Climate change as a matter of risk management requires different choices in communication

Rowan Sutton just published a very short article (an “idea”) in ESDD entitled “a simple proposal to improve the contribution of IPCC WG1 to the assessment and communication of climate change risks”. From a risk management point of view a focus solely on the most likely outcome is not recommended, especially when the impacts increase sharply towards one end of the scale.

Sutton:

A common measure of risk is likelihood x impact (Fig 1). It is standard practice in risk assessment to highlight both the most likely impacts and low likelihood high impact scenarios. Such scenarios merit specific attention because the associated costs can be extremely high, so decision makers need to know about them. It follows that WGI has a responsibility to assess and communicate explicitly the scientific evidence concerning potential high impact scenarios, even when the likelihood of occurrence is assessed to be small. In past reports the assessment of key parameters by WG1 has focussed overwhelmingly on likely ranges only. When information has been provided about the tails of distributions only likelihoods have been communicated using terms – following the IPCC’s uncertainty guidance (Mastrandrea et al, 2010) – such as “very unlikely” or “extremely unlikely”: a clear steer that policy makers should largely ignore such possibilities. But this is wrong. Policy makers care about risk not likelihood alone. The IPCC’s uncertainty guidance ignores impact and is symmetric with respect to high or low impact scenarios; this is inappropriate for the communication of risk (Fig 1).

Figure 1: A schematic representation of how climate change risk depends on equilibrium climate sensitivity (ECS).

Some will argue that the WGII report is needed to provide information on impacts. For detailed information this is certainly the case, but the general shape of the damage function for a large basket of impacts (Fig 1) is insensitive to such details, and is all that is needed to justify WGI providing a much more thorough assessment of relevant scenarios. Other critics will suggest that for WGI to identify high impact scenarios explicitly would constitute scaremongering; this concern is no doubt one reason why previous WGI reports have focused so much on the likely range. But it is misguided. Policy makers need to know about high impact scenarios and WGI has a responsibility to contribute its considerable expertise to making the appropriate assessments.

A very similar point has been made by Kerry Emanuel in his post “Tail risk vs Alarmism” on CCNF:

In assessing the event risk component of climate change, we have, I would argue, a strong professional obligation to estimate and portray the entire probability distribution to the best of our ability. This means talking not just about the most probable middle of the distribution, but also the lower probability high-end risk tail, because the outcome function is very high there.

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But there are strong cultural biases running against any discussion of this kind of tail risk, at least in the realm of climate science. The legitimate fear that the public will interpret any discussion whatsoever of tail risk as a deliberate attempt to scare people into action, or to achieve some other ulterior or nefarious goal, is enough to make almost all scientists shy away from any talk of tail risk and stick to the safe high ground of the middle of the probability distribution. The accusation of “alarmism” is quite effective in making scientists skittish in conveying tail risk, and talking about the tail of the distribution is a sure recipe to be so labelled.

Hans Custers schreef een kort Nederlandstalig blog over Sutton’s artikel.

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IPCC SRREN: Conflict of interest or just a bad press release?

The blog discussion of the week seems to be about IPCC’s Special Report on Renewable Energy Sources and Climate Change Mitigation. Question is, has a study headed by a Greenpeace employee been overly hyped? I think the short answer is that it has in the press release but it hasn’t in the underlying report.

One would think that that would be the end of it. It’s become the norm that press releases highlight an eye catching finding rather than trying to paint a full picture of the underlying report. The former draws media attention; the latter does not. Media need a news hook after all, as we’re frequently told by journalists. That’s not necessarily a good thing for science journalism and science literacy, but it’s the case nevertheless.

Then why does the bulk of the criticism go to the whole of the IPCC process? That’s a bit of a rhetorical question of course, as the answer is fairly obvious: There are legions of people looking for excuses to throw the IPCC under the bus. And sometimes even people who have a decent understanding of the issues are enclined to support such efforts, if they become convinced of serious wrongdoing. Think Monbiot with regards to “climategate” and now Mark Lynas with the SRREN. Mind you, I think the questions that Lynas posed to the IPCC are fair and deserve to be answered:

Here, repeated, are the questions I have posed to the IPCC’s Edenhofer:

1: what was the process for writing the press release, and who decided whether it faithfully represented the main conclusions of the SPM/main report?
2: why was the SPM released more than a month before the full report?
3: was Sven Teske in any way involved in the decision to highlight Teske et al, 2010 as one of the four ‘illustrative scenarios’ explored in greater depth as per Section 10.3.1?
4: what is the IPCC conflict of interest policy with regard to lead authors reviewing their own work, and having affiliations to non-academic institutions, whether campaign groups or companies?

The Carbon Brief has a good rundown of issues. One paragraph though struck me:

the use of word “could” in the IPCC’s press release (“Close to 80 percent of the world’s energy supply could be met by renewables by mid-century”) is likely to refer to future uncertainties, but may well have been perceived by journalists and the public as a straightforward statement about the technical potential of renewable energy.

I think it’s the opposite: I think the word “could” refers to “technical potential” rather than to future uncertainties. As in, if we really wanted to and put the effort (and money) in, this is what we could achieve. Whereas most reading this understand it in the other way and then interpret is as hopelessly optimistic and biased.

I agree that it’s not wise to put a rather unrealistic scenario forward as an example in the spotlights. My point is not so much to argue how silly vs wise, or how realistic vs unrealistic is it, but rather to distinguish that which is technically possible from what is societally and politically realistic. David Keith (in a different context) made some pertinent comments to this:

However when people and the political community hear technical people say “can’t be done” they assume we mean that technically can’t be done and that is untrue and destructive.
It’s destructive because it hides the central moral choice: we could cut emissions if we want to, we could have started decades ago when the scientific warnings about climate change were first raised, but we decided not to. It was a choice, implicit or not. A choice that, in effect, we cared more about current consumption than we did about preserving our grandchildren’s chances to enjoy a climate like the one in which our civilization developed.

McIntyre, in a comment at DotEarth, seems to agree that the central issue is the press release:

Andy, I don’t think that you adequately highlighted that the Greenpeace scenario was the one that was featured in the IPCC press release and covered by the world media. Had the problem been limited to the Chapter 10 discussion, it would be less of an issue.

Which leads Michael Tobis to remark:

It does appear that whoever wrote the press release did a disservice. This seems so common in press reports of science that I am starting to think of it as typical. If Mr. McIntyre had limited himself to such a claim, as he does here, I would have no quarrel with his behavior in this case. But he proceeds, on his blog, to use this incident to call for “Everyone in IPCC WG3 [to] be terminated and, if the institution is to continue, it should be re-structured from scratch.”

Thus he continues to play to the “climate science as fraud” crowd that frequents his blog while adopting a more reasonable pose here.  

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The persistent substitution of fake problems for real ones is a key to derailing serious conversations these days.

The important conversation that we should be having, connected with the issues in the SRREN, is about what kind of future we want.

“Those who want search for a way. Those who don’t want search for a reason.”