Free Ride

Planes. Trains. Automobiles. Spacecrafts:

‘We have to inhabit other planets’: Gary Johnson offers libertarian solution to climate change https://t.co/Gz1bdYFDRg pic.twitter.com/8HGQlnN5My

— Raw Story (@RawStory) September 25, 2016

Discuss.

Science is broken!

There’s been quite a lot in the media, and elsewhere, about problems with science. A common theme at the moment is the replication crisis, but you regularly see claims in the blogosphere that papers should be retracted because they supposedly have errors, and I’ve even seen some argue that we should find ways to penalise scientists who misrepresent our current understanding.

I’m a bit tired, and can’t really face writing anything too lengthy (I may fail) so thought I’d make some basics points and let others express their views in the comments. It’s clear that some of the criticisms have merit. We should promote good practice and should encourage people to publish research that is careful and thoroughly checked. What we value (lots of grant funding and papers in Nature, for example) does not always reflect actual quality. We should publish negative and null results and should aim to also publish replication studies. We could improve how we undertake peer-review.

However, science (by which I really mean fundamental research) is about understanding things, typically things we don’t yet understand fully. People should take risks; that’s how we solve interesting problems. People will get things wrong; it’s part of the process. People will try methods that turn out not to be very good; again it’s part of the method. We should encourage people to challenge existing paradigms, even if what they do ends up being horribly wrong – the quality of the challenges can tell us something of how hard it is to overthrow well-established ideas. We should base our understanding – or lack thereof – on an assessment of all the available evidence, not simply on one, or two, studies.

In some sense, that seems to be where some of the problems lie. In normal science, we trust our overall understanding when there is a large collection of consistent evidence. In some cases, however, important decisions are based on one, or a few, studies. When these turn out to be wrong, the impact can be substantial. In my view, however, this is not normal science; we shouldn’t be basing our understanding on only a few studies. Sometimes, it may be unavoidable, but we should still be careful of judging science overall, on the basis of a few examples like this.

Maybe in cases like this (when we do need to make decisions with limited evidence) we should scrutinise the evidence more carefully. In normal science, however, I would still favour trusting the method, rather than encouraging detailed scrutiny of individual studies (nothing wrong if people want to do this, but I don’t see the overall value). That doesn’t mean that there aren’t things that we could do to improve the overall quality of research, just that the problems are not – in my opinion – nearly as great as might be indicated by some of the examples that are often given.

Anyway, that’s a summary of my general views. If anyone else would like to add anything, or make a different argument, feel free to do so through the comments.

The BBC and its balance, again

I had been struggling to find things to write about, but I listened this morning to the Today show on BBC Radio 4. It included an interview with David Hempleman-Adams, expedition leader of the Polar Ocean Challenge, which has successfully transited both the North East and North West passages; circumnavigating the North Pole in a single Arctic summer.

Even though he was clearly concerned about the reduction in Arctic sea ice, and highlighting this was clearly one reason for the expedition, he was also clear that they aren’t scientists and that you can’t infer too much from their expedition. Their intent was really to encourage people to pay more attention to what scientists are saying about the Arctic and, in particular, Arctic sea ice. It was all going well, and then the interviewer said:

… the well-known science writer, Matt Ridley, has written about your expedition and said, look, there are times in the past where, routinely, ice has disappeared during the summer, and his argument is that really, it doesn’t matter, it doesn’t actually tell us anything.

Why Matt Ridley, and why should we care what he thinks? He doesn’t have any expertise that would suggest his view carries more weight than those of anyone else. Also, he may be a well-known science writer, but he’s also a Viscount, a member of the House of Lords, the ex-Chairman of Northern Rock, and Academic Advisor to the Global Warming Policy Foundation, and has coal mines on his land. Referring to his simply as a well-known science writer would seem to be ignoring many other relevant descriptors.

Matt Ridley’s views on Arctic sea ice appears to come from an article he wrote for the Times called an ice-free arctic ocean has happened before. His basic point is that the Arctic has been ice-free in summer before everything was fine. He concludes with

The effect on human welfare, and on animal and plant life, will be small. For all the attention it gets, the reduction in Arctic ice is the most visible, but least harmful, effect of global warming.

Really? No caveats. Absolute certainty. The effect will be small and it will be the least harmful effect of global warming. How can he possibly know this? He can’t even write like a scientist and we’re supposed to take his views seriously?

What about his sources? Well, he provides none for his absolutely certain conclusions, but earlier in his article, he does say

It seems that the quantity of Arctic sea ice varies more than we used to think. We don’t really know how much ice there was in the 1920s and 1930s — satellites only started measuring it in 1979, a relatively cold time in the Arctic — but there is anecdotal evidence of considerable ice retreat in those decades, when temperatures were high in the Arctic.

Where does his anecdotal evidence come from? Why, it comes from Anthony Watts and Steven Goddard, two people who have contributed significantly to the promotion of science denial. I know Matt Ridley objects to being regarded as a science denier, but it is hard to see why; if he really doesn’t like it, maybe he should stop getting his information from sites that are clearly promoting science denial. If you want a more reliable source, you could try this, which says:

The consolidated database shows that there is no precedent as far back as 1850 for the 21st century’s minimum ice extent of sea ice on the pan-Arctic scale.

So, in an interview with someone who undertook an expedition so as to encourage people to listen more to what scientists are saying about the Arctic, the BBC manages to introduce the views of Matt Ridley, an advisor to the Global Warming Policy Foundation and someone who gets their information from sites that promote science denial. Could it have been more ironic?

Weather, or climate change?

I start teaching again tomorrow, so it’s going to be a busy few months and posting will probably be light. I also don’t really have much to say at the moment, but that will probably change🙂. I did, however, want to post this video that I found recently (see below). It discusses the link between weather events and climate change. It includes Kevin Trenberth making the point that the environment in which all events occur is different today, than it was in the past. Consequently, every event is different.

What I particularly like about the video is that those being interviewed regularly refer back to basic physics; evaporation, energy, increasing water vapour in the atmosphere, etc. We do have a very good understanding of the basic physics associated with climate change. Just because we have not definitely found some signal in a dataset, does not suddenly bring this understanding into question. Of course, if we would expect to have seen a signal, and do not, it might. Not seeing something in incomplete, or noisy, data does not.

Of course, there are certain aspects that are complicated and where the impact of climate change may not be obvious. There are others, however, where it would be extremely surprising if climate change did not increase the frequency and intensity of the most extreme events; as Kevin Trenberth says “at the high [is] when you start breaking records”. Maybe I’m biased, but I think it’s important to realise that our basic understanding of the underlying physics is very strong and that gives us a very good understanding of what – in general – we might expect. I’ll leave it there, and I recommend watching the video.

Engineering the software for understanding climate change

Since Judith Curry has a guest post about global climate models and the laws of physics, I thought it would be worth posting this recently released video of a talk about climate modelling (see below). It’s by Steve Easterbrook, who is a Professor in the Department of Computer Science at the University of Toronto.

One problem with blogosphere critiques of climate models is that it often seems to come from those who might have some relevant expertise, but who have never actually run a climate model, or spent any significant amount of time talking with those who have. They also seem to base their critique on things they’ve read on the internet and – as a result – assume climate modellers do not understand some pretty fundamental things; ignoring that online material about climate models, aimed at the general public, will clearly not include the kind of details that you will find in the scientific literature. Additionally, they assume that climate modelling should be conducted in a manner similar to what they themselves might have experienced, ignoring that what might work in one field, might not in another.

What Steve Easterbrook did was spend a lot of time at the UK’s Met Office, interacting with – and learning from – those who do run, and develop, climate models. He found that there are reasons why climate modellers might behave differently to software engineers, or those doing computational modelling in industry. Climate models are scientific instruments. The goal is not to design a new climate, or produce some specific product; the goal is to understand our climate, and how it might respond to changes. He also discussed how they continually test the models and how there are very few defects, per thousand lines of code. His argument for this being that in such a code, it can be fairly obvious when there is a problem, and therefore you can find, and fix, defects more easily than might be the case in other codes.

I don’t think I need to say much more. The talk is a little long, but it’s certainly worth watching. Steve Easterbrook’s blog is also very good, and has a number of posts about climate models.

References:
The talk is – I think – from 2011, but has only just been released. As Victor Venema points in the comments on youtube, the paper on which it is based is here.

Why I find it difficult to discuss climate policy

I generally try to avoid discussing climate policy specifically. One obvious reason is that I don’t have any particular expertise in that area, or any special insights. However, there is a somewhat subtler reason as to why I find it a difficult topic. When I read something like this post about carbon taxes (which I discussed here) it makes a lot of sense. There are lots of factors to consider. If we do too much now, the current generation could pay much more than their fair share, and we could do more harm than good. If we do too little now, we could pass on too much to future generations. It’s a difficult balancing act.

Then I start to think a bit more like a physicist. Our climate is a complex, non-linear system. We have the potential to change it substantially, and to do so very quickly. We could change our climate by an amount comparable to the change between a glacial and an inter-glacial, but could do so ten times faster than has occured in the past. For small changes, we expect the response to be linear, and maybe it will remain linear even if we induce what is quite a large change. On the other hand, maybe not; it’s not impossible that it could flip into some kind of new state. Maybe such a new state would be beneficial. However, I would guess that the region of parameter space in which changes would be beneficial is dwarfed by the region of parameter space in which it would be very detrimental.

On top of being a physicist, I’m also involved with finding planets around other stars. This makes me very aware of the fact that the only place in the universe where we know life to exist is on our own planet. In fact, the only place is in a very thin shell around our planet. What makes this planet habitable is our atmosphere, into which we’re currently dumping CO₂ like there’s no tomorrow. Even if there is life elsewhere – as there probably is – it also doesn’t really make any difference; this is our home for the foreseeable future. Treating our atmosphere like a waste dump, seems like a really bad idea.

So, of course I think that dumping giga-tonnes of CO₂ into our atmosphere and pushing our climate hard and fast is something we should probably avoid doing, but how? I just end up back at the beginning again; just because we should probably not be dumping giga-tonnes of CO₂ into the atmosphere doesn’t mean that it’s easy to work out how best to not do so. There are clearly many factors to consider. However, ignoring – or even dismissing – that what we’re doing carries risks and is probably unprecedented, doesn’t appear to be an effective way of encouraging that we take this seriously and actually start doing something substantive. It’s why I find myself getting frustrated by some of the social science comments on this topic; they seem to often ignore what makes this an issue worth taking seriously.

Anyway, I’m not really sure where I’m going with this. I guess it’s that climate policy (by which I mean what we should decide to do) is a very difficult and complicated issue. On the other hand, deciding whether or not we should actually do something, doesn’t seem all that complicated; to me, at least.

The attribution question

It seems as though the issue of trying to attribute an anthropogenic influence to an extreme weather event is controversial on a number of levels. It sometimes seems to divide even those who largely agree, and almost always produces a push-back from those who appear to want to dismiss the risks associated with climate change. Some of this push-back is justified, but some is no better than those who make overly strong claims about an association between climate change and an extreme weather event. Not being able to make some kind of formal attribution does not mean that there is no link between climate change and these extreme events.

My own view is that asking whether or not climate change caused a particular extreme event is silly; we can’t answer that question. What we can do, though, is consider how anthropogenically-driven climate change has influenced the likelihood of certain events. Naively one might argue that in a warmer world we would expect, for example, an increase in the frequency and intensity of heatwaves and extreme precipitation events. This may be reasonable globally, but as this paper by Friederike Otto and colleagues points out, regionally it depends on both thermodynamic changes (more energy) and changes in atmospheric circulation.

To try and understand how climate change is likely to influence extreme events – regionally at least – one therefore needs to consider both warming (thermodynamics) and how it influences the movement of atmospheric patterns (circulation). Circulation changes could reduce the likelihood of some events in some regions, while enhancing it in others. The key point, though, is that this is not an attempt to determine if climate change is causing these extreme events; it is simply trying to establish how climate change influences the overall risk of these extreme event.

I may not have explained this properly, but fortunately the author is on hand to do a better job than I can.