Oliver Geden is a climate/energy policy analyst at the German Institute for International and Security Affairs. I’ve written before about Oliver Geden’s views and have, typically, been rather unimpressed by what he presents. He’s even accussed me of misrepresenting him, but I’m still not quite sure how. A few days ago he published another comment in Nature Geoscience called An Actionable Climate Target.
The key message in his comment is:
In the future, the main focus should not be on temperature targets such as 2 or 1.5 °C, but on the target with the greatest potential to effectively guide policy: net zero emissions.
I think there is some merit to this, but there is still much with which I disagree. He also still seems incapable of avoiding having a dig at physical scientists, saying:
The problem-centred approach pursued by physical scientists assumes that appropriate policy action will follow from an accurate definition of DAI more or less automatically.
where DAI means Dangerous Anthropogenic Interference. I really think the above completely misrepresents what physical scientists actually assume. I don’t think that physical scientists believe that appropriate policy will automatically follow from an accurate definition of DAI. In this context, physical scientists are expected to inform, not influence. What they present should be based on the evidence available, not on what will most likely lead to what they (or others) think is the most appropriate policy action.
The information they provide should not change just because the resulting policy does not appear consistent (according to some) with the information presented. In fact, I think it would be wrong if physical scientists were to do so; that the information they present appears to not be being influenced by the resulting policy action is – if anything – indicative that they’re basing it more on the evidence available than on what would most likely influence policy makers.
He then goes on to criticise temperature targets, saying:
Temperature limits are problematic since they create an ‘either/or’ situation: a 2oC limit can be either hit or missed. If climate research showed that failure is likely, this would drastically reduce the motivation of policymakers, companies, non-governmental organisations and the public at large — and would force governments to adopt a less ambitious target immediately.
I guess it is true that either you achieve the target, or not, but it’s not clear that this is a good argument for not, at least, having it. I realise that these temperature targets are somewhat political, and are not really boundaries between everything fine and catastrophe. However, they are regarded as targets beyond which we’d expect the impacts to get increasingly severe, and where the negatives likely outweigh the positives. It’s also my understanding that the 2oC limit was also chosen as boundary beyond which we might pass tipping points where some of the changes would become essentially irreversible.
Hence, even if we are likely to miss these targets, there would still seem to be some value in at least maintaining them so as to remind policy makers that there is probably a vast difference between just missing them, and missing them by a lot. What’s also slightly ironic about Oliver Geden’s suggestion is that it would seem – as I’ll explain below – to be essentially be arguing for a less ambitious target, while claiming that this would be the result of maintaining temperature targets.
He then goes on to argue in favour of a zero emission target, rather than a temperature target:
In contrast to temperature targets, a target of zero emissions tells policymakers and the public precisely what has to be done, and it directly addresses problematic human activity.
Well, I think it is wrong to claim that this tells policy makers and the public precisely what has to be done. This also gives me an opportunity to mention that I went, yesterday, to hear Chris Rapley talking at the Edinburgh Science Festival. He said something that illustrates the problem – in my view – with Oliver Geden’s argument. He mentioned the Paris meeting at which it was agreed to hold the increase in the global average temperature to well below 2oC, while pursuing efforts to limit the temperature increase to 1.5oC. However, he then went on to point out that this requires getting emissions to zero.
In other words, a temperature target already includes that we need to get to zero emissions; stablising temperatures with respect to long-term anthropogenic warming requires that we eventually stop emitting CO2 into the atmosphere. The problem with Oliver Geden’s claim is that a zero emission target alone does not tell policymakers and the public precisely what needs to be done because it is not – by itself – associated with any kind of temperature target. A temperature target, however, is associated with a target of zero emissions.
You might argue that this isn’t clear from a temperature target alone. However, these temperature targets are normally associated with a carbon budget, which is intended to indicate how much more CO2 we can emit if we want a certain chance (normally 66%) of achieving the target. It’s doesn’t take much to realise that if there is a limit to how much more we can emit, that we eventually have to stop emitting (i.e., a carbon budget is explicitly associated with getting to zero emissions).
To be fair, I do think that it is good that Oliver Geden is stressing the need to get emissions to zero. However, I don’t think that this is, by itself, sufficient. The consequences of getting emissions to zero after emitting another 500GtC will likely be vastly different to doing so after emitting another 1500GtC. Admittedly, he does say
every country will have to reach zero in the second half of the century.
which would presumably constrain how much more can be emitted before reaching zero emissions. However, I still fail to see how focusing on zero emissions only is somehow preferable to some kind of temperature target that is then associated with a carbon budget and – as a consequence – a requirement to get to zero emissions. The problem I can see with a zero emissions only target is that it could lead to people thinking that all we need to do is eventually get emissions to zero, which is clearly insufficient. If we think that there is a level of warming beyond which there could be severe negative consequences, then we need to get to zero emissions AND limit how much CO2 we eventually emit.