Not even partially correct

Since I’m up early and waiting for the rest of the family to rise, I thought I might comment on this Miranda Devine article which claims that Perth electrical engineer’s discovery will change climate change debate (H/T Ben Cubby and Ketan Joshi on Twitter). The electrical engineer is David Evans, who is married to Jo Nova. The reason that I thought I would comment is that I spent some time on Bishop Hill pointing out to him that his discovery was no such thing. I won’t link to it because I managed to make a rather embarassing – but acknowledged – blunder myself at the end of that comment thread (you can probably find it if you wish :-) ).

David Evans has a whole series of posts on Jo Nova’s blog where he discusses his discovery. I’ll just comment on the aspect that I was discussing with him and which he discusses in this post. He says

The basic model relies heavily on partial derivatives. A partial derivative is the ratio of the changes in two variables, when everything apart from those two variables is held constant. When applied to the climate, this means everything about the climate must be held constant while we imagine how much one variable would change if the other was altered.

As far as I’m aware, this is simply untrue. A complex GCM certainly solves a set of partial differential equations, but these are the standard Navier Stokes equations which are evolved in time and space; it doesn’t, however, require holding everything constant while we check how one variable changes if another is altered. The model simply evolves all the different variables with respect to t, x, y and z.

The most basic climate model, on the other hand, doesn’t use partial differential equations at all; it normally simply evolves the change in temperature on the basis of a forcing time series and a feedback response that is typically assumed to depend linearly on temperature. You can introduce non-linearities and make them more complex, but even basic climate models don’t solve the partial differential equations that David is claiming that they use.

What David Evans appears to be referring to is how one might determine – for example – the feedback response from a climate model. One may indeed do so by holding everything constant, bar one thing, and then determining how the system responds to a change in another variable, such as temperature. However this does not mean that a climate model is evolving this type of partial differential equation; it simply means that this type of equation is used to analyse the output from a climate model. I encountered a similar issue when I had a discussion with Monckton a while back; confusing how one might analyse the results from a climate model, with how a climate model is actually run. Could there be a link?

So, as far as I can tell, David Evans’s startling discovery is simply him being confused about how climate models actually work. Miranda Devine’s article includes that

Dr Evans is an expert in Fourier analysis and digital signal processing, with a PhD, and two Masters degrees from Stanford University in electrical engineering, a Bachelor of Engineering (for which he won the University medal), Bachelor of Science, and Masters in Applied Maths from the University of Sydney.

Not only did David Evans bring up his qualifications in our discussion on Bishop Hill, but his expertise in Fourier analysis and digital signal processing doesn’t seem to have helped him in the past. What Miranda Devine’s article mainly illustrates is that some people will promote anything as long as it appears to suggest that there are major problems with climate science, even if it is written by someone who seems to thinks that where they got their PhD is somehow relevant. Some might call that irresponsible.

Posted in Climate change, Climate sensitivity, ClimateBall, Science | Tagged , , | 87 Comments

How we save nature

Maybe I should stop discussing Ecomodernism, but I do find it interesting and I do think that there are aspects of it that are worth taking seriously. It’s really a pity that it’s being promoted and presented in a way that is likely to alienate many who would like to engage with it.

Today I watched Michael Shellenberger’s recent TED talk (the video for which is at the end of this post). I was more impressed than I expected to be. The last part was a bit of a sales pitch for nuclear – which was maybe a bit more positive than is actually warranted – but I do think that nuclear will almost certainly play a crucial role in future energy production. It might not be quite as easy and straightforward as Michael Shellenberger’s talk seemed to suggest, but being optimistic is not necessarily a bad thing.

The main theme of his talk, however, was about how we’d save nature. One key point was that we save nature by no longer needing it. For example, we saved the whales by finding an alternative to whale oil. I understand what he’s getting at, but it just seems remarkably dismissive. We didn’t specifically plan to save the whales; it just happened because we no longer needed to kill them? It almost suggests that we would have just simply kept going if we hadn’t found some kind of alternative.

The other problem I have with this framing is that it seems to largely ignore why the whales needing saving in the first place; it’s because we almost wiped them out. Finding an alternative to whale oil that then meant we did not need to keep killing whales, is not really the same as saving them. I agree with the idea that modernisation and technology development can help us to decouple from, and to minimise our impact, on nature, but framing this as a way to save nature – rather than as a way to stop us from destroying it – seems to be a somewhat rose-tinted way of looking at this. I also think that we can learn from what has helped us in the past to minimise our impact on nature, as well as learning from what got us to the point where minimising our impact became a necessity.

On the other hand, I do broadly agree with the general idea; modernisation and technology development can allow us to no longer need nature, and can allow the parts that we have used to recover and possibly thrive. We find alternatives to what nature has been providing; oil from fossil fuels, rather than whales; natural gas instead of wood and charcoal; nuclear instead of fossil fuels. However, in my view, this general idea doesn’t scale; it might be true that we can save parts of what we regard as nature by no longer needing it, but we can’t do this for the planet as a whole. We don’t have another planet; we can’t save the planet by no longer needing it, because we will almost certainly need it for the foreseeable future.

On that note, Bill Borucki – who recently won the Shaw prize for Astronomy and donated some of the prize money to the Union of Concerned Scientists – has spent his career searching for planets around other stars, and says

While we can detect other worlds, we cannot go to them. Our future is here on Earth and we must do much more to ensure that our planet’s climate remains hospitable.

As it stands, we’ve currently confirmed nearly 2000 planets around other stars and have a few thousand other planetary candidates. To date, however, we know of no other habited planets and don’t even know of any that could potentially be habitable. Even if we did, the distances are so vast, that getting to another planet is – at the moment at least – virtually impossible. For all we know, a thin shell around a small rocky object, orbiting a pretty standard star, in the outer parts of a spiral galaxy, is the only place in the universe where life exists. Even if this isn’t the case in reality, it may as well be as far as we’re concerned; it’s essentially the only place we have.

So, I don’t disagree with the general theme of Ecomodernism; modernisation and technology development will almost certainly be crucial. However, that this will be necessary does not mean that it will be sufficient. Finding past examples where modernisation and technology development helped us to “save nature” does not mean that if we modernise and develop technology that it will – by definition – “save nature”. To be fair, Michael Shellenberger did get more specific towards the end of his talk when he promoted nuclear as a way to reduce carbon emissions. Of course, that nuclear is an energy source that could substantially reduce carbon emissions does not mean that it is possible to implement it on a timescale that would, by itself, be sufficient. It’s one thing to have an ideal solution, but another to have one that we can realistically implement on relevant timescales.

Anyway, I’ve said more than enough. The video of the talk is below, so it would be interesting to get other people’s views. I should also make clear that this is what I took from it. If anyone thinks I’ve misunderstood – or misrepresented – what was presented, feel free to point out why.

Posted in advocacy, Climate change, Global warming, IPCC, Science | Tagged , , , , , , | 37 Comments

Mark Carney’s speech

Mark Carney, the Governer of the Bank of England, gave a pretty impressive speech a couple of days ago. You can read the speech yourself, but I thought I would use it to highlight more of what I was getting at in my post about Emission Reductions.

Mark Carney says the following in his speech:

The challenges currently posed by climate change pale in significance compared with what might come. The far-sighted amongst you are anticipating broader global impacts on property, migration and political stability, as well as food and water security.

So why isn’t more being done to address it?


We don’t need an army of actuaries to tell us that the catastrophic impacts of climate change will be felt beyond the traditional horizons of most actors – imposing a cost on future generations that the current generation has no direct incentive to fix.

That means beyond:

the business cycle;
the political cycle; and
the horizon of technocratic authorities, like central banks, who are bound by their mandates.

The horizon for monetary policy extends out to 2-3 years. For financial stability it is a bit longer, but typically only to the outer boundaries of the credit cycle – about a decade.

In other words, once climate change becomes a defining issue for financial stability, it may already be too late.

The basic point that he seems to be making is that we live in a society where, at most, we think a decade ahead. The problem with climate change is that its timescale is longer than that; what we do now will likely have little obvious effect in the next decade, but will impact what happens in the decades beyond that. However, if it appears as though things are okay now, and we can’t see any reason to do anything unless we’ll see impacts in the next decade, then our general tendency will be to simply wait until it’s more obvious that we should be doing something.

Stocker_1The issue, however, is related to the figure on the right, that I discussed in my earlier post on Emission reductions. The figure is based on a basic calculation that assumes a mid-range Equilibrium Sensitivity (about 2.5oC per doubling of CO2), that we increase emissions at a rate similar to that for RCP6.0 (for the next few decades anyway) and that we then reduce emissions at the rate shown on the y-axis, starting in the year shown on the x-axis.

For these assumptions, the figure shows that if we started today to reduce emissions by 1%/year, we could keep peak warming below 2.5oC. If we wait till 2040, 1% per year would only be likely to keep warming below 4oC. Keeping warming below 2.5oC would then probably require emission reductions of 5% per year. The longer we wait, the more extreme the reductions will need to be if we wish to have a reasonable chance of keeping peak warming below some level. Of course, we could follow a different emission pathway, and climate sensitivity could be (probably is) different to what’s been assumed. However, the basic picture doesn’t change; the longer we wait before acting to reduce emissions, the more extreme they are likely to have to be.

There is something else to bear in mind. If you spend some time talking to climate scientists, you will probably discover that most would agree that 4oC or more would be pretty catastrophic. As it stands (and as should be pretty clear from the figure above) keeping peak warming below 2oC is going to be extremely difficult, if not impossible; to have a reasonable chance of doing so would require emission reductions of 3%/year, starting now. If we keep increasing emissions till 2030, 3%/year would only give us a reasonable chance of keeping peak warming below 3oC. Keep going a couple more decades and that’s what we’d need to do to just have a chance of staying below 4oC. If we want to be virtually certain of staying below 4oC, we may need even more drastic emission reductions.

So, if starting emission reductions now is potentially economically risky, what will the impact be if we end up being forced to reduce emissions drastically, simply to avoid levels of warming that could have extremely severe impacts? Similarly, for those concerned about risks to democracy, how risky is it to wait and then discover that keeping warming below levels that could have severe impacts, would require doing things that today would be regarded as unpalatable. Of course, we could be lucky, but that doesn’t change that if we aren’t, we could end up being forced to undertake drastic measures.

This post has got slightly longer and more convoluted than I had intended, but I’ll make one further point. None of the above is policy prescriptive; it’s simply what the scientific evidence is indicating; it tells us what level of emission reductions would be required if we want to have some chance of keeping peak warming below some level. It doesn’t tell us that we must do this, but it does tell us what we will probably have to do, if we do recognise that there is a level of warming beyond which the impacts would be so severe that we should avoid it at all costs. Whether emissions reductions are inconvenient, or not, is irrelevant. How our climate responds to increasing anthropogenic forcings depends only on basic physics, not on our values or wishes. We certainly have control over what decisions we make, but we can’t complain if our climate does what we’d rather it hadn’t; it doesn’t care.

Posted in Climate change, Climate sensitivity, Science | Tagged , , , , | 25 Comments

Guest post: The Elephant in the Room

This is a guest post by Lawrence Hamilton, Senior Fellow at the Carsey School of Public Policy, University of New Hampshire.

This will not surprise you, but surveys see an elephant.

Several colleagues and I have a new paper describing results from 35 surveys that asked the same climate-change question. The question is present-tense and neutrally worded. It does not mention policy or the future. One response choice corresponds to the scientific consensus:

Which of the following three statements do you personally believe?
– Climate change is happening now, caused mainly by human activities.
– Climate change is happening now, but caused mainly by natural forces.
– Climate change is NOT happening now.

Figure 1

Figure 1

Respondents can say they don’t know, or decline to answer, but few do. The first three charts in Figure 1 show results from representative US surveys conducted by different researchers, with different methods, in different years (2011, 2012, 2014). In stark contrast to the consensus among active scientists, each of these general-public surveys found just 52 or 53% agreement on the reality of anthropogenic climate change (ACC). The fourth chart pools data from 21 surveys in the northeastern US state of New Hampshire (2010 to 2015). New Hampshire runs a few points higher (55%) than the nation but might not be a bad proxy.

So who agrees with scientists that human activities are changing the climate? Figure 2 breaks down the percentage of now/human responses on New Hampshire surveys by gender, age, education, political party—the usual suspects in survey research—and also by ideology and frequency of watching Fox news.

Figure 2

Figure 2

I often write about political divisions while wishing that I could talk instead about differences among age cohorts or the effects of weather or something else. But politics is the elephant in the room. Whereas evidence for the reality of ACC has brought overwhelming agreement among scientists, in these general-public data liberals and conservatives stand 62 points apart. Only the divisions by other political indicators come close, such as Democrat/Tea Party (58 points) or no-Fox/daily-Fox (49 points); the gender, age and education divisions on climate change are each below 20 points. Moreover, while the reality of ACC is among the most polarized survey questions, other science or environmental topics, from concern about local beach pollution to trust in scientists for information about vaccines, show divisions going in the same direction.

Figure 3

Figure 3

After politics, education is the second-strongest predictor of views on climate. But politics can neutralize or even reverse the effects of education. College-educated respondents more actively assimilate information in accord with their prejudices, whether these prejudices incline them toward scientific or ideological sources. Figure 3 depicts the probability of a now/human response as a function of education and politics (details here). The pattern is reproduced with remarkable consistency across 34 surveys. Among Democrats and Independents, agreement with the scientific consensus rises with education. Among Republicans, agreement with the scientific consensus does not rise with education, and sometimes even falls. This fall becomes steeper if we separate Tea Party supporters into their own group.

Environmental sociologists Riley Dunlap and Robert Brulle, under the auspices of the American Sociological Association, recently edited a book called Climate Change and Society: Sociological Perspectives. Sociological perspectives lie outside most scientific reports on climate change, even those from interdisciplinary groups with a “human dimensions” component. The reason partly involves that elephant in the room, unseen in physical data and hard for physical scientists to address—yet unmissable in society and social data. As Dunlap and Brulle summarize,

The problem is that despite climate change having never come close to being a consensual, post-political issue in the United States—with fossil fuels and many other corporations and now nearly all of the conservative movement challenging its reality and opposed to acting to limit it—key actors concerned about the issue seem to act as if it were. Thus, government agencies sponsoring and funding climate science and response efforts (epitomized by the USGCRP), foundations funding “climate work,” most national environmental organizations, many scientific organizations, many climate scientists, and individual citizens acting to “save the climate” all tend to downplay if not ignore the extreme degree of conflict and polarization surrounding climate change in the U.S.

Postscript: Same elephant, different day

Last week (9/17 to 9/23) a routine political poll asked more than 700 New Hampshire residents who they favored in the coming presidential primaries, also posing some hypothetical questions like this:

Suppose the 2016 presidential election was being held today and the candidates were Donald Trump, the Republican, and Joe Biden, the Democrat, who would you vote for?

Coincidentally, the same poll also carried several science questions like this one:
Which of the following three statements do you think is more accurate? Scientific measurements have confirmed that in recent decades, the concentration of CO2 or carbon dioxide in the Earth’s atmosphere is increasing, decreasing, or staying about the same?

The upper chart in this graphic plots the race. The lower chart compares supporters of the two candidates and finds a 34-point gap in what they believe about CO2.

Posted in Uncategorized | 118 Comments

Emission reductions

I wanted to mention a Thomas Stocker paper called The Closing Door of Climate Targets. I came across it thanks to Paul Price, on Twitter. It’s an attempt to illustrate what we would need to do in terms of emission reductions to achieve certain targets, and what targets become unachievable if we wait too long. It’s quite a nice little calculation since it is quite simple, but one should always be a little careful given the uncertainties in climate sensitivity and carbon cycle feedbacks.

The basic idea is to assume that our emssions grow at some rate r until a time t_1 and then are reduced at a rate s. One can therefore express the emissions as

E(t) = E_o \exp^{r ( t - t_o)}, \ \ \ t < t_1

E(t) = E_o \exp^{r (t_1 - t_o)} \exp^{-s(t - t_1)}, \ \ \ t \ge t_1,

where E(t) is the emissions at time t, E_o is the emissions today (about 9.3 GtC/yr), r is taken in Stocker (2013) to be 1.8%/year, and s is the rate at which emissions are reduced. The next step is to determine the cumulative emissions, because the amount of warming depends almost linearly on cumulative emissions. The cumulative emissions are

C = C_o + \int_{t_o}^\infty E(t) dt,

which can be solved to give

C = C_o + E_o \left( \dfrac{1}{r} + \dfrac{1}{s} \right) \exp^{r(t_1 - t_o)} - \dfrac{1}{r} E_o,

where C_o is the cumulative emissions today (530 GtC).

The equilibrium warming due to cumulative emissions C is somewhere between \beta = 1.3 and 3.9oC per 1000 GtC (Equilibrium Climate Senstivities of between 1.7oC and 4.8o – if I’ve done the conversion correctly. I also think this includes some carbon cycle feedback uncertainty). To get the equilibrium warming you then use

\Delta T = \beta C.

You can also estimate an effective minimum temperature limit by assuming that the fastest emission reduction rate would fix the cumulative emissions at the level when t = t_1. I think there is a slight subtlety that the paper doesn’t quite get; if emissions were halted completely, then atmospheric concentrations would drop and warming would largely cease; warming to equilibrium requires reducing emissions to the level where atmospheric concentrations are fixed. This, however, requires such a low level of emissions, that it is probably a reasonable representation of the minimum level of warming. The result is

\Delta T_{min} = \beta \left[ C_o + \dfrac{1}{r} E_o \left(\exp^{r ( t_1 - t_o)} - 1 \right) \right] = \beta C_1.

Stocker_1So, now you have a set of fairly basic equations that you can use to determine relationships between rates of emission reduction, start year of emission reduction, and climate sensitivity. For example, the figure on the right shows the contours of peak warming plotted against start year and rate of emission reduction, assuming \beta = 2oC per 1000 GtC, and r = 1.8%. Even now, to keep warming to 2oC would require reductions of > 3% per year. Beyond 2030, it becomes virtually impossible.

You can also consider the rate of emission reduction that would be required to meet a particular target. This is shown in the left hand panel of the figure below. For example, waiting till 2040 before starting to reduce emissions, would require annual reductions of 10% to keep warming below 2oC. It also shows what isn’t possible. For example, beyond 2050, 2oC is no longer possible. The right panel shows the minimum achievable target, for different \beta values, and for different rates of emission increase r.

There are of course a lot of parameters that one can play with. You can try different climate sensitivities, \beta, and different rates of emission increase, r. If you want to consider transient, rather than equilibrium, response then use a range for \beta of between 1oC and 2.1oC per 1000 GtC. Most of the numbers used here are probably reasonable middle values, so one should probably think of the results here as giving us about a 50% chance of keeping warming below some level. The main point, though, is that the longer we wait, the more extreme the emission reductions will need to be if we realise that we should be aiming to keep warming below some preferred level, and the more likely it becomes that some targets will effectively be no longer possible.

Posted in Climate change, Climate sensitivity, Science | Tagged , , , | 65 Comments

Guest post: Invitation to participate in a PhD research project on climate blogging

As should be obvious if you read the post, this is a guest post by a PhD student who is looking for people who comment at, or read, scientist-produced climate blogs, to volunteer to be interviewed as part of his research project. He is also interviewing those who run these blogs and has interviewed me via email and in person. I don’t think it is my place to encourage others to take part, or not, but it seems to be an interesting project and I had no mis-givings about taking part myself.

Guest post: Invitation to participate in a PhD research project on climate blogging

My name is Giorgos Zoukas and I am a second-year PhD student in Science, Technology and Innovation Studies (STIS) at the University of Edinburgh. This guest post is an invitation to the readers and commenters of this blog to participate in my project.

This is a self-funded PhD research project that focuses on a small selection of scientist-produced climate blogs, exploring the way these blogs connect into, and form part of, broader climate science communication. The research method involves analysis of the blogs’ content, as well as semi-structured in-depth interviewing of both bloggers and readers/commenters.

Anyone who comments on this blog, on a regular basis or occasionally, or anyone who just reads this blog without posting any comments, is invited to participate as an interviewee. The interview will focus on the person’s experience as a climate blog reader/commenter.*

The participation of readers/commenters is very important to this study, one of the main purposes of which is to increase our understanding of climate blogs as online spaces of climate science communication.

If you are interested in getting involved, or if you have any questions, please contact me at: s1357656 -at- or G.Zoukas -at- (Replace the -at- with the @ sign)

*The research complies with the University of Edinburgh’s School of Social and Political Sciences Ethics Policy and Procedures, and an informed consent form will have to be signed by both the potential participants (interviewees) and me.

Posted in Science | Tagged , , , , , , , , | 3 Comments

Some advice for the Global Warming Policy Foundation

I’ve had a brief series of posts that I collectively call helpful tips for the Global Warming Policy Foundation (GWPF). They’ve included Really, Benny Peiser, Really?, Come on, Andrew, you can get this, and Matt Ridley, you seem a little too certain!. Mainly they’ve focused on situations where people associated with the GWPF have managed to mangle some bit of science. Given their focus, you might expect them to do better, but considering who’s on their Academic Advisory Council it’s no surprise that they mostly get it wrong.

The latest saga is, however, a bit more concerning, given that it is something that you might expect a policy foundation to understand. If you’re going to launch an International Temperature Data Review Project there are a couple of things you might consider before actually doing so. Is there actually something to review? Will you get submissions that are worth considering? The answer to the first question is almost certainly no. The answer to the second is almost certainly yes, some will be worth considering, but they’ll be mostly telling us we’re wasting our time; the rest will be from utter nutjobs.

So, the problem with such a review is that you’ll probably end up having to wimp out, given that publishing something that essentially says, we wasted our, and everyone else’s, time is probably not worth doing. As Stoat points out, you don’t really expect much from the GWPF, so complaining is not really worth the effort. I certainly don’t expect them to be honest, but utterly incompetent was a bit of a surprise. It’s one thing to be a policy foundation that misrepresents science so as to support your preferred narrative, it’s another to be one that does so in a way that make you seem completely out of touch with reality.

Come on, at least behave in a way that makes it worth people putting some effort into criticising you. Noone’s going to bother if it becomes patently obvious that you’re a bunch of incompetent buffoons. At least have some self-respect!

Posted in Climate change, ClimateBall, Comedy, Satire | Tagged , , , , , , , , | 46 Comments