Greater future global warming?

Before I go out I wanted to briefly mention a recent paper by Patrick Brown and Ken Caldeira called [g]reater future global warming inferred from Earth’s recent energy budget. Patrick Brown already has a nice blog post about this with a couple of really informative videos. I encourage you to read Patrick’s post and watch the videos.

The basic idea, though, was to try and constrain the models on the basis of how well they match recent observations. In particular, how well do they simulate top-of-the-atmosphere energy balance (reflected solar radiation, outgoing infrared radiation, and net energy balance). As Patrick’s post mentions, these are amongst the most fundamental aspects of global warming.

The key result is shown in the figure below. When you constrain the models on the basis of how well the match these observational constraints (pink band, red line), they project more warming than the unconstrained model results suggest (grey band, dashed line), and the range is slightly reduced. For example, if we follow and RCP4.5 concentration pathway, this would suggest we would warm about as much as suggested by the original RCP6 results. Also, the mean ECS value from the constrained models is 3.7oC, with a likely range from 3oC to 4.2oC (right-hand panel below).

Credit: Brown & Caldeira (2017)


Of course, this is simply one study, so one should be careful of simply accepting it. However, it is suggestive and is – I think – not the first time a study has suggested that models that better represent recent observations have higher climate sensitivities than the model mean. This would seem to indicate, as the paper says, that

achieving any given global temperature stabilization target will require steeper greenhouse gas emissions reductions than previously calculated.

Link:
Greater future global warming inferred from Earth’s recent energy budget.
Patrick Brown’s blog post about his recent paper.

Update:
Steve Forden made a good point on Twitter. If you consider the left-hand panel of the figure, the difference between the constrained model results and the original results is not particularly significant for the lower emission pathway. Therefore what I quote at the end of the post is probably not really true for a temperature target of around 2oC (i.e., the result in this paper doesn’t really change what emission pathway we would need to follow to achieve such a target).

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Posted in Climate change, Climate sensitivity, Global warming, Research, Science | Tagged , , , , , , | 57 Comments

Polar Bears and Arctic sea ice

Jeff Harvey, who is an occasional commenter here, is lead author of a recent paper on [i]nternet blogs, polar bears, and climate-change denial by proxy. The paper itself is open access, and if you would like to read some posts about it, Bart Verheggen (one of the authors) has a one, as does Dana in the Guardian.

Essentially, they looked at a large number of blogs, that they categorised as either denying, or accepting, anthropogenic global warming (AGW). They then analysed how these blogs covered certain topics. When it came to Arctic sea ice, those categorised as denying AGW tended to interpret short-term variability as indicating some kind of recovery. When it came to polar bears, those categorised as denying AGW tended to primarily use a single source (Dr Susan Crockford) who – based on their lack of peer-reviewed publications about polar bears – would appear to have undertaken little original research.

This isn’t a huge surprise, but it is interesting to see it documented. Even though it isn’t really a surprise, I do still find it remarkable that so many will promote the contrary claims of someone who appears to have little in the way of actual expertise.

The comment/conclusion in the paper that I found interesting was

We believe that it is imperative for more scientists to venture beyond the confines of their labs and lecture halls to directly engage with the public and policymakers, as well as more strongly confronting and resisting the well-funded and organized network of AGW denial.

I realise that some will probably whine about well-funded but I mostly agree with the idea that it would be good for more scientists to engage publicly and to, more specifically, directly counter misinformation. Partly, the more voices the better, and partly because it would probably be good for more to recognise that many are not engaging in good faith. It’s a little frustrating when some who have never interacted with those who are dismissive of AGW, think they know of some simple way to resolve these disputes; for example, just being nicer is not going to do it (which doesn’t mean don’t be nice, it just means that it’s unlikely to have much impact).

As you might expect, the response to this paper has been somewhat predictable. In an example of extreme ClimateballTM, Tom Fuller has used this paper to suggest that climate scientists harass women (yes, I realise I probably shouldn’t promote it, but it is also been promoted by the Global Warming Policy Foundation so it probably is worth mentioning).

What makes Tom’s post particularly bizarre is that he includes a quote from me about Roger Pielke Jr. When it comes to Roger Pielke Jr, I’m normally being criticised for supposedly attacking him. In this case, however, I’m quoted as saying something positive, which is then used to imply that climate scientists are more restrained when criticising men, than they are when criticising women. Firstly, saying something positive about a man, does not imply less restraint when criticising women. Secondly, I’m not a climate scientists, so my quote has no relevance anyway. Thirdly, there are many reasons why one might not say something positive about Roger Pielke Jr; being worried that it might be used to suggest that climate scientists harass women, wasn’t one that had ever crossed my mind.

Furthermore, Tom Fuller’s post claims that the Harvey et al. paper flat out lies about Dr Crockford’s publication record. The paper claimed that Crockford has neither conducted any original research nor published any articles in the peer-reviewed literature on polar bears. As far as I can tell, this is true (I certainly can’t find any peer-reviewed papers about polar bears on which Dr Crockford is an author, and peer-reviewed papers is the main way in which one presents original research). When challenged, Tom Fuller highlighted a comment posted on a journal’s website about a paper on polar bears. When I say comment I don’t mean something submitted to the journal for review and, possibly, publication, I mean something akin to a blog comment (i.e., written into comment box on a website).

This is getting rather long, so I should probably wrap up. In my view, if someone regards themselves as some kind of world-leading expert, then they really should aim to get their work published in a peer-reviewed journal. It’s not that difficult, given some of the rubbish that gets through. Also, if you’re running a blog that purports to be presenting scientific information about a topic, ideally don’t base everything on one source, especially if that source is someone who has never published a peer-reviewed paper on the topic. Of course, if your goal is to promote a particular agenda, then maybe basing everything on a single source who says what you want to hear is precisely what you should do – feature, rather than bug?

Posted in Climate change, ClimateBall, Research, Scientists, The philosophy of science, The scientific method | Tagged , , , , , , , , | 422 Comments

Science communication – again

There are a number of possible things to write about, but I thought I might have a brief rant about a topic I find of interest. A tweet by David Roberts (who I mostly like) caused a bit of a Twitter storm a couple of days ago.

I actually disagree with him about this specific case; in my view, the Climate Feedback article was pretty good and Climate Feedback generally provides, from what I’ve seen, very good critiques of articles about climate science.

However, I do think that he does make an interesting point. The manner in which scientists critique articles about science should depend somewhat on the role they’re taking. If they’re doing so as domain experts, then they really should aim to critique the scientific validity of the article, not really the way in which it was framed. Given the same information, it may well be possible to present something in an optimistic way, or in a pessimistic way; scientists don’t have some special right to decide how it should be presented publicly. As individuals, however, they are perfectly entitled to express such a view, but they should aim to be clear about their role.

Now, this is where the slightly ranty bit starts (well, as ranty as I can get). This led to me having a discussion with someone who regards scientists (well, climate scientists, at least) as incapable of communicating with a public audience and regards them as being in denial when it comes to cognitive science and narrative theory. Essentially, there is extensive evidence about how to communicate effectively and many (maybe most) science communicators are simply dismissing this information.

I think this is wrong for a number of reasons. Firstly, there are clearly many scientists who are extremely effective communicators. Secondly, these critiques often seem to assume something about the goals of science communication that is almost certainly not the goals of those scientists who undertake such activities. In my experience, most scientists who choose to engage in science communication do so because they regard it as important to make the public aware of scientific information. They do not, typically, regard themselves as responsible for influencing public opinion. Most of the critiques, however, seem to revolve around their inability to influence public opinion. Well, criticising people for not achieving what they were not specifically intending to achieve, seems rather pointless.

Of course, I have no problem with scientists who openly choose to try and influence public opinion; I think they have as much right to do so as anyone else. I simply think that in many cases science communication is aimed more at providing information, than at influencing opinion. Critiquing the former, for not achieving the latter, just seems to indicate a lack of understanding of what motivates many who choose to engage in science communication.

However, the aspect of this that I find most irritating is that if there are a group of people who regard themselves as experts in cognitive science and narrative theory and, hence, how to communicate effectively, why don’t they go ahead and demonstrate this. Treat scientists as their audience and communicate to them so effectively that they not only understand how to communicate effectively, but are convinced that they should actually engage in this way. If this is an important topic that needs to be effectively communicate, and they have relevant expertise that will aid in such activities, then they have as much obligation to communicate this effectively, as scientists with relevant expertise have to communicate their information.

Okay, that’s my mini rant over. Of course, I’m generalising rather wildly. There are clearly a number of very effective science communicators and there are also those who have expertise in cognitive science and narrative theory who are helping to improve the effectiveness of science communication. I just find myself rather irritated by those who seem incapable of communicating effectively themselves, complaining about others they regard as ineffective communicators.

Posted in ClimateBall, Research, Science, Scientists, The scientific method | Tagged , , , , , | 74 Comments

Going Nuclear

An epic tweetspat with pseudo-modern engineers made me think of the following confutation of the Breakthrough playbook:

First, nuclear energy needs to compete with fossil fuels, not renewables like wind or solar. This point rests on the basic observation that the only way to replace fossil fuels is to replace fossil fuels. This point also rests on the idea that the path toward sustainable energy requires more nuclear energy than anything else, a conclusion that seems to be supported by the work of David Mackay [1].

Second, the capital intensity required to go nuclear is quite substantial. The total costs of building nuclear power plants is what matters most. As Bernard L. Cohen says:

It is useless to develop new plant designs if they will be too expensive for utilities to purchase.

Most working American reactors were commissioned before 1975. Investing in nuclear is done over decades. Generations in fact: one builds nuclear plants for one’s grandchildren. Intergenerational justice is involved: if you invest money now for your grand kids, that’s less money for your kids. To estimate that kind of investments, discount rates matter. Institutional investors must step in and play harder than GRRROWTH enthusiasts usually promote.

(A remarkable corrolary is that the more you crank discount rates, the more nuclear becomes costly. So there’s a crucial tension between the pseudo-modern and the lukewarm playbooks. At least Richie’s or Matt King Coal’s version of it.)

Third, even if in small dose can be beneficial, hippie punching is a path of least resistance that can’t stand alone. It won’t reduce carbon emissions, and amounts to the same kind of scapegoating that contains any populist playbook. It’s a distraction, like if APPL started to whine about Linux. The difference of scale shows it’d be tilting at windmills. The alpha to beat is fossil fuels.

Fourth, the main financial obstacle to reduce fossil fuels are subsidies. According to Coady et al 2017, we’re talking about a $5 trillion dollars ballpark worldwide. That’s more than 5% of the global GDP. This is lightyears away from what we give solar and wind. To give you an idea of what we can do with that much money, 0.3% of the world’s 2014 income would be enough to achieve the Millenium development hunger target.

In short, divestment from fossil fuels will be required, whether we go nuclear or not. Hippies are winning more than their caricature make it seems. They at least picked to right target, i.e. fossil fuels, something that still escapes the BTI guys, whose proposition, I duly submit, has been confuted with this note.

I’m all for going nuclear. I live in Canada. Many uranium bases belong to us. I’ve been waiting for a decade now to go long on uranium. But I’m no dummy – I won’t invest in a market that low energy prices could kill in a whim just because gaz guzzlers decide to keep subsidizing fossil fuels.

Kevin Anderson suggests that we’d need 4000 new nuclear plants by 2050 to meet 25% of our total energy consumption. We are building 65. Going nuclear means regulating the energy market for a long time. That doesn’t imply nationalization, although this is tried, tested, and true. I suppose market-based solutions exist: the trick is to make sure corporations are kept in check.

To paraphrase Scott Denning, if Freedom Fighters shirk their responsibility, decisions will be made without them. They had all the time to make themselves heard. So much the worse if they waste everyone’s time punching hippies and tilting at windmills.

And that’s the memo.

[1]: This claim has been revised on 2017-11-29 (17:11 EDT), based on BBD’s suggestions in the comments.

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Combining different ECS estimates

I wanted to briefly highlight a new paper by Nic Lewis and Peter Grünwald called [o]bjectively combining AR5 instrumental period and paleoclimate climate sensitivity evidence. You may want, however, to be cautious of the term objective. As the title indicates, they essentially combine instrumental and paleo estimates for equilibrium climate sensitivity (ECS). However, some care should be taken with this result, since instrumental estimates are essentially effective climate sensitivity, rather than equilibrium climate sensitivity, but I still think this is a really nice thing to have done.

Their headline result basically

provide[s] a 5–95% range for climate sensitivity of 1.1–4.05 K (median 1.87 K),

which is similar to the earlier Lewis and Curry results, but with a slightly higher median.

However, if one considers the figure below, there do seem to be number of slightly different results, depending on the method used. All seem to produce 5-95% ranges of about 1-4K, but the median seems to vary from just below 2K, to just above 2K.

Credit: Lewis & Grunwald (2017)

Roughly speaking, this result seems broadly consistent with the IPCC range of 1.5-4.5K (although that might be a 17-83%, rather than a 5-95%, range), with a slight shift to lower values and a lower median than might be expected. A few general comments, though. Unless clouds happen to provide quite a strong negative forcing, there are robust physical arguments as to why ECS > 2K. There are also indications that the cloud feedback is probably positive. There are also reasons to be slightly cautious about some of these Bayesian estimates of climate sensitivity, which we discussed in some more detail in this post (in fact the priors shown in Figure 3 in the paper seem to highlight what we discussed about Nic Lewis’s priors).

However, I do think that this new paper is a nice extension of the work Nic Lewis has done before. What would be nice would be to maybe include more physics so as to exclude regions of parameter space that we regard virtually impossible (for example, ECS values below 1K). My suspicion is that doing so would shift the distribution to slightly higher values and would make the result even more consistent with the IPCC estimates.

Links:
Climate sensitivity reconciled.
Reconciling ECS estimates – again.

Posted in Climate change, Climate sensitivity, Research, Science | Tagged , , , , , , | 133 Comments

Carbon budget constraints

I’d been meaning to highlight a statement from Kevin Anderson for quite some time. A brief lull in postings gives me a chance to do so. It relates to the Paris goal of keeping global warming below 2oC. I haven’t double checked the numbers, but they seem reasonable and I’ve included an animation from Carbon Brief at the end of the post that nicely illustrates how difficult this is becoming.

I’ve highlighted some aspect of Kevin Anderson’s statement that I found particularly important (I transcibed it, so any errors are probably mine).

Once highly optimistic assumptions are made for curtailing deforestation, increasing afforestation and reducing process emissions from industry (primarily cement and steel), the energy-only carbon budget is highly constrained. In the absence of heroic assumptions about negative emissions (increasing the budgets) and ignoring additional positive feedbacks (reducing the budgets), OECD nations need to be fully decarbonised by 2035, with the non-OECD nations following suite in the 2050s.

Transposing this into mitigation rates (dictated by the budgets), requires OECD nations to be delivering 10% annual cuts from about ~2018 onwards. Turning to non-OECD nations, on aggregate they need to reach a peak in emissions by the early 2020s before ramping up to ~10% p.a. by the early 2040s. Add up all of this, and the collective budgets are broadly consistent with a reasonable chance of 2oC.

It is important to note that the nature of the carbon budgets mean that any failure to deliver deep mitigation rates in the near term (from a high starting value) very rapidly increases future rates to completely unattainable levels. Delay is not an option and our 2oC mitigation analysis needs to be informed by this.

We can of course throw our hands in the air and declare the implications of such emission constraints are too onerous for us high-emitters to contemplate. But then we need to be honest and say to our and others’ children, as well as many millions living in poor and climate-vulnerable communities, that we have chosen to renege on the Paris commitments. This is an authentic position, allowing others to consider the implications and make whatever contingencies they can to deal with the chaos of the 3-5oC of warming we’ve decided to bestow upon them.

Carbon brief has a recent article about carbon emissions that is relevant. It includes a figure showing how the emission pathways consistent with a 66% chance of staying below 2oC depend on the year in which emission reductions start (or could have started). An animation of that figure is in the tweet below; it’s clearly getting increasingly difficult.

Posted in Climate change, ethics, Global warming, Policy, Politics | Tagged , , , , | 25 Comments

Climate communicators in Edinburgh

It was a bit of a weekend of climate communication in Edinburgh. Yesterday morning I went along to Dynamic Earth, where the Natural Environment Research Council was hosting an event called UnEarthed. Ed Hawkins was there with a display about their Weather Rescue project.

Yesterday evening I went to go and see Katharine Hayhoe give a talk. It was really very good; informative, entertaining, passionate; everything that you would expect from an excellent science communicator. The focus was the idea that facts aren’t enough, that you need to find innovative ways to engage with people, rather than simply plying them with more and more facts.

The suggestion was that there are a number of steps to effectively engaging with those who might be dismissive of the risks associated with climate change. Try to appreciate other people’s positions and look for shared values, try to find ways to connect, explain what we do, and don’t, know (including that scientists agree), and try to be inspiring.

These all seems like quite reasonable suggestions that are probably more difficult in practice than they are in theory. I would really quite like to be able to better communicate; to be more passionate. However, I think it’s partly not in my nature (this post was probably one of my more passionate ones, and even it doesn’t really qualify), it’s partly been beaten out of me (figuratively, rather than literally), and it’s partly a consequence of scientific reticence. I think scientists sometimes feel that their role is more to inform than to influence, and this does somewhat constrain how they communicate.

We did have a brief discussion at the end of the talk about how science communicators could be more passionate, and how there are some who think that they should remain dispassionate. My own view is that we should be very careful of buying into the Pielke-like attempts to define how scientists should conduct themselves in public. I think scientists are as entitled as anyone to communicate passionately about a topic that they regard as important. On the other hand, I also think that some feel more comfortable aiming to simply provide information that others can use as they see fit

The one concern I have with the “facts aren’t enough” message is that it doesn’t mean that facts aren’t important; even though they may not be enough, we don’t want to discourage those who feel more comfortable presenting facts than trying to find innovative ways to engage. Even those who can find ways to engage effectively with those who have a tendency to be dismissive of the risks associated with climate change still need “facts”.

I must admit that even though I found Katharine Hayhoe’s talk very interesting and thought-provoking, I’m still not sure how I can better engage publicly. Someone did once suggest to me that maybe we should consider leaving science communication to those – like Katharine Hayhoe – who can identify, and engage, with those dismissive of some areas of science. I didn’t really agree then, and I still don’t really agree, but it is something I do consider. What I do think, though, is that we certainly need more people who are able to engage effectively, and passionately, with those who seem reluctant to accept that climate change carries risks that we really should be trying to address.

Posted in Climate change, Science, Scientists, The philosophy of science | Tagged , , , , , | 111 Comments