Posts Tagged ‘Hans von Storch’

A critical look at “The uncertainty has settled” documentary by Marijn Poels

July 17, 2017

(Zie de Nederlandse versie door Jos Hagelaars op ons Klimaatverandering blog)

The documentary “The uncertainty has settled” from Dutch filmmaker Marijn Poels follows him on his journey in rural Austria and Germany to witness how energy policies impact traditional agriculture. That is the stepping stone to also look into different ideas about how and why the climate is changing. Unfortunately Poels has no clue how to distinguish fact from fiction, and by his own admission he has no interest in making that distinction. As a result the documentary offers a mix of basic scientific insights, plain falsehoods, and misleading statements regarding climate science. As an unwitting viewer you are left utterly confused –cued by Poels’ facial expression at those times- how to reconcile these seemingly opposing viewpoints. Creating confusion was apparently his objective (as he acknowledges on his website), but it makes for a surreal experience if you know you’re being fooled. I think spreading falsehoods is doing a disservice to the public, as I’ve said to Marijn Poels during a radio-debate (in Dutch).

Let’s look more closely at some of the things being said about climate change in the documentary.

Marijn Poels meets another Dutchman in rural Germany, who laments how climate policies have led to the disappearance of local nature. He says it’s insane to think that a CO2 concentration as low as 0.035% (currently 0.04%) could have any impact on climate. That’s clearly fallacious reasoning (argument from incredulity): there are plenty of examples of compounds that have serious impacts at the same or lower concentrations (e.g. a CO detector will sound the alarm at such a concentration and you had better leave the premises). Without any CO2 in the air the globe would quickly become a frozen ball of ice, since the main air constituents (nitrogen 78%, oxygen 21%, argon 1%) don’t impede the infrared heat loss to space.

Later in the documentary he meets with climate scientist Hans von Storch, astrophysicist Piers Corbyn and physicist Freeman Dyson. Those in the loop will immediately recognize that this is not at all a fair representation of the scientific debate, but rather provides a very skewed vision thereof by emphasizing outlier views that are demonstrably false.

Hans von Storch accurately describes our current knowledge about climate change: We know that the earth has warmed and we can’t explain this warming without considering the human-induced increase in greenhouse gases in the atmosphere. He also distinguishes how scientific knowledge may be very uncertain in specific details, while the core tenets are robustly known: “The fact that CO2 has a significant influence on climate is indisputable.”

It’s astonishing how many falsehoods and conspiracy theories Piers Corbyn mentions over the course of few minutes.  Some of the things he said:

FALSE: The increasing CO2 concentration in the atmosphere is coming from the oceans

If Corbyn were right, the concentration in the ocean should have decreased in order to explain the increased atmospheric concentration (a simple consequence of conservation of mass). However, CO2 concentrations have been observed to increase both in the atmosphere and in the ocean. In reality, the excess CO2 in both atmosphere and ocean originates from fossil fuel burning, as is evident from the isotopic signature and the concomitant decrease in atmospheric O2 concentration.

FALSE: CO2 only follows temperature

During the ice age cycles CO2 acted as an amplifying feedback on the warming which was initiated by changes to the earth’s orbit. During those times of relatively slow warming the temperature indeed started to increase before the CO2 concentrations did, after which the CO2 caused even more warming. Hence it’s a bit of a chicken-egg issue with CO2 and temperature, but Corbyn’s statement is misleading. The current CO2 increase is unequivocally anthropogenic and ~100 times faster than it was in glacial to interglacial transitions. Moreover, we have known since the mid-nineteenth century that CO2 absorbs infrared radiation and thus acts as a greenhouse gas which impedes planetary heat loss and thus warms up the surface.

FALSE: Termites produce more CO2 than human activity does

Termites produce less CO2 than human activity does. Moreover, while anthropogenic emissions have led to the increased CO2 concentration, there’s no sign of tremendous changes in termite populations or emissions. In general, CO2 uptake and release by the biosphere (through assimilation and respiration/decomposition, respectively) approximately balance over multi-annual timescales. Termites also emit methane, another greenhouse gas, though around 40 times less than is released through human activity.  [Text about termite emissions has been updated 17-07]

FALSE: A new mini-ice age cometh

Corbyn has been predicting this for a while now (at least since 2010), but reality so far has been going in the opposite direction compared to his predictions. Scientists have investigated the potential consequences of a quieter sun in the near future, but generally find that increased greenhouse gas concentrations will dwarf any realistic decrease in solar activity, and hence the globe will continue to warm for the foreseeable future.

CONSPIRACY THEORY: The increased temperatures are a result of fraud with the observations

Globally averaged temperatures are computed independently by a number of different research group and they all agree within a close margin of each other. The raw data are available, so everyone who’s interested and who has the requisite skill can try to reproduce (or falsify) these calculations. A number of ‘skeptical’ people have indeed done so, and lo and behold, they found the same result: the globe really is warming.

Corbyn continues with his conspiracy theories and doesn’t even seem bothered that they’re mutually inconsistent with each other: on the one hand he claims that the ‘climate ideology’ has been made up by international big business interests, on the other hand he also claims that the ‘myth of climate change’ is a scheme to de-industrialize the West. How can you possibly take someone like this seriously?

Next up is renowned physicist Freeman Dyson, who is very skeptical of the ability of climate models to make accurate projections of future warming. In the documentary he paints a false dichotomy between observations on the one hand and models on the other hand, whereas in modern science they really go hand in hand and models form an integral part of science. Model simulations agree very well with observations, despite Dyson’s claims to the contrary. For good measure he also throws in a conspiracy theory by claiming that climate modelers only want to scare people, because they wouldn’t get money for their research otherwise. This goes to show that otherwise brilliant people can still make silly claims about a field of science that they don’t know much about.

So why did Marijn Poels chose to interview people who are demonstratively wrong (and who are not actually climate scientists)? His whole idea with the documentary was as a personal quest in which he listened to various viewpoints without judgment or evaluation. In a radio-debate I did with him on Dutch Radio NPO1 he proclaimed that he doesn’t feel any responsibility to figure out who’s talking sense and who’s talking nonsense. On twitter he has since confirmed that he doesn’t care what true and what’s not. I find that a very strange attitude for a documentary-maker, as I tried saying at the end of the radio-debate:

Scientists are seeking a better understanding of the world around us. What I hear Marijn Poels say is that it doesn’t matter to him what’s true and what’s not. That goes against everything I value as a scientist.

He also tweeted that “if there are multiple scientific perspectives, then it’s worthy of debate”. So the problem is not only that he doesn’t care about whether something is true or not; he doesn’t see that some of what he calls “scientific perspectives” are plain untruths. Claiming that the CO2 might just have come out of the ocean is no more a ‘scientific perspective’ than claiming that vaccines cause autism or that smoking is not linked to cancer. Science has conclusively shown these statements to be false.

In a public debate about smoking regulation there’s no point in discussing whether smoking is really bad for you: we know that by now, based on scientific evidence.

Likewise, in a public debate about climate policies  there’s no point in discussing whether CO2 really contributes substantially to climate change: we know that by now, based on scientific evidence.

New survey of climate scientists by Bray and von Storch confirms broad consensus on human causation

June 22, 2016

Bray and von Storch just published the results of their latest survey of climate scientists. It contains lots of interesting and very detailed information, though some questions are a little biased in my opinion. Still, they find a strong consensus on human causation of climate change: 87.4% of respondents are to some extent convinced that most of recent or near future climate change is, or will be, the result of anthropogenic causes (question v007). Responses were given on a scale from 1 (not at all) to 7 (very much). In line with Bray (2010) a response between 5 and 7 is considered agreement with anthropogenic causation. In their 2008 survey the level of agreement based on the same question was 83.5% and in 2013 it was 80.9%.

How convinced are you that most of recent or near future climate change is, or will be, the result of anthropogenic causes? (v007)
not at all   1     2     3     4     5     6     7   very much
Bray and von Storch 2015 - v007 how convinced are you that most of recent and future GW is or will be the result of anthropogenic activity

Question v013 asked a somewhat similar question as we did in our 2012 climate survey, namely the percentage of global warming that is attributable to human activities:

Since 1850, it is estimated that the world has warmed by 0.5 – 0.7 degrees C. Approximately what percent would you attribute to human causes? (v013)

1=0%   2=1-25%   3=25-50%   4=51-75%   5=76-100%
Bray and von Storch 2015 - v013 What percentage of global warming since 1850 do you attribute to human causes

84.2% of respondents picked one of the two answer options that correspond to the canonical “more than half” or “most” of global warming that according to the IPCC is human caused. However, the corresponding IPCC statement is with regards to warming since the 1950’s, about which there is a lot more confidence, whereas this question specifies the warming since 1850.

But wait a moment, hasn’t the earth warmed a lot more than 0.5-0.7 degrees C since 1850? Yes, it definitely has; we’ve recently breached the 1 degree mark relative to the 1850-1880 average, so the range given in their question is quite outdated. A defensible choice at the time of drafting the survey would have been to quote the latest IPCC number of 0.85 (0.65 to 1.06) degrees warming over the time period 1880-2012, even if current temperatures have gone up sharply since then.


Global average surface temperature relative to the 1850-1880 mean. Last annual average shown is 2015; if the first few months of 2016 are a guide, the vertical scale might have to be adapted for 2016. Figure by Jos Hagelaars.

Moreover, the answer options for v013 do not cover the full range of possibilities. Natural factors could have caused warming or cooling. Imagine that natural factors would have caused a cooling of 0.1 degrees C since pre-industrial times (which is not at all implausible), then to achieve closure with the observed warming of 1.0 degrees, anthropogenic factors should have contributed 1.1 degrees, or 110% of the observed warming. We discussed this argument in detail in our ES&T paper emanating from the climate science survey we conducted in 2012.

I emailed Dennis Bray about these and other issues after having responded to their survey back in 2015. He defended their choice of lowballing the observed warming as being consistent with their previous surveys and not being much different from more recent, and also likely contested, estimates. Strangely, he disagreed with the possibility of a factor being responsible for more than 100% of the observed warming, even in the hypothetical example above.

Cook et al (myself included) recently wrote an article in which we reviewed the existing ‘consensus’ estimates. This latest Bray and von Storch survey finds a level consensus on attribution that is consistent with other studies, though towards the lower end of the range. From their description I don’t think there is a bias in their sample of scientists, though there is always the possibility of self-selection, where people might be more likely to respond to a survey if it originates from a source who they perceive to be credible. Repeatedly, surveys have found that the level of consensus goes up as you zoom in to a sample of scientists with more relevant expertise. The Bray and von Storch results, as are ours, are mostly representative of a broad group of climate related scientists.

A detail of particular interest to me is that the survey questions included the response option “no answer”. That explains the different sample size for different questions (“Number of obs”). It’s probably no coincidence that question v013 (asking for a specific range of percent contribution) has a smaller sample size (n=587), and by inference more “no answer” responses, than the other, but simpler, attribution question v007 (n=640). This is consistent with what we found in our 2012 climate science survey: fewer respondents picked a specific percentage range of attribution compared to providing a qualitative judgment thereof. Though admittedly “no answer” (in the Bray and von Storch survey) is less ambiguous in this context than “I don’t know”, “unknown” or “other” (in our survey).

Amidst the questions on science and society I perceived some questions to have an “anti-consensus” (v069) or “anti-alarmist” (v067) tone to it, but there were no questions asking for mirror image perceptions. Doomsday stories need to be investigated before they get out of hand (v067): of course. But no question was asked whether stories downplaying a scientifically established risk should be investigated. I would have likewise responded: of course. To his credit, Dennis Bray acknowledged in his email that this was an oversight on their part.

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