated the effects of each over three timeframes: 1851-2010, 1951-2000, and 1961-2010.  For their attributions over the most recent 50 years, we took the average of the latter two, and used their 'other' category as an estimate for the influence of human aerosol emissions (which will result in somewhat of an underestimate, since most 'other' effects are in the warming direction).

Gillett et al. estimated that over both timeframes, humans are responsible for greater than 100% of the observed warming.

Human-Caused Global Warming Consensus

The agreement between these studies using a variety of different methods and approaches is quite remarkable.  Every study concluded that over the most recent 100-150 year period examined, humans are responsible for at least 50% of the observed warming, and most estimates put the human contribution between 75 and 90% over that period (Figure 2).  Over the most recent 25-65 years, every study put the human contribution at a minimum of 98%, and most put it at well above 100%, because natural factors have probably had a small net cooling effect over recent decades (Figures 3 and 4).

Additionally, in every study over every timeframe examined, the two largest factors influencing global temperatures were human-caused: (1) GHGs, followed by (2) human aerosol emissions.  This is a dangerous situation because as we clean our air and reduce our SO2 emissions, their cooling effect will dissipate, revealing more of the underlying GHG-caused global warming trend.  Note that not all studies broke out the effects the same way (i.e. only examining 'natural' and not solar or volcanic effects individually), which is the reason some bars appear to be missing from Figures 2 to 4.

100-150

Figure 2: Percent contributions of various effects to the observed global surface warming over the past 100-150 years according to Tett et al. 2000 (T00, dark blue), Meehl et al. 2004 (M04, red), Stone et al. 2007 (S07, green), Lean and Rind 2008 (LR08, purple), Stott et al. 2010 (S10, gray), Huber and Knutti 2011 (HR11, light blue), and Gillett et al. 2012 (G12, orange).

50-65 years

Figure 3: Percent contributions of various effects to the observed global surface warming over the past 50-65 years according to Tett et al. 2000 (T00, dark blue), Meehl et al. 2004 (M04, red), Stone et al. 2007 (S07, green), Lean and Rind 2008 (LR08, purple), Huber and Knutti 2011 (HK11, light blue), and Gillett et al. 2012 (G12, orange).

25-30

Figure 4: Percent contributions of various effects to the observed global surface warming over the past 25-30 years according to Meehl et al. 2004 (M04, red), Lean and Rind 2008 (LR08, purple), and Foster and Rahmstorf 2011 (FR11, green).

There was a period of warming between 1910 and 1940 which was predominantly caused by increasing solar activity and an extended period of low volcanic activity, with some contribution by human effects.  However, since mid-century, solar activity has been flat, there has been moderate volcanic activity, and ENSO has had little net impact on global temperatures.  All the while GHGs kept increasing, and became the dominant effect on global temperature changes, as Figures 3 and 4 illustrate.

A wide variety of statistical and physical approaches all arrived at the same conclusion: that humans are the dominant cause of the global warming over the past century, and particularly over the past 50 years.  This robust scientitic evidence is why there is a consensus amongst scientific experts that humans are the dominant cause of global warming.

Note: this post has been incorporated into the rebuttals to It's not us (Advanced), Increasing CO2 has little to no effect (Advanced), It's the sun (Intermediate and Advanced), and A drop in volcanic activity caused warming.

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Comments 51 to 76 out of 76:

  1. muoncounter#49: I have checked 2 links you had mentioned, and all records point ultimately lead to [Ramaswamy et al., 2001 - you claimed as "Chapter 6 of the 2001 TAR, which is somewhat out of date" - http://www.ipcc.ch/ipccreports/tar/wg1/pdf/TAR-06.PDF] only, which starts with the assumption. . I think starting with assumption, no one, yes no one need to prove the assumption, but safely can use the "circularity" logic as mentioned in #38
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  2. Patonomics: “Climate models are mathematical representations of the climate system, expressed as computer codes and run on powerful computers. One source of confidence in models comes from the fact that model fundamentals are based on established physical laws, such as conservation of mass, energy and momentum, along with a wealth of observations.” Source: “Frequently Asked Question 8.1: How Reliable Are the Models Used to Make Projections of Future Climate Change?”, Working Group 1: The Physical Science Basis, UN IPPC Click here to access this document,
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  3. DSL#50: I do not claim to be Climate Scientist or Climate Professional and neither likely to be one in near future. I am looking for support if someone already validate in a form "any science validate itself non-confusingly (with out circular logic to depend)". I have my own profession to look after. My present interest is to check only if there are substantial Deterministic validation or not. I am not going to read and read in litterateurs and compete with those who are into full time Climate Scientist as their job. After reading your comments I recall about, Italian physicist Galileo Galilei, when he questioned traditional wisdom of majority, it infuriated the majority who are connected by consensus with "strong theoretical evidence" based on assumptions! I hope I have not infuriate you. That is not my intention or remotely target and I positively hope you do not have similar target either. I like your philosophical response for a needed scientific Validity on curiosity. I am not sure if someone might have better understanding about science with your philosophical response!
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  4. patonomics#52: Concepts of radiative forcing pre-date the IPCC report of 2001. Keep in mind that IPCC documents are merely reviews of the state of the science at the time of issue - the basic research was done by others. See for example Hansen et al 1997. The only thing circular here is your persistent conviction that you and you alone are correct. You've been referred to numerous reference documents; the evidence for the theory that you're trying to dispute is readily available.
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  5. John Hartz#53: I strongly expect it ("Climate models are mathematical representations of the climate system") should be like that, so I could not comprehend why none could produce cause and effect relationship equation as yet in this forum (contrary I am getting everything other than that equation). In establishing science, scientist first publish a research article clearly depicting their formula, their all assumptions and then validate to claim why their equation is deterministic. But what I get so far is not that clarity but pointer towards some models, which when it old is not good enough, but new models are better. You may agree mostly people get Nobel Prize after scientific community can validate their science over decades, can anyone explain why in AGW of CS (Climate Science), old models need not to be validated, telling its outdated, but all people are expected to BELIEVE in current models (that's not validated conclusively and only evolving, and still expected to think science of AGW is deterministic)?
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    Moderator Response:

    [DB] Models are not the topic of this thread,  For a further discussion of those, see either the How do Climate Models Work? thread or the Models are unreliable thread.  Please continue any discussion of models there, not here.

    Furthermore, this thread is A Comprehensive Review of the Causes of Global Warming.  Discussion of the philosophy of science on this thread have now run their course.  As no meaningful fruit has arisen, it is now off-topic on this thread and subsequent pursuit of this topic will receive further, more severe moderation.

  6. Patonomics - I have read your comments so far on this thread - your philosophy seems rooted in the Sophists of the ancient Greeks (although I mean the modern definition of sophistry). Also - if you are now invoking the (false) equivalence of climate "Skeptics" with Galileo (being a skeptic of an earth-centric universe) - there are two problems - 1) the entire body of science has had over 500 years to mature and expand - so basic misunderstandings, like the role of CO2 in the climate are very, very rare. Indeed, can you point to 3 cases of a basic misunderstanding about science that happened in the entire 20th century? and 2) Galileo himself built his theories upon two pillars - the body of science and his own observations. Both the body of science and observations now support the AGW theory (indeed even those vaunted 3% disagree dramatically on questions of where the warming is coming from (very few actual scientists claim no warming), where it is going, how fast, etc. ) So there isn't really an opportunity for a credible skeptic to invoke Galileo as a counter to the widespread (overwhelming) body of scientific evidence that the world is warming and man is to blame.
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  7. muoncounter#55: about your claim "The only thing circular here is your persistent conviction that you and you alone are correct." - is not true. I am looking for validation from AGW claiming community, when someone claims to AGW be deterministic. If you think I am talking about myself, "and not about validation of science of AGW", then we are not in same frequency. And there is no point to discuss further. I am only looking for validation, and validation alone, if there are any. Else I do not need anything from anyone!
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  8. actually thoughtful#57: You are entitled to hold your own thoughts, but that does NOT change my question about validation!
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  9. patonomics - My apologies, this may be a language issue, but I cannot parse your last post. The "Galileo Gambit only suffices if you are correct. The mass of evidence supports anthropogenic global warming - if you disagree, you need to provide a better answer, which you have (so far) notably failed to do. Global warming via human generated greenhouse gases fits the last 150 years of spectroscopy, all the observations, multiple fingerprints, etc. What alternative do you point to? If any? Or are you simply presenting the argument from incredulity, which is a logical fallacy?
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  10. KR#60: What I tried to communicate is science needs validation and not assumption. I do NOT and can NOT equate myself with "Galileo". "mass of evidence supports anthropogenic global warming" - I am just asking if it is 1) validated or 2) derived from assumption, or from 3) theory (based on assumption)? If AGW is validated truth, why not its quantitative (I expect the relationship must be deterministic in quantitative level) form is presented in a equation of temp as dependent variable of human created co2. Once I get validation document it will SILENCE my Q. Is not that easy to and many other who claim "The mass of evidence supports anthropogenic global warming" ?
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  11. patonomics - it is notable that you have no 20th century examples of Galileo, nor can you produce any counters to the overwhelming evidence in support of AGW. I hope you will take the time to think about the implications of those two items. It appears your validation is already at hand. Your task is simply to understand what the evidence tells us - that world is warming, and man is to blame.
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  12. Moderator Response#56: I got your msg ["subsequent pursuit of this topic will receive further, more severe moderation"]. I will not bother you any more. Thank you for your clear communication.
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    Response:

    [DB] Unfortunately, there are no posts at Skeptical Science directly focus on the philosophy of science.  You are welcome to peruse any/all of the 4,700+ comment threads here at SkS dealing with all aspects of climate science and may place on-topic comments on any of them.

    Simply use the Search function in the Upper Left of every page to locate those more appropriate threads.

  13. Patonomics - You are asking for an equation and we are responding by saying - you don't need an equation when the evidence is directly in front of you. However, here is a simple equation. The hypothesis is that it is warmer now than in 1975. this can be expressed in the logical equation: If Tn>Tt, global warming is occurring (you recognize, of course that this is simplified as necessary to present it on a blog site) Where Tn is Temperature now, and Tt is Temperature then (as I said- keep it simple). Thus you have your validation equation, supported, not by models, but observable reality. And of course, this was predicted by Arrhenius in 1896, so the science has been tested almost as long as old Galileo (by which I mean you can measure in the 100 year increments). If this does not meet your equation requirements, perhaps you can be both more specific and more succinct?
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  14. patonomics: You've been pointed to any number of 'validation documents' and yet you ignore those pointers. #61: "I am just asking if it is 1) validated or 2) derived from assumption, or from 3) theory (based on assumption)? " That is entirely circular. The theory is valid (it is called 'physics'), the data validate the theory. The only one making assumptions is you, as you have built a case on a single sentence from a thousand-plus page summary document. And in #54: "I am not going to read and read in litterateurs and compete with those who are into full time Climate Scientist" If you don't want to read, you don't want to learn - or even have your preconceived notions (a 'deterministic equation') challenged. I note that you have not responded to several comments showing the irrelevancy of that search. We must conclude that your 'questions' here are merely rhetorical; no one has time to play that game.
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  15. I see that patanomics (@63) has got the very "clear communication" from the moderator. I expect him therefore to reopen this discussion in a thread in which it is on topic, as that was the very clear suggestion by the moderator. Something about the wording of patanomics response, however, suggests to me that he is trying to pretend that a requirement that he comply withe the comments policy is actually censorship, when it is no such thing. I hope I am wrong.
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  16. patonomics - I would point you towards the simplified RealCliate overview, as well as The Discovery of Global Warming. Multiple observations, multiple reinforcing fingerprints of anthropogenic warming (as opposed to solar, cosmic ray, leprechauns, etc.), basics in pure science such as spectroscopy, >120 years of simple physics pointing to the increased greenhouse effect, on and on and ... If you want a simple equation (and apparently you are looking for a shrink-wrapped simplification), I would suggest this. As inputs, look at the changes in radiation to space at the top of the atmosphere (TOA) over the satellite era, demonstrating reductions from the pure black-body spectra to a less efficient (in terms of energy radiated based on temperature) emissivity due to increased greenhouse gases. Less energy radiated at a particular temperature, thus higher temperatures to radiate away what the sun inputs to the climate system - it doesn't get any simpler than that.
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  17. #61: You request validation, but what do you wish validation of? 1: That the Earth's temperature is rising, according to all major temperature records? 2: That the concentration of CO2 in the atmosphere continues to rise rapidly, and that the CO2 increase is isotopically identifiable as being fossil fuel-derived? 3: The fundamental theoretical and experimental basis for CO2, water vapour and some other gases being radiatively active (see Spencer Weart for a history going back 150 years)? 4: The direct observations of the CO2 greenhouse effect (e.g. Harries et al 2001, Philipona)? 5: The observations that the temperature rise is consistent with the enhanced greenhouse effect (nights warming faster than days, stratosphere cooling etc). It is inconsistent with a warming from other sources. Do you not trust the above observations or the century-old theoretical basis? If not, why not? What more validation do you need?
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  18. DSL @50, I second your suggestion of Spencer Weart's book. But this is all off topic. If it was patonomics's goal to derail the thread, s/he certainly is trying very hard. They are also, despite trying to create that impression, not amendable to reason or compelling evidence. The independent research papers cited provide a very consistent and coherent picture, and that is clearly causing some angst amongst the "skeptics". If people want to debate the philosophy behind AGW, or other aspects then please take them to the relevant threads. This thread is to discuss the "review the results of these various studies, and a few others which we have not previously examined, to see what the scientific literature and data have to say about exactly what is causing global warming.". So can we stick to that please. Surely is not to much to ask?
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  19. Patonic built an off-topic distraction about the philosophy of science. He is poorly versed in AGW, but very well versed in philosophy 101 and knowing how to manipulate an internet thread. Basically he trashed a very important topic, and redirected it to where what he knows is more important than what others know. Example- the TAR is out-of-date. ... AR4 states outright that the definition of radiative forcing from the TAR is retained: http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2s2-2.html He walked right by the best suggestion - go to the link and start with 'the Discovery of Global Warming'. He ignored the response where he could study a survey of CO2 properties.
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  20. The request of a set of equation for validation of the theory is disingenuous. Equations from quantum theory are needed to calculate the radiative forcing of CO2. The radiative forcing is a direct consequence of quantum laws, those laws seemingly so dear to Patonomics. The only way that heat will not build up in the atmosphere with added GH is if quantum laws somehow do not hold. Not likely. These calculations have been done by LBLRTM and MODTRAN. The results of the calculations closely match observations. Then, there is all the fluid dynamics equations necessary to model atmospheric circulation, and ocean circulation for AOGCMs. And then there is more, as climate science is complex. That is simply too much to list in a setting like this. It would require an entire team with varied areas of expertise. However, it is in fact possible to do so. It's just not really worth bothering; what would the point? to make a point. Feh... I affirm that quantum theory alone is enough to show witout any doubt whatsoever that adding CO2 to the atmosphere will increase the heat content of the whole atmoshere/ocean system. The only possibility that it would be otherwise would reside with the existence, as yet uncovered, of a mechanism that would allow the extra heat to be radiated out to space immediately. Lindzen's hypothesis has not panned out so well. I find Patonomics' contribution so far to be of little value and I would encourage all to get back to the topic (I know, I just indulge for a few paragraphs myself).
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  21. Well the most basic equations, verifiable from satellite and ground measurements would be the RTEs, for which Ramanathan and Coakley 1978 would be the starting point.
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  22. Don't you see? SkS has failed to provide a summary of all the research/measurements/math/physics/and theory in one paragraph. Since you are unable or unwilling to do so you must be hiding something behind all that complicated math and all those long boring papers. Now that his inconvenient and probing questions have made the AGW Team uncomfortable he has been silenced! The only logical conclusion is that he has gotten too close to uncovering the Man Behind the Curtain. /sarcasm
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  23. pbjamm.... Okay, that was just a little too close to real. (@73) You can't imagine how many times I've read virtually those exact statements online, only with no sarcasm.
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  24. I have to make an apology: I am the friend who pointed Patonomics to SkS and the possibility to discuss AGW here, after I had exhausted my efforts to make him understand the concept. I also had already provided him with copies of or links to a lot of up to date literature and discussions, on climate models, trends, the BEST study, Arctic ice melt, etc etc, whatever i could find including Principles of Planetary Climate. Only having a PhD in medicine, some odd 30 years in science and having read climate science literature for the last 20 yrs I thought that maybe I lacked clarity in my arguments.... Thanks anyway to all of you who took time to engage in the debate.
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  25. Zeboo - no need for an apology. Your friend Patonomics is engaging in a form of denial. That's not a condition we can cure. Be nice if he didn't write in riddles too, it impresses no one here. State things plainly - if you can't maybe you don't know what you're on about?
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  26. Dana’s OP has been summarized by RP Siegel in “What Are the Real Causes of Global Warming?” posted (Jan 25, 2012) on Triple Pundit. Sigel’s insightful opening paragraph: “The folks at Skeptical Science have put together a review of various scientific investigations into the causes of global warming, in hopes of coming up with a definitive answer. This seems like a good time to do this, in the midst of Republican primary season, as the various candidates try to one-up each other on bashing the science in lieu of what their supporters would prefer to hear.”
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  27. User LRDT has asked about the human attribution of the causes of global warming and climate change.  Given this:

    Causes of AGW

     

    And this:

    Causes of AGW

     

    Yields this, from the OP above:

    Causes of AGW

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  28. It is also worth noting that in political debates, finding a middle ground is often in the way forward. However, science doesnt go for middle ground much. You cant try and postulate that there are fictional sources of warming for which there is no evidence. If you want to excuse humans then you need to provide evidence for other causes that dont violate first law thermodynamics. For example, you cant say the warming is coming from the oceans on some "natural cycle" while the oceans continue to heat. You can explain short term heating (eg El Nino) from ocean/atmosphere exchange (ocean heat content drops) but not long term.

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