The adults in the room

I was having another discussion on Twitter with Jean Goodwin, who posted the following quote. It’s attributed to Mark Largent and may have been delivered at a AAAS meeting.

I’m interested in what other people think of this. I don’t know, however, the context, or if this quote properly represents what was trying to be presented. If it does, though, my initial reaction is to be quite irritated. Broadly speaking, I don’t see how this relates to reality. Scientists don’t have control over what we already know; the work has been done and the information is in the public domain. Also, the benefits of this knowledge have not simply gone to scientists; society as a whole has mostly benefited from our improving understanding of how the world works. Of course, there are aspects that may not be positive (the ability to destroy ourselves) but the positives, in my view, outweight the negatives.

What about this authority and power? I don’t see scientists as having any special authority and power. Scientific/technological knowledge can be powerful, but this is not restricted simply to people who are identified as scientists. Maybe we could restrict how much information/knowledge is released into the public domain, but most who identify as scientists don’t work in an environment where this is the norm, or even really possible.

A few other thoughts. Who is being referred to as “scientists”? Is it simply physical scientists, or is it all scientists (physical, natural, social). If the latter, then why use the term you guys, rather than simply we; it is being presented by a social scientist. The use of you guys also seems unfortunate. I realise that it can sometimes simply mean people, but it is often taken to refer to men specifically. We should, ideally, be avoiding such steoreotypes.

To be clear, my issue is not with the idea that scientists should be adults in the room; ideally we should all strive for this. My issue is with the idea that we’re in some kind of special position in which we simply have to accept the harassment because of our perceived power and authority, and with the implication that we have to be the adults in the room because others won’t be. A sense I have is that we have to excuse politicians, or the media, or business leaders, because that’s just how they are, but we can pressurize scientists to behave in some ideal way. Why can’t we expect these ideals of all, rather than only of scientists? If power and authority require that some group become the adults in the room, I would argue that there are many groups ahead of scientists.

As usual I’ve written more than I intended. I realise that I have a bit of a knee-jerk reaction to things like this, because I just find this targetting of scientists annoying. Maybe I’m missing something about this, and maybe there is more merit to it than I appreciate. If so, feel free to try and convince me.

Posted in ethics, Science, Scientists, The philosophy of science, The scientific method | Tagged , , , , | 178 Comments

Sea level rise

There’s a bizarre article in the Wall Street Journal by Fred Singer called, The Sea Is Rising, but Not Because of Climate Change. It’s actually so bonkers that it’s quite hard to know where to start. I’ll give it go, though.

It says

It is generally thought that sea-level rise accelerates mainly by thermal expansion of sea water, the so-called steric component.

I note particularly that sea-level rise is not affected by the warming; it continues at the same rate, 1.8 millimeters a year, according to a 1990 review by Andrew S. Trupin and John Wahr. I therefore conclude—contrary to the general wisdom—that the temperature of sea water has no direct effect on sea-level rise. That means neither does the atmospheric content of carbon dioxide.

The steric component of sea level rise is due to the thermal expansion of sea water. The rate at which it rises depends on the rate at which energy is being added. It doesn’t have to be accelerating for the rise to be due to thermal expansion.

However, current sea level rise is not only due to thermal expansion. As the figure on the right shows, sea level is rising due to a combination of thermal expansion, ice loss from Greenland, Antarctica, glaciers and due to terrestrial water storage (TWS).

A key point is that the oceans have, by far, the largest heat capacity of the climate system. Sea level is a very strong indicator that the climate system is accruing energy. The only way this can happen is that there is more energy coming into the system, than going out, and the reason this is happening is because we are dumping CO2, and other greenhouse gases, into the atmosphere, which reduces the outgoing long-wavelength energy flux.

Credit: Hansen et al. (2016)

The article by Fred Singer then appears to completely contradict itself. After suggesting that sea level rise is not accelerating, he goes on to say

But there is also good data showing sea levels are in fact rising at an accelerating rate.

Well, yes, as the figure on the left (from Hansen et al. (2016)), shows sea level rise is indeed accelerating.

So, sea level is rising and its accelerating, and this is almost entirely due to anthropogenic influences. This is primarily our emission of greenhouse gases into the atmosphere, which is producing a planetary energy imbalance that is resulting in the accrual of energy in the climate system. This leads to both thermal expansion of the ocean and the melting of land ice. It can’t really be anything else.

Posted in Climate change, ClimateBall, Comedy, Global warming, Pseudoscience | Tagged , , , , | 210 Comments

Carbon budgets and the impacts of climate change

I’m somewhat stealing this from Stoat, but it’s an interesting topic, and it really originates from a tweet by Gavin Schmidt anyway 😉

In retrospect, this seems obvious, but I don’t think I’ve seen this explictly pointed out. The basic point is that a carbon budget tells you how much we can emit if we want some chance of keeping warming below some level and, consequently, avoiding the impacts of warming beyond that level. The Social Cost of Carbon (SCC) is an estimate of the future cost of emitting CO2 into the atmosphere, typically discounted to today. The SCC can then be used as a carbon tax, so that we then pay the full price of emitting CO2 into the atmosphere.

In some sense, they don’t even really seem like comparable concepts. A carbon budget is simply some information (how much can we emit to have some chance of keeping warming below some level). It doesn’t provide any information as to how to do so. A carbon tax, on the other hand, is actually a policy instrument; if properly calculated, it would mean that we were paying the full price of CO2 emissions and the market could then respond in some optimal way.

A couple of recent papers have argued against carbon budgets, but I still quite like the basic concept. It tells us, quite simply, how much we can still emit to have some chance of not warming above some level. There, are, however some obvious problems. How do we define the level? How do you partion the budget and how do you decide when to start and how fast to reduce emissions? What do you actually do to meet the budget?

A carbon tax, on the other hand, is simply something you add to the cost of energy based on how much CO2 is emitted into the atmosphere. The market can then respond accordingly. If fossil fuels (with emissions into the atmosphere) were still the cheapest way to generate energy, we’d carry on doing so. If there were alternatives that were cheaper, we’d presumably switch. There would be no specifically trying to pick winners and losers; the market would, ideally, evolve in the most efficient way that it could. A key point, though, is that a carbon tax is not based on a carbon budget; it is simply based on the future cost of emitting CO2 into the atmosphere.

So, even though I like the idea a carbon budget because of the basic information it provides, I don’t see how this information actually generates any action. A carbon tax, on the other hand, would actually influence emissions and, ideally, in some optimal way.

I should, of course, acknowledge that I’m simply a physical scientist, so may have not have explained some of the above properly. Happy to be corrected if I have blundered in some way. However, to potentially generate some discussion, and to possibly illustrate my ignorance, there is one aspect of a carbon tax that has always bothered me.

A carbon tax is not paying to avoid some future damage, it is actually paying for the future damage (discounted to today). In terms of the global economy, simply applying a carbon tax might still be the optimal way to influence future emissions. The problem, though, is that someone will eventually pay for the damages. In principle, the global economy will have grown in the most optimal way and so those in future will be best placed to cover these costs. In reality, however, there is no guarantee that those who pay the costs will have benefitted from this growth. In principle, wealthy parts of the world could simply decide to pay now for damages that will, in future, impact parts of the world that are far less wealthy and that have not benefitted in a way that makes covering these costs viable.

To be clear, maybe I’m wrong about the above and there is some subtlety that I’m missing. If so, would be keen to better understand this. On the other hand, maybe I’m right but there is still not a better alternative. Thoughts?


Why are carbon taxes so low? (Post of mine discussing a Joseph Heath post on carbon taxes.)
Politically informed advice for climate action. (Nature paper by Oliver Geden.)
Beyond carbon budgets. (Nature paper by Glen Peters.)

Posted in Carbon tax, Climate change, Gavin Schmidt, Policy | Tagged , , , , | 81 Comments

Dark webs

I’ve been trying to think of what to say about this New York Times articles discussing an alliance of heretics, and I’ve been struggling. I think it’s important to have people who challenge the orthodoxy, and who express views that are typically regarded as controversial, but the whole article about them just seems silly. They’re academic renegades, iconoclastic thinkers, who are the vanguard of this new intellectual dark web, all accompanied by rather odd, darkly lit pictures of these mavericks.

I guess I’m just struggling to see what all the fuss is about. A group of people with quite substantial platforms get to say controversial things. They don’t always get taken seriously, and sometimes they get quite strongly criticised. Sometimes the criticism is justified, sometimes it isn’t. Similarly, some of what they say is worth considering, some of it is not (quite a lot, in my view).

If what they were saying was widely accepted and rarely criticised, then it wouldn’t really be controversial and wouldn’t really be challenging societal norms. Surely this is all part of the process? If you really want to change how society thinks about things, it’s going to take some time, and it’s not going to be easy. Also, just because some people say things that others might not say, doesn’t suddenly make them mavericks. They could simply be wrong.

I think one of the issues I have with this whole scenario is that it seems that most who are elevated to the status of public intellectual eventually end up saying silly things about something they don’t understand very well. Some may learn from these blunders, but others seem to simply carry on, and then find reasons to criticise their critics.

My preference would be that people who regarded themselves as public intellectuals were more careful about what they say, that their critics were careful to engage with what they actually said, and that the media tried not to elevate individuals to a status that they can never really attain. Of course, this ideal can probably never really be achieved, and so the whole intellectual dark web scenario just seems like a natural consequence of the rather messy environment in which this is all taking place.

Posted in ethics, Open Thread, Philosophy for Bloggers, Politics | Tagged , , , , , , | 593 Comments


There’s been a lengthy discussion on Twitter about RCP8.5. I think it was initiated by Roger Pielke Jr, who continues in his campaign to police the scientific community:

This complaint was then promoted by Matt Ridley, and the discussion ensued. It remained mostly quite pleasant, but I found it quite remarkable that people who have publicly discussed this topic for a good number of years, are still remarkably confused about something that is ultimately quite simple.

The criticism of RCP8.5 was a combination of it being completely unrealistic, and it being a scenario that climate scientists use in their studies so as to get more interesting results. In case some don’t know, RCP8.5 is one of the Representative Concentration Pathways (RCPs). These are a set of scenarios that consider different possible future atmospheric greenhouse gas (and aerosol) concentration pathways. They can also be regarded as possible future forcing pathways; pathways that produce a range of different externally-driven radiative perturbations. They go from one in which we keep the concentrations, and resulting change in forcing, quite low (RCP2.6) to one (RCP8.5) in which the concentrations keep rising, eventually reaching a level such that the change in forcing, by 2100, is 8.5 Wm-2.

These concentration (or forcing) pathways can then be used as input to climate models to try to understand how our climate will respond to a range of different possible future pathways. However, to relate these concentration pathways to our actions requires associating them with emission pathways. However, given uncertainties in the response of the natural carbon sinks, there isn’t a single emission pathway for a given concentration pathway. Even though it would now seem unlikely that we will follow an emission pathway typically associated with RCP8.5, uncertainties in carbon cycle feedbacks mean that we can’t rule out that an emission pathway typically associated with a lower RCP could lead to us following a concentration pathway close to RCP8.5. Therefore, I don’t think we can yet definitively rule out RCP8.5.

The other issue is climate scientists supposedly using RCP8.5 in order to get more interesting results (what Roger calls climate porn). It may well be that climate scientists use RCP8.5 more often than other concentration pathways. One reason for using RCP8.5 is that a pathway with a large change in forcing allows one to better distinguish between the signal (i.e., the response to the change in external forcing) and the noise (the natural variations). One can then probably still use this to estimate what would happen were the change in forcing to be lower [Edit: As Katharine Hayhoe pointed out, you can do this because a high forcing pathway will move through the levels of change associated with the lower forcing pathways]. Another reason will also be that understanding extreme outcomes can, in some cases, be somewhat more important than studying outcomes that we would probably expect to not be particularly extreme.

Of course, I do think that people should be very clear about what they’re doing. It does seem unlikely that will now follow an emission pathway that will lead to an RCP8.5-like concentration/forcing pathway. Therefore people should not present results of studies that use RCP8.5 as being somehow likely. However, this does not mean that there is no value in still considering this pathway. As already mentioned, using a pathway with a large change in forcing can help to distinguish between the forced response, and internal variability. Additionally, there is also a chance that the more we dismiss the possibility of following an RCP8.5-like pathway, the more likely it becomes that we might actually follow one.

H/T: Marcus N Hofer

As pointed out on Twitter (H/T Ambarish Karmalkar) many studies actually use RCP4.5 and RCP8.5. In fact, when I did a quick search, a lot of the results did use both RCP4.5 and RCP8.5. The figure on Roger’s tweet also seems to show this; the two most commonly used scenarios are RCP4.5 and RCP8.5 (with RCP8.5 appearing to be used slightly more often than RCP4.5).

Posted in Climate change, Climate sensitivity, ClimateBall, Policy, Research, Scientists | Tagged , , , , | 270 Comments

It’s mostly about risk

I wanted to post this video (see end of post), that I first came across in this comment (H/T Pehr Björnbom). It’s a few years old, so some things may have changed, but it’s still mostly relevent.

It’s a discussion between Kerry Emanuel (Professor of Atmospheric Science at MIT) and John Christy (Distinguished Professor of Atmospheric Science at the University of Alabama, Huntsville), moderated by Russ Roberts.

John Christy promoted a great many of what I would normally call “skeptic” themes. Fossil fuels are, and will continue to be, the most reliable and economically viable energy source, climate has always changed and there is nothing special about today’s changes, models have projected much more warming than has been observed, and we can’t tell how much of the recently observed warming is natural, and how much is anthropogenic.

Without a carbon tax, his first point may well end up being right. However, the same can’t be said for the rest of what he promoted. The climate has indeed always changed, but studying these past changes has played a key role in understanding what’s causing it to change today (mostly us). When comparisons are done carefully, models actually compare well with observations (should also be careful to ensure that the comparison is really like-for-like). We actually can disentangle how much of the observed warming is natural, and how much is anthropogenic. The best estimate is that we’re responsible for slightly more than all of it.

Kerry Emanuel highlighted that the basics have been well understand since the 19th century, and that a key thing is that this is mostly about risk. We are taking a risk with our climate by emitting CO2 into the atmosphere; doing so will change our climate, these changes could be substantial and the impacts of these changes could be severe, potentially catastrophic. Of course, there are also risks associated with what we might do to address this. Hence, this is not simple and we should think about this rationally.

What I found quite interesting was how Kerry Emanuel approached the discussion. It was very measured and thoughtful and he regularly broadly agreed with what John Christy was saying. Observations are not perfect, climate models do have problems, there is a lot of uncertainty, etc. However, he kept going back to the basics and highlighted that even though we can’t be certain as to what will happen, we are still taking a risk.

I partly thought that this was quite good as it came across well, but I wondered how it would be perceived by a more neutral observer, or by those who are already doubtful. It’s possible that they would walk away thinking that the doubts are quite justified and that maybe there isn’t really any reason to do anything just yet. On the other hand, I don’t really know how else to approach this kind of discussion. Being more confrontational may well come across poorly and be ineffective. I think it mostly highlights how difficult these kind of discussions can be. Anwyay, I’ve said more than enough. Video below.

Posted in Climate change, ClimateBall, ethics, Global warming, Policy, Roy Spencer | Tagged , , , , , | 147 Comments

Speaking out

There’s a current Twitter hashtag called #WeNeedToChangeTheWorld, which WMC has also discussed in this post. It’s bit cliché, but it’s probably true, for many reasons. As also mentioned in WMC’s post, Peter Jacobs tweeted the following

This is similar to what I’ve said before. If a scientist is considering speaking out about something, but is worried about being criticised for engaging in advocacy, maybe they should also consider the regret they may feel in future if they choose not to speak out. This seems pretty obvious, to me. There are pros and cons to everything. There may well be good reasons why some might choose to not speak out, and reasons why others may speak out despite potential criticism.

Also, choosing to do nothing is not necessarily neutral. The status quo is still a political position, and not speaking out may well become deserving of criticism. I’m not suggesting that not speaking out immediately implies endorsing the status quo. It’s possible to not speak out, but to be supportive of those who do. It’s, of course, also possible to have no public profile whatsoever. However, I do think it is hard to have some kind of public profile in which one’s choices do not indicate some kind of preference.

Utimately, I think people need to decide for themselves what they regard as the appropriate thing to do, or not do. Ideally, those who do speak out should be clear about the role they’re taking, should not take advantage of their position when doing so, should provide suitable caveats, should engage responsibly and honestly, should take into account other issues and factors, and should be clear to distinguish between when they’re speaking as an expert with domain knowledge, and when they’re speaking as a citizen with political views.

However, this should really apply to all, so I’m not quite clear as to why there seems to be this focus on advocacy by scientists. I don’t think scientists have a special position either way; I don’t regard them as being a group who should specifically avoid advocating, or a group whose advocacy should be taken more seriously than that by others.

I think some regard advocacy by scientists as violating a fundamental tenet of the scientific process – objectivity. I simply don’t agree with that. Scientists should aim to be objective when carrying out their research, but doing so doesn’t remove their rights to engage in broader society. I get the sense that some regard scientists as having too much influence. This may be true, but I think this should be resolved by others speaking out more convincingly, rather than by scientists speaking out less.

Utimately, I think people should simply decide what they think is right and best for them, and act accordingly. I do, however, think that people should consider that there are potential consequences to what they might do, or not do. I’m also not suggesting that scientists who do choose to advocate should not be criticised. They’re as open to criticism as anyone who chooses to speak publicly. Ideally, they should be critiqued on the basis of what they say, rather than who they are. Of course, speaking out is inherently political, so expecting the criticism to be ideal is probably unrealistic.

Posted in ClimateBall, ethics, Policy, Politics, Scientists | Tagged , , , , | 144 Comments