Hansen claims that there are pressures on scientists to understate rather than overstate risks. I am not sure this phenomenon applies to all scientists everywhere, but it certainly applies to climate scientists in the US, where the perception of the consensus position is that it stands at one pole of a scientific debate, rather than constituting a center of gravity around which excursions in both directions are healthy and worthy of investigation.
However, it is not fair to simply shrug this off and say it cuts only one way in general. The constellation of forces arrayed around climate science (geology, agriculture, military, civil engineering) are naturally conservative. Other groups may feel very different pressures.
For instance, reticence does not seem to apply to environmental nonprofits.
I am particularly unhappy to face up to the fact the propagandistic skewing of data recently demonstrated by the Audubon society. Toxic environmentalism is real enough, and it's really shocking to see it an an association as venerable as the Audubon Society. It's hardly surprising that a survey of species shows the ones in most rapid decline as declining rapidly. This must be placed in context of the rest of the survey, which the Audubon Society, almost surely deliberately, did not do. In fact, if I understand correctly, and more appear to be increasing rapidly than decreasing rapidly in their survey, but Audubon appears to be taking considerable care to leave a different impression.
Reason requires fair attention to evidence. It is necessary to resist pressures to skew what your data means, regardless of who butters your bread. These days that is all too commonly difficult, and to that extent, regardless of his severely confused ideas about climate, Lubos Motl has a point.
Here's a quote from Paul Dietz, duly crediting John McCarthy, which I found on an interesting discussion about AGW skepticism :
Agreed. Of course McCarthy usually talks about lawyers' science on the part of environmentalist groups. Let's try to remember that the pressures run in both directions, and let's try to have the courage to tell the truth regardless.
Yes, this is a great symptom of denialism, showing what John McCarthy called 'lawyers's science'. You start with the position you want to prove, and search for evidence, however thin or dubious, to support it. The result is the jumping from one easily debunked argument to another.The surprising thing is the persons exhibiting this behavior often don't allow themselves to realize what they are doing.