Wednesday, August 18, 2010

H.J. Schellnhuber Interview in English translation

Today, spiegel online published an English translation of the interview.  Great service! (thanks, Harold, for the link).


Georg Hoffmann said...

Beeing a bit reptitive: There is nothing really shocking in this interview.
One minor point concerning the floodings in Pakistan. There is no agreement whatsover between the different climate models concerning the reaction of the monsoon on raised greenhous gas levels. In other words, th floodings are as much in line with model predictions as a mayor drought would be.

Hans von Storch said...

I would say, this is pretty shocking, and clearly non-Mertonian:

From today's scientific perspective, we could possibly live with a warming of two to three degrees. ... The overwhelming majority of climatologists assume that a global temperature rise of four degrees would be an immensely dangerous route that we should avoid at all
SPIEGEL: Why then have you, as one of the creators of the two-degree target, imposed such a magical limit to which all countries must slavishly adhere?
Schellnhuber: Politicians like to have clear targets, and a simple number is easier to handle than a complex temperature range. Besides, it was important to introduce a quantitative orientation in the first place, which the 1992 Framework Convention on Climate Change managed to elegantly wangle its way out of. And let's be honest: Even if we aim for the two-degree target, we'll end up somewhat higher. Whenever there's a speed limit, most drivers tend to go a little faster.

Scientific assertions taylored according to political utility.

Georg Hoffmann said...


Did you (or someone else) really take the 2°C as a scientifically based absolut and hard limit, ie there is an equation, line of evidence, simulation, whatever and at the end there is the outcome: humanity shall not trespass 2°C, never!

(as you know the way the corresponding emissions are computed this means actually that there is a 50% chance to remain below this target).

This was allways a political target (something like "Die Rente bleibt sicher") and I still think that it is reasonable to help media and politics by such kind of handy formulas.

Jerome said...

There's something I don't undestand. What exactly does Schellnhuber mean when he says "From today's scientific perspective, we could possibly live with a warming of two to three degrees"? Via WBGU, he has told us for a decade, that temperature rise must not exceed two degrees. Has this ONLY been a political statement?

@ReinerGrundmann said...

Schellnhuber has modified his position: previously he said the 2 degree target was dictated by science, now he admits it is a political goal. While this frank admission may be intended to restore credibility it will raise more questions I guess.

isaacschumann said...

If Shellnhuber displays this level of candor in an interview in der spiegel, why does he feel the need to simplify issues for the 'public'? Is the readership of spiegel not the public?

And if the media has done a poor job of relaying the complexities (positive vs. negative effects) and uncertainties in climate science to the public (which I agree they have), than why have not more scientists made light of this when speaking to the public themselves. More often they seem to do the opposite, upbraiding the media for printing views they do not like.

Furthermore, if Shellnhuber and the vast majority of climatologists believes it is uncertain what life will be like for humans in a world 2C hotter, why are they more confident that a 4C warmer world would be 'immensely dangerous'? IMHO, I would think that a world 4C warmer would be immensely uncertain (not that I am advocating finding out) but I'm only a microbiologist, so what would I know anyway:)

isaacschumann said...

i don't mean to be too critical in my last post, I really appreciate Shellnhuber being more candid, and I think other climate scientists are doing the same (Schmidt, Trendbreth come to mind) and I want to support this. It is, however, vexing to compare this more reasonable tone to past statements in the media.

Georg Hoffmann said...




Why speed limits at 100km/h or 130km/h or whatever? If you might survive a crash at 100 you might even survive one at 130? So if the whole business is so uncertain than no limit, not even in cities or in front of the kindergarten. Since it's uncertain.
In other words, it's rather a general impression that 2C might be ok (might be it isnt) and 4C is not (might be it is).

isaacschumann said...

Thanks Georg,

My point was that first we were told 2C of warming means death! and now that we are approaching 2C we are told '2C might be OK... but a 4C rise means death!'. i dont have a problem with general targets like this, just that people would describe them as you do, as general benchmarks.

Hans von Storch said...

Georg, what you do not understand is that it makes a difference if somebody makes a statement with the authority of science - i.e., assertions which are based on a methodology many would associate with a set of rules like Merton's - or an ad-hoc decisions about social acceptability of risks. Thus, the question is not if we like the answer, but how he arrived at the answers. The authority of science is based on the methodology, not on the appeal of the answers.

Hans von Storch said...

Jerry - Via WBGU, he has told us for a decade, that temperature rise must not exceed two degrees. Has this ONLY been a political statement? - in the interviews he gives the answer: YES, this was a political statement. - Hans

Georg Hoffmann said...


When I sea you or Schellnhuber speaking at the TV and you make statements like "Wir werden das schon wuppen" or "4°C warming leads to mayor disintegration of human societies" (in both cases I am not absolutely sure if yours or Schellnhubers citation is more or less correct) then this is allways a political statement: Simply because these are statements a) made in mass media which are not made/designed for any kind of scientific statements and b) of such a general kind that science never could come up with such conclusions.
Point b is understood by any intelligent audience and I repeat my question: When you first heard of a 2°C objective have you thought that Schellnhuber or whoever else made a rock solid or even not so rock solid computation based on scientific methodology to come to this number?

Anonymous said...

"Why speed limits at 100km/h or 130km/h or whatever? If you might survive a crash at 100 you might even survive one at 130? So if the whole business is so uncertain than no limit, not even in cities or in front of the kindergarten."

Oh my goodness.

eduardo said...

The 2C limit or benchmark as been adopted officially by the European Union a a guidance for its climate policy. But most public opinion has probably understood that this limit has set by science. Climate researchers know that it is presently impossible to predict that a particular emissions path would lead to 2 C warming, and it is equally impossible to predict what a 2 C warming actually means for climate impacts.
Let us imagine, the World Health Organization had issued a statement saying that smoking under 10 cigarettes per day would be more or less safe, but beyond that it is dangerous. Years later, the same Organization says that the limit of 10 cigarettes was just decided in the pub after a meeting in Geneve. I could understand that most people would feel cheated.

On another matter, I find it curious that Prof. Schellenhuber is candid enough to propose reserving 10% of the parliament seats to unelected obmudsmen for the next generations. Perhaps we should remind Prof Schellenhuber that there are 7 million foreigners living in Germany, which are not entitled to vote or be candidates, as in many other European countries for that matter. Apparently, unborn citizens may have more rights, provided they vote in the 'correct' direction. It is a quite remarkable understanding of a democratic society

Werner Krauss said...

I agree with Hans that Schellnhuber does not follow the strict rules of natural science. But in this interview, Schellnhuber also does not really pretend doing so. Obviously, he has a different understanding of what climate science is. He does something you might call 'applied science' - he has both climate change and politics in mind. He adjusts science to the needs of politics (or what he thinks the needs of politics are). He is pretty open about that. Thus, he mixes science and fiction (which ends up consequently in science fiction). As far as I know, he already said earlier that 2 degrees is a fake number (or a political number). He also said otherwise (that it is a scientific fact) - this is true, too. He presents himself as a story teller who always has his audience in mind (and adjusts the narrative accordingly). We know this attitude from many other public-oriented sciences (such as economy for example).

As far as I see, there is no consensus that defines what climate science is. Hans obviously has a very strict scientific (what he calls Mertonian) understanding. But as we know, many others interpret climate science differently. Schellnhuber is not the only one who easily mixes science and fiction in this field (remember the recent Latif interview in BILD). There is nothing wrong with that - fiction can be as precise as science (or as bad as science unfortunately can be, too).

The main problem for me is that Schellnhuber presents poor science fiction. The whole global limit and 'end of the world' discussion does not lead to proper results. He also does not talk about adapting to a changing climate. I think this is the main problem with this interview - not the misuse of science or scientific authority (he indeed is pretty open about this, in my reading), but the general approach to climate politics that he suggests. We urgently need other narratives about anthropogenic climate change - such as discussed and suggested for example in the Hartwell paper discussed here on klimazwiebel.

Georg Hoffmann said...


"I could understand that most people would feel cheated."

But they shouldnt. To my knowledge (I might be wrong) there is actually no benchmark in health or environment related laws or rules which is clearly just based on science. Nor the the 10 cigarettes (if that were true), nor the 0.005 Sievert per year radiation nor the quantity of mercury allowed in water nor the speed limit in front of the Kindergarten (etc etc ). These are science-motivated political values. These values represent a compromise of some science (radiation produces cancer, but nobody knows how much radiation exactly), what can be measured (you cant control a benchmark even if it is a "reasonable" one if the benchmark cannt be controled with standard techniques), and what is somehow considered as safe (in a very subjective way, among a group considered as experts for cancer, traffic safety, sitting in a pub or not).
To propose a 2°C as an acceptable benchmark for global warming based on the very same mixture of technological limits (a benchmark of 2.16°C doesnt make sense since you cannt measure it), economical limitations (a benchmark of 0°C might be nice from a climatological point of view but unfortunately means the end of modern economies as we know it) and subjective estimations of what might be safe and what might be risky.
I cannt see any important difference between imposing a 0.005 Sv/year safe radiation limit and a 2°C target for future global warming.

"Perhaps we should remind Prof Schellenhuber that there are 7 million foreigners living in Germany, which are not entitled to vote or be candidates, as in many other European countries for that matter."

A kind of a "non sequitur". The fact that there are other possible problems in the democratic process does not mean that you are not allowed to take care of a problem you are worrying about. In fact finally nobody could worry about anything since there is allways a bigger injustice/problem/desaster.

richardtol said...

On the two degrees target, it is instructive to read the 1995 WBGU report:

They argue as follows. For as long as modern humans have existed, it has never been warmer than 1.5K above pre-industrial. (Paleoclimatology may have moved on since then.) Let's add (note: add, not substract) an arbitrary safety margin of 0.5K. 2.0K results.

True brilliance is trivial in retrospect.

I would argue, though, that this was one of the less brilliant moments of the WBGU.

The two degrees target was adopted in 1996 by the German government and the EU -- at a time when no one was really paying attention -- and it is much easier to keep a target than to change it.

richardtol said...

For health, limits are set as follows: The maximum allowed dose is one-tenth of that dose that kills five percent of rats.

There are three arbitrary choices, but it is an empirical matter after that.

This line of reasoning does not apply to climate change, because it is a two-sided risk: Aggressive emission reduction is very expensive.

For climate, you cannot define a "safe" level; you have to balance risks.

Georg Hoffmann said...

But men are not rats and so that doesnt really help.
"Aggressive emission reduction is very expensive."

The level of security asked in nuclear energy production (power plants, ulitmate disposal, transport, etc.) as well.

"For climate, you cannot define a "safe" level; you have to balance risks."

And so for radioactivity. How many people would die without electricity? Each of these benchmarks are scientific-political compromises. To "discover" that there are other criteria than just pure science involved in it is not really a big surprise.

richardtol said...

You get you numbers all mixed up. Nuclear safety and food safety are very cheap compared to stabilising greenhouse gas concentrations at 450 ppm CO2eq.

Georg Hoffmann said...

Try not to get my simple analog mixed up.
Nuclear energy: expensive
450ppm: expensive

Safety standards: political, technological, subjective

climate benchmarks: political, technological, subjective

I cant see anything or new or undemocratic or unusual in defining and formulating such political objectives.

However and by the way I would see something undemocratic if the decisions on emissions scenarios were EXCLUSIVELY the result of cost/benefit computations.

Hans von Storch said...

Georg, what are the quality standards you would expect from a scientist acting (employing the authority of science) in the public arena. - Hans

richardtol said...

Nuclear safety is cheap. Just switch to coal. If you do it in a rush, the lights will go off.

Zero-carbon energy is expensive. Switch to what? If you do it in a rush, people starve.

I did not say anything about cost-benefit analysis. I wrote about one-sided and two-sided risks.

Georg Hoffmann said...


I guess the quality standards for a scientist in exchange with the public are not fundamentally different from any other profession, in particular politicians. Since in the very moment he/she appears in the public domain he/she changed allready his/her role model. And that implies in particular that he/she should be honest and all that stuff. Sometimes people seem to think just because someone is politician he is allowed to lie.

A scientist is a scientist in the science environment (lecture hall, papers, in the pub with his collegues). In the moment he appears in front of the camera he/she is just another public actor who should try to be honest, has some values, formulates sometimes badly and sometimes better and so on. His particularity is that his subjective judgments are probably more science based whereas the public judgments of a catholic priest might be more bible-based.

I do not expect a completely neutral being lead by a sort of extraterrestrial perfect logic. A russian and a german nuclear physicist might come to quite different conclusions on what nuclear safety standards should be though they share common scientific information. There are allways subjective (culture/gender/age/etc dependent) judgements involved and the idea of a completely neutral scientist might be misleading from the beginning.

If there is something I would complain about in Schellnhubers interview it is that he should stress even more these unavoidable subjective preferences. For example he makes this suggestion with the ombudsmen for future generations (I think it doesnt work, but that's another issue). He should point out that such preoccupation about future generations is HIS very political decision and preference and there might be political movements and ideas that do not or not so much worry about the problems of future generations.

Anonymous said...

@Georg Hoffmann

"there is actually no benchmark in health or environment related laws or rules which is clearly just based on science."

Who makes the benchmarks and who makes the science behind these bench marks?