He argued that it’s best to be explicit about one’s values and clearly distinguish when one is talking values (“ought”) and when one is talking science (“is”). I entirely agree. I would add that it’s important to distinguish recommending a generic (e.g. mitigation) vs a specific (e.g. CCS) course of action, especially when the latter is not one’s area of expertise. I wrote about the public role of scientists before, which touches on many of these same issues.
Judith Curry also chimed in, complimenting Gavin but also giving some criticism, much of which is rather off-base imho.
Both Gavin and Judith refer to this statement by Thomas Stocker at the end of the (well worth watching) IPCC AR5 video:
Continued greenhouse gas emissions cause further climate change and constitute a multicentury commitment in the future. Therefore we conclude that limiting climate change requires substantial and sustained reductions in greenhouse gas emissions.
Is this a normative statement (“ought”) or a factual statement (“is”)? Gavin claimed it’s the latter, Judith claimed it’s the former. It would be advocacy if the goal was left out, as in “we should reduce GHG emissions”. But that’s not what Stocker said. Instead, what he said comes down to “if this is the goal, then that is what needs to be done to achieve it”. Curry claims that adaptation, carbon sequestration or geoengineering would also be options to limit climate change. That’s only partly true. Adaptation doesn’t actually limit climate change, as the word says it means adapting to climate change. As such it helps in the short term (and is definitely important), but in the long term adaptation without mitigation is like mopping the floor while leaving the tap running (see also the Rabett). Carbon sequestration is a viable option to reduce atmospheric concentrations, but with current technologies it can only make a minor contribution. So it could limit climate change to a very limited extent one might say. Geoengineering is a more complicated story. Basically, it exchanges one type of climate change (temperature changes) with another type (hydrological changes), so it changes climate change.
Perhaps Stocker’s statement could have been made more specific by including e.g. something like “limiting climate change to what societies are adapted or can adapt to requires substantial and sustained reductions in GHG emissions” which I think is what he meant anyway.
Curry goes on to state ” And there is a missing element in this argument that warming is ‘bad’, which is a value judgment and has nothing to do with science.”
This is a strawman argument, as it’s not a (hidden) element in Stocker’s argument as given above. Again, it would be true if the goal was omitted or left implicit (but it wasn’t). If one feels that limiting climate change is not needed (because it’s not bad) than the needed cure (reducing emissions) is not needed, obviously. That is entirely consistent with what Stocker said.
Curry further offers the following list of “examples of potential hidden values that are rather inconvenient (because) these are why the public distrusts scientists as advocates”. I offer my comment with each (in italics). It’s not at all clear that these would all go in the direction of a bias in favor of the mainstream (as Curry seems to implicitly assume); to the contrary.
- personal career advancement: Unclear in which direction this would most likely go.
- research funding: idem, though this could cause a tendency to increase the apparent magnitude of uncertainties.
- the value in terms of professional recognition (e.g. awards from professional societies) that supporting the scientific consensus can provide (recognizing the ostracism that con result from straying): No bigger reward for a scientist than to prove the scientific consensus wrong.
- media attention: This goes in the direction of providing relatively more media attention to contrarian voices, Judith Curry herself being a good example (assuming that she wasn’t as prevalent in the media before her U-turn away from mainstream science). This got confirmed in the large survey amongst climate scientists that I conducted last year (not yet published).
- influence within the scientific community: This hinges on using solid arguments, so usually provides the correct incentive.
- influence at the power tables in terms public policy: Like with media attention, extreme voices seem to have disproportionate influence. Look at the regular line-up for US senate hearings for example. If you crave media attention and political influence, being loudly contrarian is a sure way to achieve that. In the Netherlands the same tendency is apparent.
- broader political objectives that support any/all of the above: This goes more likely in the direction of downplaying rather than overplaying AGW I would argue.