So if the book had been titled, “Dire Projections: Understanding Global Warming,” their “message” would be “lost”? In what sense would their “message be lost”?

P.S. Regarding the post on your blog: If Al Gore “…clearly has a good understanding of climate science,” then he doesn’t care much about accuracy. His advice to his audience to look at the pre-industrial history of CO2 concentrations and temperatures, and then imagine what temperatures would result from current and projected future CO2 concentrations, was bunk. (As was his simulation of sea level changes that would occur over as much as centuries as though they would occur instantaneously in the near future.)

I wrote about this catch 22 situation here: http://ourchangingclimate.wordpress.com/2009/03/12/catch-22/

Mann explains his choice of the word ‘prediction’ clearly having a lay audience in mind, and argues that using the term ‘predictions’ better conveys the key message to the intended audience than using the technically correct term ‘projections’. Perhaps it’s best to judge it by its key message, and assess whether that’s been bent out of shape in the process.

A scientist using strict scientific language in engaging with the public may as well stick to scientific conferences instead, since it won’t lead to any increased understanding on the part of the public. Yet, a balance still has to be maintained, as e.g. Gavin points out in the same article: Framing should be used to better convey the key message, not to sell a particular product or viewpoint.

Did you see any estimates of the probability of occurrence for any of these scenarios? (Hint: No, you did not.)

The IPCC has *never* answered this singularly important question. Look at any of the four IPCC Assessment Reports released to date (including the fourth Assessment Report, AR4, released in 2007). ”

This is simply not true. I just spent 10 minutes searching IPCC reports and found scenarios that attempt to predict a business-as-usual scenario, and that include error bars.

No, the difference between “predictions” and “projections” is that “predictions” can be falsified, and are therefore legitimate science, whereas “projections” (of the type made by the IPCC) cannot be falsified, and are therefore not legitimate science.

That’s a mountain of difference, not a molehill.

The most important question by far regarding climate change is, “What will climate change be like if there is no intervention by governments?” In other words, “How much will the world warm if governments do not intervene to reduce warming?”

The IPCC has *never* answered this singularly important question. Look at any of the four IPCC Assessment Reports released to date (including the fourth Assessment Report, AR4, released in 2007). In NONE of them is there an estimate of the most probable warming (i.e. the 50 percent probability warming) in the 21st century. Likewise, there are no upper and lower probability estimates (e.g., the level of warming below which there is only a 5 percent probability of occurrence and the level of warming above which there is only a 5 percent probability of occurrence).

This lack of a probabilistic estimate of warming in the 21st century in any of the IPCC’s four Assessment Reports is undoubtedly not due to mere incompetence. It’s unquestionably due to scientific fraud. It is the deliberate passing off of unfalsifiable (i.e., non-scientific) “projections” as legitimate science.

Thanks. I actually agree with your views on prediction/projection. Had Mann made the same case, I’d have no problem with his comments. However, he maintains that the terms are different and one is technically correct whereas the other is not, but he chose the incorrect term (in his view) in order to shape public opinion. The issue here is Mann’s revealed thinking, not a semantic point.

Among those who continue to believe claims of Cold Fusion are not attributable to error, some possible theoretical interpretations of the experimental results have been proposed.[107] As of 2002, according to Gregory Neil Derry, they were all ad hoc explanations that didn’t explain coherently the given result, they were backed by experiments that were of low quality or non reproducible, and more careful experiments to test them had given negative results; these explanations had failed to convince the mainstream scientific community.[107] Since cold fusion is such an extraordinary claim, most scientists would not be convinced unless either high-quality convincing data or a compelling theoretical explanation were to be found.[111]”

In other words – to frame it – the original results were replicated by many groups, and they still are being investigated around the world, but because it doesn’t seem theoretically possible, mainstream science demands the finding of sources of error. This is the well-known group think mentality that if the prevailing theory is well-established then the data must be wrong. An attitude you are usually one the first to complain about. Easy to fall into this trap isn’t it? In fact, as Wikipedia relates quite well, research on cold fusion is still ongoing up to 2009 and is still producing surprising results that aren’t readily explicable.