About Rationally Speaking

Rationally Speaking is a blog maintained by Prof. Massimo Pigliucci, a philosopher at the City University of New York. The blog reflects the Enlightenment figure Marquis de Condorcet's idea of what a public intellectual (yes, we know, that's such a bad word) ought to be: someone who devotes himself to "the tracking down of prejudices in the hiding places where priests, the schools, the government, and all long-established institutions had gathered and protected them." You're welcome. Please notice that the contents of this blog can be reprinted under the standard Creative Commons license.

Monday, September 30, 2013

Rationally Speaking podcast: Michael Mann On The Science Of Climate Change

In this episode of Rationally Speaking, Julia and Massimo talk to physicist and climatologist Michael Mann about how we know the climate is getting warmer. Among other things, they cover the physical processes of climate change, the role that predictive models have played in confirming scientists' theories about the rate of warming, and what are uncertainties in the science. Also, how optimistic we should be about technological solutions to the problem.

Dr. Michael E. Mann is Distinguished Professor of Meteorology at Penn State University, with joint appointments in the Department of Geosciences and the Earth and Environmental Systems Institute. He is also director of the Penn State Earth System Science Center. Dr. Mann is author of more than 160 peer-reviewed and edited publications, and has published two books including Dire Predictions: "Understanding Global Warming" in 2008 and "The Hockey Stick and the Climate Wars: Dispatches from the Front Lines" in 2012. He is also a co-founder and avid contributor to the award-winning science website RealClimate.org.

Michael's pick: skepticalscience.com


  1. Great interview. But I have a comment.

    I feel there needs to be more skepticism injected into the climate change problem. There is an intelligent skeptical response to climate policy (and policy issues are an often implicit but ever-present component of climate science) that does not require questioning the current science of climate change. Consider the following:

    A. Probability that it is happening and is anthropogenic (according to the recent IPCC report, 0.95)

    B. Probability that it would have serious deliterious consequences that wouldn't have happend otherwise (unknown and loosely defined, but let's say 0.90)

    C. Probability that future mitigation will fail (also unknown, let's say 0.8)

    For climate change to justify a particular policy response (say, carbon tax), the product of A,B and C has to be high. Is 0.68 high? I guess high-ish. But I think the latter two probabilities could easily be overestimated here. If they were a little lower, the product of these probabilities drops. For example, an optimist might say there is a better than 50% chance that carbon sequestration technologies will work well in 20 years. If we make the 3rd term 0.5 then the product of A,B anc C is 0.43. Is this high enough to abandon all skeptical resistance to policy responses on climate change? Meh...

    Maybe the precautionary principle would still guide our hand because of the chance (even if it were small) of catastrophic disaster (avoiding the 'fragilities', as Nassim Taleb would put it). But this is precarious reasoning (lots of thoughtful work on this...). Furthermore, none of this takes into account the opportunity costs of 'doing something'; the resources spent on mitigation could be spent on something else that could be more immediately beneficial.

    In short, Massimo, I think you are right to keep your apartment...

    1. niwiyi,

      well, we can have a discussion about your estimated probabilities and risk scenarios (with which I disagree), but at least that would move the debate forward: from questioning the existence of anthropogenic climate change (which, at this point, is pretty silly) to what to do about it.

      But in the latter case I'm not sure why one would need to use the word "skeptic" at all. All sorts of possible policies should be on the table for discussion, with the decision making dependent on scientific, economic and social considerations.

    2. So lets do! What are you doing about it Massimo, I think the solution is not up to the governments but rather up to you and me. What can or should we do? =

  2. You aren't sure about the need of the word skeptic? Really? Bad policies abound (just one example, green energy subsidies in Western Europe and some parts of Canada) largely because of a blind and uncritical embracing of green policy. I think environmental policy desperately needs some truly skeptical (yet well meaning and human-centred) voices.

    Perhaps you can be more specific about the risk scenarios and probabilities you disagree with, but in any case, I gather that you do not disagree with the general problem of error propagation (which is what my example highlights)?

    1. I like to reserve the word "skepticism" for a limited range of applications. What you are referring to are standard discussions about policy, where all alternatives are reasonable or at least not wacko. Unlike the outright denial of climate change.

      Incidentally, of what "environmental policy" are you speaking of? The US, at the moment, simply doesn't have one, in large part because Republican wackos still insist that there is no problem to begin with.

    2. Fair enough; I will take more care in the use of the word skepticism in the future. However, I think the demarcation between climate science and climate policy is often unclear, and further, that climate scientists too easily drift into policy questions and questions of human impact--as Mann did in this interview. I only meant skepticism in the sense of holding good scientists' feet to the fire a little more.

      I am not American, and do not live in the U.S., so that's not my reference point, but there are some state policies--such as carbon offsets in California. Furthermore, U.S. federal energy policy decisions (such as on the Keystone pipeline) are enormously important, but are often not well informed about the most basic science on the ground partly because of blind ideology--on both ends of the spectrum. I raise Keystone because it is a particularly good example (for reasons I can, but won't, elaborate on).

      As a final bit of context, every year I ask 4th year undergrads in environmental science whether or not it is OK to lie about the science in order to galvanize public opinion behind and environmental cause. The vast majority say yes. That makes me angry, and I blame Al Gore :)

  3. May I ask, since the climate changes all the time, and knowing what we do about predictability of future state in non-linear, complex systems; and since anything that is science must be testable, what would the climate look like without anthropogenic climate change?

  4. Are you saying that C02 alone can cause harmful "climate change" without an intermediate step of warming? there has been no warming in the last 200 months. You use cars, heat your home, use electricity, use energy, eat food, produce C02 like other Americans. What do you want others to do that you are not doing? Don't be a hypocrite. I think your politics overrides your skepticism. A true skeptic recognizes AGW for what it really is, a money grab.

  5. Of course we're all complicit. A better question might be, which big energy companies are the most advanced in moving away from fossil fuels? SAren't they the ones who will lead change? It will happen when it becomes profitable, yes?


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