There exists one special category in the taxonomy of contributors to online discussions that tends to be especially annoying when rights of societal groups or more generally policies are considered: the so-called concern-troll. However, the following isn’t about this category of online characters, but the feminism 101 recently made me think about this person who “only has a question, he/she wants to have answered before he/she agrees with you” which then resulted in the following random thoughts. To be honest, I get the impression I’m rather close to a concern-trolling position in a number of discussions.
The following is just a loose collection of my thoughts. It simplifies some issues, it isn’t really based on evidence, it is colored by subjective impressions and values. So let’s start.
In the debate on climate change, the opposition to the assumption, that there is a problem, has two rather prominent phenotypes. The first says “there is no problem, because …”, the second wonders, “what if … (X takes place or Y is the case)” and “shouldn’t we … (wait for more evidence)”.
On the face of it, neither nowadays doubts that there is such a thing as a greenhouse effect or an anthropogenic contribution to climate change. The no-problem-group often proposes, the observed warming is mostly due to the sun, or that natural variability is much larger than we allow for. A related but possibly rarer argument is that the earth system (or only the climate system) is to such a large extent thermoregulatory homeostatic that the anthropogenic disturbance doesn’t matter.
Is the sun responsible for the warming trend in the industrial period? I don’t think so. From my point of view, the evidence for an overwhelming solar influence is at least weak, possibly contradictory, and often built on sand. To put it differently, proposed mechanisms may explain weather-fluctuations and also part of the (natural) climate variability but fail as hypotheses for long-term centennial scale trends. However, as long as the solar community is arguing about the evolution of solar forcing even for the 20th century and more so over the common era and the holocene, there is uncertainty. This is one uncertainty where the climate science community relies on the status quo of confident assessments of another community.
Is the natural variability larger than we thought? Looking at the internal variability in one specific coupled general circulation model, one could state, no it’s even smaller, but that would mislead. More generally my impression is that the high-frequency inter-annual variability is probably in the range of what we know or even smaller, but the low-frequency decadal to multi-decadal variability is possibly indeed more influential on decadal scales than we thought. However, this question is going to remain unanswered lacking sufficient long term data. While the North Atlantic multi-decadal variability has been the focus of research for the last 50 years, less time has been spent on the mechanisms of low-frequency variability in the North Pacific. Assuming low-frequent climate modes mask the warming signal in the 2000s we also have to allow for a possible amplification of the warming signal. For example, a talk by Julia Slingo recently emphasised the possibility of a role of the Pacific decadal oscillation in the lack of recent surface temperature warming. She further noted that if we accept this as a possibility we also have to allow for a similar role in the rapid 1990s warming. The question then becomes, how and where does the North Pacific and the atmosphere exchange heat and how does this relate to other ocean basins. Therefore, we need model simulations and better observations. Such internal variability superposes the observed, very likely forced long term trend.
What about thermoregulatory homeostasis? One view of a thermostat mechanism is based on Lindzen’s idea of a tropical iris effect. This “remains an intriguing hypothesis—neither proven nor disproven”. There’s a second perspective on this, which, in my understanding, is to some extent founded in Lovelock’s Gaia. Relying on a superficial reading of Axel Kleidon’s work, I acknowledge that the possibility of such a system exists. Nevertheless, its use in discussions appears to be either founded in some teleological ideas or in wishful thinking. My question is – and maybe I’m just to lazy to search for an answer – on which time-scales do we expect the self-regulation to start? My understanding is, we do not expect a quasi-instantaneous self-regulation but it is supposed to work on longer up to multi-millennial time-scales.
The what-if-group appears to have (at least recently) adopted the lukewarmer-lable, though I wonder whether they really subscribe to the definition provided by Steven Mosher (“Equilibrium climate sensitivity [ECS] is very unlikely less than 1.2; the median estimate is 3C). The what-if questioning concentrates possibly on two points with respect to science. On the one hand, the position also refers to the possibility that (the importance of) natural variability has been underestimated, on the other hand they ask what would be the consequence of an ECS of (e.g.) ~1.5°C? The latter question implies, that the politically (but not necessarily emotionally or scientifically) accepted threshold of dangerous climate change (2°C) is unlikely to be breached within this century. If this is the case, shouldn’t we then wait (until science is clear about ECS, and future generations are likely to be better equipped to deal with any potential problems for a second doubling due to technical progress)? This indeed is probably the core of the climate change, policy, and uncertainty dissens.
As noted, the 2°C goal is not so much a scientifically motivated limit but a value judgement. Dangerous climate disturbances might be expected for various magnitudes of warming in different locations and regions. The global number does not account for this. However, such an argument implies shifting a politically adopted goalpost only for convenience’ sake. So let’s assume 2°C is a magical number, and ECS is 1.6°C. What does that mean in all it’s simplifications. We’d expect an equilibrium response of 1.6°C at atmospheric CO2 concentrations of 560ppm and 3.2°C for 1120ppm. This would happen (according to RCP 8.5) sometimes during the 22nd century, and I think RCP 6.0 would also allow for a 2°C warming assuming such an ECS. That is, I don’t believe ECS equalling 1.6°C is a turning point. Nevertheless it shifts the 2°C perspective further to the future.
All the above questions boil down to the question which evidence policy-making evaluates or should evaluate to come to decisions. Which uncertain and discussed hypotheses have to be explicitly included and which may be just considered as general uncertainty – uncertainties that usually go both ways. It’s not only the question whether the problem may be smaller than proclaimed; it may as well be larger than thought.
But anyway, the above statements do imply that we can wait, don’t they? Future generations are likely better equipped to deal with the potential problem, aren’t they? Our research and knowledge is going to help them, isn’t it? At least it doesn’t hurt to wait until 2030 with decisions and implementations until 2050, does it?
The logic appears faultless taking the questions not as expression of uncertainties which also go to the other direction but as expression of “my position is more likely than not to be the case, isn’t it”. Nevertheless, my major concern against it isn’t even contradicting it: This is not the decision of the loudspeakers regardless of whether they are rather sceptical about the problem of anthropogenic global warming or whether they see it as one of the biggest problems humanity has to deal with. The decision is a political one. Ideally it is made democratically locally, regionally, nationally and supranationally. My second concern is also not founded in anything but my personal values. Let’s say we accept that our CO2 emissions have an influence on the climate and thus on our or our descendant’s living situations (and possibly the environment as well), and that this is going to be a problem at some point in the future. Then, I can’t see any good reason why we shouldn’t try to minimise our contribution to this problem after considering all the available (uncertain) evidence on impacts and vulnerability, mitigation and adaptation. So my assumption is, anthropogenic climate change is going to be a problem for some people at some point in the future, and therefore we have to decide in some democratic or demoicratic whether, when and how we have to deal with this problem.
Yes, this implies applying the precautionary principle in some weaker or stronger definition. Thereby it is important, that the decisions on “a credible threat of harm” are based on “the fullest possible scientific evaluation, the determination […] of the degree of scientific uncertainty; a risk evaluation and an evaluation of the potential consequences of inaction; the participation of all interested parties […]”.
Of course, the question arises whether I am a hypocrite and don’t care about my personal behavior and contributions to solving the possible future problem. That is: do I fly too much (yes, although I rarely travel by air), do I use my car too much (most certainly), and can I generally reduce my personal footprint (definitely, although it should be already rather average or even small relative to Germans in general); and what about other environmental (chemical production and usage, or foot production and waste) or moral issues (hunger, poverty)? These are very good questions.
14ter Stock 
I like the terminology of ‘there is a problem’ and ‘there is no
problem’ people – it’s a good place to start from and nobody can be offended.
The difficulty that the ‘problem’ people have is there are so many levels of the ‘no problem’ argument, and each ‘no problem’ person emphasizes different combinations of these.
First there is the ‘temperature records have been adjusted to cool the past’ argument, which is hard to argue against when the Iceland Met Office states that the cooling adjustments applied by GHCN are wrong.
Then there is the natural variation argument. We simply don’t know how large the natural variation is on different timescales, and this is a question that models are unlikely to be eable to answer. I agree that the low-frequency variability is probably
under-represented in the models (maybe just simply because the models are so over-damped).
The regulation argument does not just depend on woolly Gaia
ideas. It’s simple physics. Hot air rises. Higher temperatures lead to more evaporation and hence cooling. These are simple negative feedbacks.
Then there is the ‘low sensitivity’ or ‘climate models overestimate the effect of CO2’ argument. The complete failure of recent climate model predictions (eg the Met Office prediction of 0.3C from 2004-14) supports the ‘no problem’ view here.
Finally there is the ‘warming is beneficial’ argument.
From ancient times until the 1970s, it was generally acknowledged that warm was good and cold bad (see for example the conclusions of the famous Callendar paper, or climate textbooks written up to the 1970s).
Only in the recent years of global warming hysteria has this been reversed.
Finally finally is the ‘damaging and pointless’ argument made by Robin Guenier and often by Barry Woods. Damaging – think of the biofuels mess, the destruction of the environment by wind turbines, the poverty caused by high fuel bills thanks to green taxes etc; and pointless – because no world agreement
is going to be reached so a unilateral gesture from a small country
like the UK is pointless in view of what is happening in India and China.
The bottom line is that if they expect people to make drastic changes to their lifestyle, the ‘problem’ people have to make a convincing case, and at the moment they have utterly failed to achieve this.