No Se Nada

# 1 | John Sidles | January 27, 2006 7:22 PM

Maybe Dr. Hansen read Jared Diamond's "Collapse" & decided that the rate biosphere degredation was too grave, and the consequences too irreversibly severe, as to justify his continued reticence.

# 3 | Gordon Mitchell | January 29, 2006 11:42 PM

Closer examination of the 1998 AARST forum transcript available here complicates the Hansen "change of heart" thesis. In a Q&A exchange with an audience member (pp. 167-168), Hansen discusses policy and provides a caveat to frame his comments:

Audience member: "I have a question for Dr. Hansen, and I just thought of a little spin for Dr. Michaels, as well. In the beginning of your presentation, you said that you would attempt to suggest that there was sufficient scientific evidence to reduce global warming by relying, I can't remember the exact words, entirely on the science, rather than political arguments or economic arguments. I was wondering if you thought it was possible to make a decision strictly on the scientific evidence, without considering potential societal consequences, that there is a kind of cost-benefit tradeoff. Is there sufficient scientific evidence to take a given policy proposal that may have economic gains or economic losses, and both of you cursorily touched on this [by saying], well, I think this would not be economically harmful, or I think it would be. Dr. Michaels, you suggested zero, that there would never be any rationale to do this . . ."

Patrick Michaels: ". . . The question is at this time. Excuse me . . ."

Audience member: "Can we decide this scientifically alone, or do we have to look more at the societal consequences?"

James Hansen: "I have always said from my first public statements until now that I think we should take those steps which make good economic sense anyhow. There are a lot of ways that we could improve energy efficiency and reduce the emissions of greenhouse gases, with no economic cost. I'm not an economist, there are people who can make the argument and present the facts much better than I can. But that's one comment. I also think that we need to encourage technologies that may be needed in the next century, because it takes several decades to replace energy systems. If we start down a path in which fossil fuels are going to be the replacement fuel as oil begins to be depleted in the next few decades, and there is some disagreement on exactly when that will be, but clearly there are limitations, geologically, on the oil supply. Then we could get into a situation in which we're forced to have eventually very large increases in CO2. And so the two things I recommend are do those things that make good economic sense anyway, and pay some attention to investing in possible long term energy sources that don't produce greenhouse gases" (italics added)

Later in the forum (p. 173), Hansen elaborates further on these themes in language that seems consistent with his 2006 "gives urgency to discussions" phasing referenced in this thread's initial post:

"Now let me go to my last affirmative closing argument. I'll say that the scientific community has looked at the greenhouse issue for a long time, with major reports over at least two decades, from the Charney report, through the IPCC reports. The vast majority of the relevant scientific community believes that even though it is a very complicated issue, with many uncertainties, the evidence is compelling enough that we should take steps to slow down the experiment, while we try to understand it better. Perhaps the most important point is that we should encourage competing technological developments. It takes, as I said, decades for energy infrastructure to be developed and replaced."

Finally, interested readers may find David Hingstman's response comments (pp. 176-179) on the AARST forum illuminating - he makes the salient point that in these matters, the boundary lines demarcating the science/policy distinction are often difficult to pin down.

# 5 | Luke Lea | January 31, 2006 5:41 PM

Instead of "discussions about how to slow greenhouse gas emissions," Hansen should have said something like, "explore all possible strategies to minimize the threat to human welfare posed by global warming," without priviledging one strategy over others.

Cost/benefit estimates will clearly be required to decide what the best policy mix might be, and these will need to be periodically updated to reflect advances in the science of climate change along with advances in all relevant technologies.

Why is the climatological community so resistant to such an obvious truth? It is irrational and is undermining their credibility.