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Matt Ridley - Wired for Lukewarm Catastrophe

Posted on 29 August 2012 by dana1981

Note: this post has been quoted in the November 2012 issue of WIRED magazine.

Matt Ridley has an article published in the September 2012 issue of WIRED magazine, which appears to be their cover story this month.  The article is full of misleading and inaccurate claims, logical fallacies, and quite frankly is little more than an attack on environmental concerns in general.  Not surprisingly, it was republished and hailed by the usual climate denial enablers.  The article essentially claims that every environmental concern over the past half century can be boiled down to 'alarmism'.

For example, Ridley pooh-poohs the adverse health effects of DDT, downplays the role of chlorofluorocarbons (CFCs) in ozone depletion, the health risks associated with air pollution, and so on.  The general theme of the article is that because these other environmental concerns did not result in catastrophic consequences, environmental concerns in general can be considered overblown alarmism.

Now, there is of course a glaring logical fallacy in this argument - we took action to address all of these prior environmental concerns.  We phased out the use of DDT and CFCs, passed Clean Air Acts to reduce air pollution, etc.  In fact, we recommend that anyone reading Ridley's article first put on a head vise, because he manages to undercut the premise of his own argument by making this very point:

"By the 1970s the focus of chemical concern had shifted to air pollution....driven partly by regulation and partly by innovation, both of which dramatically cut the pollution coming from car exhaust and smokestacks, ambient air quality improved dramatically in many cities in the developed world over the following few decades."

You might wonder how Ridley can make the argument that these prior environmental concerns were overblown because they did not have catastrophic results, when he himself admits that we took steps to stem their adverse impacts.  Please keep your head vise on while you try to figure out the answer to that question, and if you do figure it out, please let us know.  Chris Goodall debunks many of the claims Ridley makes with regards to past environmental threats in a good post at Carbon Commentary.

By this point you have probably guessed where Ridley's article ultimately ends up - claiming that concerns about climate change are overblown because these previous environmental concerns were supposedly overblown.  Ridley claims that the consequences of climate change probably won't be all that bad, and that based on the lessons of these previous environmental concerns (you know, the ones where we listened to the scientific experts and addressed the problem), we should start listening to the "lukewarmers", whose climate-related myths Ridley begins to reel off one by one.

Do "Lukewarmers" Ignore Scientific Data?

Here is how Ridley begins his discussion about what he calls "lukewarmers":

"We hardly ever allow the moderate “lukewarmers” a voice: those who suspect that the net positive feedbacks from water vapor in the atmosphere are low, so that we face only 1 to 2 degrees Celsius of warming this century"

It's rather strange that Ridley claims that we hardly ever hear from this group, considering how frequently the few climate scientist "lukewarmers" (i.e. Richard Lindzen and John Christy) are published in the mainstream media or invited to testify before Congress.  In reality the "lukewarmers" are disproportionately over-represented, particularly in the mainstream media.

Regardless, at this point we actually have a good amount of empirical data to measure the water vapor feedback.  For example see our discussion here, a list of relevant scientific papers here, and a new paper by Dessler (2012) here.  The literature consistently shows that the water vapor feedback is a positive strong one, as we expect.  Dessler (2012) described observational data from 2000 through 2010:

"climate variations were also amplified by a strong positive water vapor feedback (~ +1.2 W/m2/K)"

We are left wondering why "lukewarmers" supposedly suspect that the water vapor feedback is a weak one when the empirical data clearly indicate otherwise.  Ridley suggests that "lukewarmers" also think we only face 1-2°C warming this century, but under what emissions scenario does this belief apply?  For example, if we reach an atmospheric CO2 level of 900 ppm by 2100 (which is entirely plausible if we follow Ridley's advice and don't worry about global warming or take action to mitigate it), a resulting 2°C warming over the next century (~2.8°C since pre-industrial times) would correspond to a climate sensitivity of only about 1.6°C for doubled CO2. 

Do "lukewarmers" really believe that climate sensitivity cannot be higher than 1.6°C when the body of scientific literature puts the likely range between 2°C and 4.5°C for doubled CO2 (Figure 1)?

Various estimates of climate sensitivity

Figure 1: Distributions and ranges for climate sensitivity from different lines of evidence. The circle indicates the most likely value. The thin colored bars indicate very likely value (more than 90% probability). The thicker colored bars indicate likely values (more than 66% probability). Dashed lines indicate no robust constraint on an upper bound. The IPCC likely range (2 to 4.5°C) and most likely value (3°C) are indicated by the vertical grey bar and black line, respectively.  Adapted from Knutti and Hegerl (2008).

Lukewarm Greenland

According to Ridley, "lukewarmers" also believe

"that the Greenland ice sheet may melt but no faster than its current rate of less than 1 percent per century"

The problem with this particular statement is that the Greenland ice sheet is probably already melting faster than when Ridley wrote it (Figure 2).

greenland ice melt

Figure 2: Greenland ice mass anomaly - deviation from the average ice mass over the 2002 to 2010 period. Black line shows monthly values. Orange line shows long-term trend (John Wahr).

The Greenland ice sheet mass declined by approximately 250 billion tons per year from 2003 to 2009 according to Gravity Recovery and Climate Experiment (GRACE) data (Schrama and Wouters 2011), and the decline is accelerating by approximately 30 billion tons per year. 

We know Ridley expects global warming to accelerate, because we saw 0.8°C surface warming over the past century, whereas he expects 1-2°C warming over the next century.  So for "lukewarmers" to believe the current rate of Greenland ice sheet mass loss will remain steady over the next century, somehow the current accelerating mass loss will have to stop despite accelerating global warming.  Try explaining that one.

Lukewarm Agriculture

The next thing Ridley claims "lukewarmers" believe is

"that net increases in rainfall (and carbon dioxide concentration) may improve agricultural productivity"

It's true that some places will see increased rainfall while others will see a decrease.  Perhaps we should consult projections of future drought (via the Palmer Drought Severity Index [PDSI]) to determine how agricultural productivity might fare in a warmer world, from Dai (2010) (Figure 3).

pdsi dai

Figure 3: the potential for future PDSI worldwide over the decades indicated, based on current projections of future greenhouse gas emissions (Source)

This is not a pretty picture (except for the nice colors, of course).  By the 2030s most of the United States southern Europe, southeast Asia, northern and southern Africa, eastern Australia, etc. will regularly face droughts around the same severity as those which seriously adversely affected American agricultural productivity this summer.  Northern Canada and Siberia may become suitable for agricultural productivity - do we want to move all of our crops to those regions?

Low Lukewarm Standards and High Risk

Ridley also notes that "ecosystems have survived sudden temperature lurches before."  This is true, but is mere survival the standard we want to set for ourselves and the ecosystems on which we rely?  Moreover, there have been mass extinction events during which ecosystems did not survive sudden temperature lurches.  In fact, there is evidence we may be entering the sixth such mass extinction event.  Do we really want to take that risk under Ridley's reassurance that ecosystems might be able to survive it?

It is perhaps not surprising that Ridley advocates this high risk approach.  As Andy S previously discussed, Ridley  was the non-executive Chairman of Northern Rock, a British bank that, in 2007, was the first in over a century and a half to experience a run on its deposits.  The bank had allowed itself to become extremely over-leveraged, with debts more than 50 times its shareholder common equity.  Ultimately Northern Rock was bailed out, borrowing £3 billion from the Bank of England over the span of a few days in 2007. 

Unfortunately if Ridley is wrong in his foolhardy approach toward climate risk, there is nobody to bail us out when the climate goes awry.

Lukewarm Strawmen

Finally, Ridley says that "lukewarmers" believe

"that adaptation to gradual change may be both cheaper and less ecologically damaging than a rapid and brutal decision to give up fossil fuels cold turkey."

This is of course a strawman argument - nobody suggests that we should immediately cease burning all fossil fuels.  The transition away from fossil fuels will be a slow and difficult one, but we must do it as quickly as possible, because time is running out.  Additionally, the benefits of the solutions which have actually been proposed (i.e. carbon pricing) exceed the costs several times over (Figure 4).

Figure 4:  Approximate costs of climate action (green) and inaction (red) in 2100 and 2200. Sources: German Institute for Economic Research and Watkiss et al. 2005

False Equivalence and Other Logical Fallacies

In general, Ridley's argument suffers from the fallacy of false equivalence.  For example, he equally criticizes concerns about ozone depletion and air pollution (real environmental hazards that caused measurable damage which we addressed by reducing emissions of the responsible substances) with predictions of December 2012 apocalypse (pure fiction) and concerns about climate change (a very real and very large threat which we have yet to address).

Ridley's dismissal of the climate change threat because past threats have not resulted in catastrophe is entirely illogical.  Consider a doctor treating a patient for a potentially deadly infection.  The doctor prescribes antibiotics, which successfully treat the infection, and the patient survives.  A few years later, the doctor diagonses the same patient with cancer.  If Ridley were the patient in this scenario, he would claim that the cancer is no threat because the infection did not kill him. 

Lukewarm Arguments at Best

Ridley has not painted those he describes as "lukewarmers" in a flattering light in this article.  Apparently they believe that climate change cannot possibly result in catastrophic consequences because no environmetal concern in modern times has resulted in catastrophe, ignoring the fact that we have taken steps to address all prior environmental threats.  "Lukewarmers" also apparently do not believe that the water vapor feedback is strongly positive, even though that is what the scientific data indicates, or that climate sensitivity could be within the likely range of values from the scientific literature.  They think that the Greenland ice sheet decline - which is already accelerating - will not accelerate.  They think agricultural productivity will increase despite measurements and projections of increasing drought.  And instead of considering serious proposals to mitigate global warming, they claim that we 'alarmists' want to immediately cease burning all fossil fuels.

As we noted when discussing a recent Wall Street Journal article from some other climate contrarians, the beauty of publishing articles in the mainstream media is that unlike in the scientific literature, you are not expected to support your assertions.  As a result, Ridley is able to make a mockery of all previous environmental concerns by rewriting history.  Ridley also manages to mostly ignore the fact that the reason these past environmental threats did not result in very bad consequences is that we took action to prevent that from happening (except when he undermines the entire premise of his article by making that very point). 

The exact same thing is true of climate change - if we take action to mitigate the problem, we can avoid catastrophic consequences.  We can also address the problem in a way that results in a net benefit not just for global ecosystems, but even for human economies (see this NY Times piece for a good discussion on the subject).  Unfortunately Ridley does not offer any constructive discussion about how we should address the problem; instead he continues his caricature of alarmist environmentalists by claiming that the only proposed solution to the problem involves immediately ceasing all fossil fuel use.  It is unfortunate that WIRED prominently featured such a counterfactual and unconstructive article.

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Comments 51 to 83 out of 83:

  1. Bernard J @ 49: Can you please clarify your point regarding the geometry of moving north? Does this presuppose an equivalent loss of farm land on the southern end? Do you have any links to scientific papers, which have evaluated the relative greenhouse gas release from soil vs. that absorbed by expansion of the boreal forest?
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  2. re: 48 Smith Yes, certainly there may be prairie extension. Sadly, some of that might be assisted by bark beetles chewing through Alberta and working their way across the Boreal forest. I simply mentioned the Shield because I've more than once encountered people simply looking at a map and thinking there is a lot of land up North where agriculture can move without thinking in the slightest about the nature of the soils, rainfall, etc. Usually, people saying this have ~zero experience with farming. I wouldn't pretend to have seen detailed studies of Northwood movement of agriculture, although since we ski every year at Big White, I'm familiar with the Northward spread of viticulture in the Okanagan region. Anyway, if anyone has serious studies of Canadian soils and their suitability for framing assuming a warmer climate, they would be interesting to see.
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  3. Sphaerica @50: scaddenp @ 36, has, I suspect, correctly come to the point. Joel Upchurch appears to have confused climate forcings with feedbacks (inadvertently, I am sure) and appears to be accusing the IPCC of being in error on this point, apparently on the basis of your statements in #26. Hope that makes things clear (as mud).
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  4. KR @ 45 I looked at the graph and it actually looks like a good fit for real world data. Here is my latest graph: CO2 1958-2012 Exponential Fit R-Squared is .98 and visually the curve fits within the seasonal variation in CO2, but that isn't the important part. the article you cited has an interesting graph. Tamino CO2 You will notice that C02 follows a nice smooth curve since 1998, except for the last few years which is probably the recession. I have a graph for 2000-2012 CO2 from 2000-2012 That gives 628PPM by 2100. I can exclude the recession data by graphing just 1998 to 2006 if you like. C02 Spreadsheet Or you can download my spreadsheet and graph you own curve. Saying the data isn't exponential isn't very useful. The curve fitting routines can get an excellent fit for almost any data, unless you think there will be a singularity. What curve do you expect future C02 growth to follow?
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  5. Bernard J. @46. I'm sorry, but without the supporting data all you have done is draw a pretty picture that you are asking us to take on faith. I have a math degree, so I don't think I will swoon if post the supporting data.
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  6. KR @ 47 An exponential can be fit to almost any data. If you don't think it is exponential, then explain what curve you think fits the actual data better and the scientific justification for the curve is
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  7. Joel, #54, you arrived on this thread (#21) by putting a naive linear fit through 30 years of temperature data. You followed that up (#23) by making a variety of naive proclamations about the relationship between CO2 and temperature (essentially assuming that CO2 was the only forcing, that there were no feedbacks, and that the response to CO2's forcing would be instantaneous). All those assumptions are wrong, and affect your conclusions. In #28 you demonstrate particularly poor statistical treatment of data by putting a linear trend through the CO2 concetration dataset that is clearly accelerating over time, ignoring assessment of the residuals (for example such as Tamino's). All the while you seem to be claiming a rigid, linear fit and extrapolation with no assessment of processes such as feedbacks or the time delay due to equilibration of the energy balance (which is why we talk of transient and equilibrium climate sensitivity, look it up). Yet somehow you expect us to think you're onto something here? The IPCC's scenarios (you do realise that emissions cannot be simply extrapolated, don't you?), are here. You'll note that the A1FI, A2 and A1B scenarios all cross 700ppm, A1FI and A2 cross 800ppm by 2100. The IPCC's emissions scenarios have considerably greater justification than any of the naive curve fits you've managed so far. Tamino didn't say the CO2 data "wasn't exponential", he showed it was "greater than exponential", and he showed this with considerably more rigor than you have managed to date.
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  8. 628ppm by 2100 would translate into around 2.2K of warming cf current day given best estimates of climate sensitivity though you would not expect all of that to realized by 2100.
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  9. Joel Upchurch, this entire conversation reminds me of learned discussions of how angels select parners for pinhead dancing. You are taking a short record and trying to project growth 100 years into the future without any consideration of the relevant physical factors. It may be an interesting class room exercise, but has no bearing on the real world. Treated abstractly, there three major variables determining CO2 emissions. The three are population, per capita GDP, and carbon emissions per unit of GDP (carbon intensity). Taking just growth in GDP, if it continues at the historical average of about 3% per annum, then by 2100, emissions will have increased by a factor of 12 over current levels. That by itself is more than enough to increase atmospheric concentration of CO2 to 900 ppmv or more. On top of that is an expected growth of world population by 40% in the next 40 years. That does not simply add 40% to the expected emissions growth from GDP growth because most of the population growth will be in low GDP nations. Never-the-less, it shows that 900 ppmv by 2100 is an underestimate of likely CO2 concentration unless we significantly reduce emissions intensity. Just to maintain constant CO2 emissions, and hence a linear increase in CO2 concentration, that means we require a reduction in emissions intensity of 3% per annum for the rest of this century, with emissions intensity of only 8% of current values by 2100. Even that fails to allow for population growth, so the actual reduction required to maintain constant emissions is greater than 3% per annum. That assumes that constant emissions is actually OK. There is considerable reason to think that we must transition to effectively zero emissions by 2050, something that will require around 10% reduction in carbon intensity per annum, or 3% of 2010 carbon intensity per annum. Neither of these scenarios will happen without substantial government policies driving the issue. Even the 3% compounding per annum required just to maintain constant emissions is likely beyond the capacity of private industry unless explicit regulatory frameworks to encourage the reduction are in place.
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  10. Bernard J. @46. I'm sorry, but without the supporting data all you have done is draw a pretty picture that you are asking us to take on faith. I have a math degree, so I don't think I will swoon if post [sic] the supporting data.
    A degree in mathematics?! As others have noted, your naïve treatment of the CO2 data is very much at odds with that claim. However, if it is true, you shouldn't need to see my supporting data. You should be able to see that I performed an analysis that fits the entire Mauna Loa record, and with a bit of application of that claimed degree in mathematics, very soon have a close replication of the graph. I'm extremely curious to see if you are able to replicate the graph, because Tim Curtin with his self-styled skill in statistics never managed what is in the end really a simple procedure. If this turns out to be beyond the skills of someone with a mathematical degree, I might provide a step-by-step description of the process in a few more days, but I really would like to see that you've attempted to arrive at a fit rather more sophisticated than a linear or an exponential fit - for goodness' sake, your own graph and Tamino's explanation should tell you that an exponential fit is rather off base, even with a regression coefficient of 0.98.
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  11. Joel: If you want to project a realistic temperature rise from CO2 emissions including warming in the pipeline from CO2 we have already emitted, there is a simple method of doing do. I did it <20 lines of R code. The method is spelled out in detail in this paper: Rypdal 2012 (open access). For a realistic future projection, you'll need to take into account that we probably can't maintain an increasing output of cooling aerosols, and China are working to reduce their aerosol output because of the health issues.
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  12. skywatcher @57 I read Tamino's post again. He is actually demonstrating that Monckton's assertion of linear C02 growth is absurd. He wasn't trying to prove that CO2 accumulation is super-exponential. You are using what he posted out of context. I reviewed the IPCC scenarios and 628PPM by 2100 seems to fall between the A1B and B2 scenario, so I don't know why you think it is manifestly wrong.
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  13. Tom Curtis @ 59 I have been told in the past that questioning the economic models that the IPCC uses is off limits. If that is not longer the case, then I would love to discuss it. I find the economic models far more questionable than the science.
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  14. scaddenp @58 Since the lukewarming argument is 2 degrees or less, 2.2 degrees as roughly consistent. I'm certainly not going to argue about 10%.
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  15. Bernard J. @60 All you seem to have done is graph the IPCC A1F1 scenario. I don't know you seem to think that corresponds to any definition to the word proof.
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  16. Kevin C @ 61 As far as forecasting the temperature in 2100, then it seems to me that a pipeline cuts both ways. If there is 10 years of heat in the pipeline, then that means that we can ignore what we emit after 2090. I would like to discuss the Chinese situation. They are forecasting that their greenhouse gas emissions will peak around 2050 and start decreasing because of their switch to nuclear power.
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  17. Joel Upchurch @66, why can we ignore it? Does the world end in 2100? Or is this just purely an intellectual exercise for you? More importantly, as is evident from your comment @28, you have been calculating the expected temperature increase from (approx) 2010 levels. In doing so you want to ignore the heat currently in the pipeline, and that in the pipeline at 2100, which is double dipping.
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  18. Joel Upchurch @63, I doubt very much that you have been told that discussing the IPCC's economic projections is of limits. You may have been told they are of topic on a particular thread - but that is not the same as saying they are of limits per se. In any event, I am not asking you to discuss the IPCC's economic projections. I am asking you to identify what you believe will happen so that you can be confident that CO2 emissions will not compound at greater than 3% annually over the next 90 odd years: a) Will economic growth be significantly less than 3%, and why? b) Or will the human population essentially plateau at current levels, and why? c) Or will carbon intensity decrease by 3% per annum compounding over the next 90 years without government regulation or a price on carbon? And if so, why?
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  19. Joel Upchurch @ 62: You claim of Tamino in one of his posts linked to upthread:
    He is actually demonstrating that Monckton's assertion of linear C02 growth is absurd. He wasn't trying to prove that CO2 accumulation is super-exponential. You are using what he posted out of context.
    However, over the course of his debunk of Monckton, Tamino concludes the post with the graph shared here before and some additional comments: log(CO2)
    It sure looks like log(CO2) has increased faster than linear, i.e., that CO2 concentration has increased faster than exponential. We can test this by fitting a quadratic curve to the residuals from our linear fit:
    residual fit
    Sho’nuff. CO2 has increased faster than exponential. Even using the shorter NOAA global dataset. And yes, the result is statisically significant. [Emphasis mine.]
    Suffice it to say that, while demonstrating CO2 concentration is increasing faster than exponentially was not the express purpose of Tamino's post, in direct contradiction to your assertion, he nevertheless does so. Colour me unimpressed, Joel.
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  20. Tom Curtis posted this at 9:50 am and it was unfortunatley accidentally deleted. I reproduce the text here:
    Joel Upchurch, I just did a few calculations based on your comment @28. Based on your projected temperature increases, I calculated that your estimate for CO2 concentration in 2100 is 490-620 ppmv. That later requires an average 2.56 ppmv CO2 groath over the remaining years of the 21st century, ie, a marginal increase over current levels. The former requires annual CO2 growth approx half that of current values for the rest of the 21st century. The median value requires no growth in emissions over current values for the remainder of the century. Your assumptions are simply absurd as a BAU model. More troubling, if you calculate the increase in temperature from the pre-industrial average using your your concentration estimates, we find an increase of 2.4 C over the preindustrial average for the lower estimate, and 3.4 C for the upper estimate. That represents a 1.7 to 2.7 C increase over current values. You only obtained lower values by ignoring the warming currently in the pipeline. (Note: The difference between my estimate and scaddenp's estimate at 58 is that I used a climate sensitivity of 3, while he used 2.8) Most importantly, the median value of 2.9 C is well above the 2 degree above pre-industrial average guardrail for "safe" global warming. Even your dubious luke warm values are way to hot.
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  21. Composer99, nicely put. Saves me one debunking task. Joel, in #23, you asserted it was not plausible for emissions to increase at a sufficient rate to support large temperature rises. You ignored (and continue to ignore) such crucial issues as time delay to equilibrium, feedbacks, and economic/population issues that will lead to continued acceleration of both CO2 emissions and resultant warming at BAU. But in #28 you supported your assertion in #23 with the following statement:
    There is nothing in the actual C02 data that supports an increase to 792PPM of CO2 by 2100.
    Quite apart from the other evidence presented showing that this is patently absurd, I presented evidence that the IPCC have emissions scenarios that consider this entirely plausible, with A1FI and A2 passing 800ppm by 2100. In #62, you try and divert from accepting that you were wrong in your earlier statements by suggesting that the IPCC think 628ppm is plausible [of course they do]. Which was not the question. Let's not chase blimps here. Do you accept that the evidence presented shows that it is plausible for emissions to pass 800ppm by 2100? Or do you want to continue using your extensive mathematical skills to put naive linear trends through 30 years of data, and continue to ignore all other physical factors?
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  22. Joel Upchurch at #65:
    Bernard J. @60 All you seem to have done is graph the IPCC A1F1 scenario. I don't know you seem to think that corresponds to any definition to the word proof.
    Really - "seem to have done"?! If you have a mathematical background you should be able to muck around and actually deduce how I arrived at the trajectory, or at least come to a pretty close approximation. I even gave you some clues. And note, I haven't at any time used the term "proof". What I did say is that:
    ...I constructed the curve...
    and that:
    ...I used the entire Mauna Loa dataset available at the time, and I used the data itself to determine the best projection, rather than directly assuming a linear, exponential, or other fit. I did this by using a process similar to that illustrated by Dana on this very thread, and by using the most parsimonious approach in that analysis to subsequently arrive at the 21st century extrapolation.
    To simplify, as it seems to escape your mathematically-trained attention, I used the entire Mauna Loa dataset, and the trend inherent in the data themselves, to arrive at the graph I displayed. And if that closely resembles the IPCC's A1F1 scenario, well, that probably reflects the underlying supposition of my analysis of a business-as-usual trend based solely on the pattern inherent in the Mauna Loa data. Call me cynical, but given your responses to me and to others here I can't help but question your argumentum ad auditorem claim to have a degree in mathematics. Are you sure that you didn't just take it as a first year subject (if that), and that you're inflating your experience in an attempt to redirect the thread?
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    Moderator Response: [d_b] Easy there, please; no sense in being lured away from the subject at hand by irrelevancies.
  23. Joel, 628ppm would be more like B1 scenario depending on what else was going on. IPCC prediction would be 1.1 -2.9 so I suppose they are luke-warmers too. I normally think of luke-warmers as those how somehow believe that climate sensitivity is less than 2.
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  24. Joel@66: I think that shows that intuition is untrustworthy on this subject. Read Hansens' 2011 paper here, esp. figure 4a. Rypdal's method will allow you to deduce this figure for yourself. The temperature response to a given forcing history is the convolution of the derivative of this function with the forcing. You can see that about 40% of the response comes from forcing in the most recent 10 years, and 60% for earlier forcing. However, if the forcing is much more complicated than an impulse or a step, doing this calculation in your head is impractical. You actually have to do it before drawing conclusions on the results.
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  25. Tom Curtis @67. We are not ignoring the pipeline, but it is irrelevant to the question of how much warming we could expect between now and 2100. If we ask a weatherman how hot we expect it to be Wednesday, we don't have to expect the world to end Thursday to expect an answer. (-Snip-)
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    Moderator Response:

    [DB] "We are not ignoring the pipeline, but it is irrelevant to the question of how much warming we could expect between now and 2100"

    Completely incorrect, as has been pointed out to you. You are pointedly avoiding dealing with this; this reflects poorly on you.

    Goalpost shift snipped.

  26. Tom Curtis @68 Those are very good questions. I can't give you a complete answer tonight, but let me start with B. I first realized that the earth population was peaking when I read "Whole Earth Discipline: An Ecopragmatist Manifesto" by Stewart Brand. It was a shock when I realized that Mexico is at ZPG. Only South America and Africa are still experiencing population growth. The demographic projections are that the world population will peak somewhere between 9 and 10 billion around 2050. (-Snip-)
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    Moderator Response:

    [DB] You were asked:

    "b) Or will the human population essentially plateau at current levels, and why?"

    The first portion of your response was on-topic to that question and translates to: No.

    Further off-topic digression snipped.

    Note: In order for SkS to provide you with the information you have requested, you will have to update your profile with a valid email address (part of the Comments Policy requirements).

  27. Joel, it would help if you made it clear whether you think the calculations in the SRES scenarios are at fault(which would imply you think a linear extrapolation of current trends is better than SRES methodology) or whether you think the economic and population growth projections of the A scenarios are unlikely. I would note that current CO2ppm is already ahead of A1F1 projection. Which SRES storyline for growth etc is more likely?
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  28. Joel Upchurch @76, I note that a population growth to 9 or 10 billion is a growth by 30 to 40%. As DB notes inline, essentially that means your answer to my question is, that, no, population will not plateau at current levels; and indeed, your estimate is essentially the same as my earlier estimate. Your specific comments about current population growth are, as it happens, incorrect based on the CIA World Fact Book (as reproduced by Wikipedia). They are also, however, of topic, so I will not pursue them.
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  29. Monbiot wrote on Ridley's philosophy this summer. His time as chairman of Northern Rock coincided with that bank's disastrous failure. Faulty investments required a huge taxpayer bailout by Bank of England in 2007 and led to his resignation. Of course, this hasn't lessened his contempt for the protective role of governments in economics. Consequently, Ridley is an unlikely source of expertise about long-term risks. "Matt Ridley’s irrational theories remain unchanged by his own disastrous experiment." Guardian
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  30. Jay@79 I did a SkS blogpost on that aspect of Ridley's past, about a year ago. As Monbiot has noted, Ridley has a brass neck to lecture anybody about how risks are overplayed and how government intervention is invariably counter-productive, given his history of presiding over a banking disaster and then begging for a government bailout.Ridley claimed to the subsequent Parliamentary enquiry: We were hit by an unexpected and unpredictable concatenation of events. As Samuel Johnson said (about people who get married for a second time), Ridley's persistent "rational optimism" is a triumph of hope over experience. There's some irony in the fact that Joel Upchurch seems to be supporting Ridley's rosy climate forecast by implying that economic growth will not be anything but exponential, an argument that would be anathema to an economic growth bull and resource cornucopian like Ridley. One last thing, the idea that the temperature increase will be a logarithmic response to cumulative emissions is not correct. Because of diminishing carbon sinks, the temperature response to cumulative CO2 emissions will likely be near-linear as atmospheric concentrations rise. This is explained well at Kate's Climatesight blog. The relevant paper can be downloaded here. Yet one more last thing: projections of greenhouse gas concentrations generally do not incorporate carbon cycle feedbacks. Schuur and Abbott for example, recently did a survey of experts in the permafrost field who forecast that by 2100, there would be an additional 232-380 billion tonnes of CO2 equivalent released from the degradation of organic material in thawing permafrost. That amounts to roughly an additional decade of emissions at current levels by 2100, an amplification to greenhouse gas concentrations that we absolutely don't need.
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    Moderator Response: [DB] Andy, your link is broken; was it this one? http://climatesight.org/2012/05/16/cumulative-emissions-and-climate-models/ [Andy S] Yes, thanks. I have fixed it now. Apologies.
  31. Andy @80, You pointed to an interesting paper about carbon–climate response (CCR) linearity (however your link to "Kate's blog" discussing this paper is broken). I guess in their simulations, they take into account only negative CC feadbacks like seawater invasion/CaCO3 neutralization, although I cannot find any confirmation in the text. Igneous rock weathering does not kick-off in their timescale of 1ka. To me, their CCR linearity applies to the situations of moderate emissions only. Claimed 1.2-1.4 exagram C pulse per dreaded delta T=2K is a very generous allowance. A large pulse like that is likely to trigger positive CC feedbacks including CO2 degassing, CH4 release from permafrost, not to mention albedo change in the Arctic already happening. If they did not consider those, their CCR is underestimated at upper ranges of considered emissions. Finally, it's worth saying that your quote from Schuur and Abbott about possible CH4 release of "232-380 billion tonnes of CO2 equivalent" appears to be incorrect. SA are taking about "tonnes of carbon" here (or at least that's how I read it). BTW, "CO2 equivalent" is a very ambiguous term for me: is it about radiative forcing of CH4 vs. CO2 convoluted with atmosferic lifetime of CH4? Or something more sophisticated that I don't understand? Anyway, in straight GtC, CH4 release in this century by SA is equivalent to 3-4 decades of emissions at current rate. But that's a speculative number, anyway.
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  32. Chris@81 I agree that the Schuur and Abbott figures can be confusing (I got them wrong myself previously.) In one sentence they talk about "tonnes of carbon" and in the next explain that by "carbon" they mean "CO2 equivalents". What they wrote was:
    The estimated carbon release from this degradation is 30 billion to 63 billion tonnes of carbon by 2040, reaching 232 billion to 380 billion tonnes by 2100 and 549 billion to 865 billion tonnes by 2300. These values, expressed in CO2 equivalents,combine the effect of carbon released as both CO2 and as CH4.
    My reading of the Matthews et al paper is that the linearity applies up to cumulative emissions of 2 Trillion tonnes of carbon. They wrote:
    Even in the extreme case of instantaneous pulse emissions, the temperature change per unit carbon emitted in the UVic ESCM is found to be constant to within 10% on timescales of between 20 and 1,000 years, and for cumulative emissions of up to 2 Tt C (see Supplementary Fig. 1).
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  33. Good piece, but "ecosystes", and "supposdely" twice? Time to break out the spell checker. ;-)
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