>>>This reminds me that I was very struck by your survey results regarding this question. For 1996, if I remember accurately, 50% of those surveyed cited ‘population pressure’ as the most serious problem facing the world – to be honest I found this result staggering. The 2003 result was far lower but still large and the largest result – 22% I think? Any views on 1) why the result changed so much? (could it be partly the different cohorts – I seem to remember there were far more Germans in the 1996 survey?) … ?

Why the result changed so much (and these are possible reasons, not empirically backed statements, in other words, at this point, pure speculation)?

In 1996 population growth was a ‘popular’ item. Increased population meant increased consumption, meant increased CO2, and got a lot of media attention. Oddly enough the economic fear of declining western populations (those who consume the most) was not given much thought. Today, population growth has come to mean population growth in rising economic powers and population decline (in the European media at least) has been seen as a problem for western economies.

The 2003 survey was taken post 9/11/2001. In 1996 only 4 respondents wrote ‘war’ as a response and only 2 respondents wrote ‘terrorism’. In 2003, 28 provided the response of terrorism and 21 ‘war’. In the 2003 survey ‘global inequality’ was the response of 29 respondents (maybe to do with the publicity of things like Darfur) while in 1996 only 8 respondents reported ‘global inequality’ This suggests the influence of competing issues.

The German participation – in 2003 we sent the survey to web-lists such as CLIMLIST, so that we addressed an international group; in contrast, in 1996, we sent the survey to members of the German Meteorological Society and members of the Max-Planck Institute in Hamburg, which resulted in many more returns form German scientists.

>>>>and 2) Why climate scientists are so pessimistic about population growth?
– we do not know, but they may have the same concerns as all other people.

>>>>On another note, in the survey paper I was struck by the juxtaposition of Figs 35 & 45. They seem to suggest that scientists have become less confident that they understand climate impacts on human systems, but also less concerned that those impacts will require much change.”

Figure 35, on the question “To what degree do you think it would be possible for most societies to adapt to change without having to make any substantial changes to current societal practices?” did contain a coding error and has since been corrected. It was a case of the labels being reversed in the 2003 survey, as compared to the 1996 survey. The corrected frequencies are presented below. There was indeed some change in the perceived need for substantial changes to current societal practices – categories 1-3, pointing to such a need, went down from almost 72% in 1996 to about 57% in 2003, while categories 5-7, showing doubt in such a need, went up from 15% in 1996 to about 26% in 2003.

Revised %-frequencies for Figure 35: “To what degree do you think it would be possible for most societies to adapt to change without having to make any substantial changes to current societal practices?”

___________________1996 2003
there is a need_______12.0 9.5
for many changes
2 _________________29.9 25.9
3 _________________29.9 21.2
4 _________________11.9 12.6
5 _________________9.9 14.0
6 _________________4.2 8.4
no substantial________1.3 3.4
change necessary

Figure 45 accurately reflects the data. Again, one can only speculate as to the reason for change. It might simply be the case of a greater involvement of social scientists in the climate change issue bringing to light the complexity of the relationship between things social and things natural, that had previously remained unquestioned.

Dennis Bray and Hans von Storch

1. What do you think is the likely range of equilibrium climate sensitivity for 2xCO2 equivalent in degrees C? (IPCC definition of likely)

2. What do you think is the temperature increase at which mitigation costs equal benefits of mitigation (assume the year is 2100 if that affects your answer)?

Answers to these two questions could be used to place the respondent on a 2D map with believed severity of climate effects as one axis and of economic effects as the other.

Performance Artists

Scientific or engineering knowledge secondary to communications skills ; may have undergone professional training as actors as media presenters. examples are TV weathermen and some NOVA and NGSTV hosts.

Dezinformatsniki

Cold War veterans from both sides translating skills gained in lying for their countries into the service of private sector clients. E.G.: former Nuclear Winter advocates who have graduated from advocacy on behalf of the Politburo to the advertising apparatus of energy companies in the CIS.

Televangelists and Author/Producers

Primary training in homiletics , apologetics and politics ; relative amatuers appear widely at revival meetings , more politically accomplished examples servicable as Hollywood , or at least Indy talent . Type specimens Al Gore, Bill Moyers and Martin Durkin.

Professional Dystopians

Carrying the Precautionary Principle to its exponential limits , they promote worst-case modeling as prudential, and endeavor to see to it that outlier scenarios are well represented in the peer-reviewed literature. Examples: Paul Ehrlich and Donald Kennedy.

Pure Opportunists

Focused on commoditizing policy debates regardless of their scientific outcome or resolution. Examples : Carbon derivative traders , wind farm tax shelters, and high latitude and present marine CO2 offset schemes. Many operators have boiler shop experience , and some have been subject to SEC and IRS code sanctions.

Set aside the action dimension for the moment (which I think is orthogonal, having more to do with perceptions of the appropriate role of science). Arrange the other two (denial/belief and hi/lo consequence) in quadrants. If you’re in the upper-right quadrant (belief in AGW, high consequence) then you’d tend to be Pro (concerned or advocate). Anywhere else, you’d tend to be Con, because the impetus for policy is essentially multiplicative (i.e. needs both significant climate sensitivity and significant impacts). You could label the other quadrants (e.g., belief in AGW but lo consequence = greening earth?) but I think it’s reasonable to use this as a way of reducing the number of categories.

I had a little trouble placing doubters because in my mind, doubt does not translate to inaction, unless perhaps your priors are symmetric and zero mean (i.e. cooling and warming, good and bad impacts equally likely). Armstrong & Green appear to hold that view, but I suspect it’s not common.

I think what is missing is one more dimension: cost of mitigation (hi/lo). That’s a question that’s traditionally in the realm of economics, but I suspect that most scientists have an opinion about it (much as they do about economic impacts, where they may also have little formal expertise). Presumably views on mitigation cost color judgements about what to do when in doubt and whether to be a puzzle solver or activist.

I’d hate to add mitigation as a 4th dimension. A solution might be to collapse the interpretation and consequence dimensions into one (I’ll call it significance for want of a better word, with values low – no AGW or no impacts or both, and high – AGW exists and matters). Then (still ignoring action) you have quadrants defined by mitigation cost (low/high) and significance (also low/high) – essentially two sides of the cost benefit equation. High significance, low cost favors a pro stance. Low significance, high cost favors a con stance. Low significance (or doubt as to significance) and low cost favors a “no regrets” stance. High significance, high cost might favor a “wait for technology” approach.

With this revised approach to the dimensions, I think you’d still end up with a similar set of categories, but you might have a clearer separation of certain motivations – particularly whether positions of “doubter”, “advocate” or “concerned” arise from a sense of one’s role as a scientist or from mitigation cost considerations.

On another note, in the survey paper I was struck by the juxtaposition of Figs 35 & 45. They seem to suggest that scientists have become less confident that they understand climate impacts on human systems, but also less concerned that those impacts will require much change.