Heat waves and climate change

Posted by Tatyana Deryugina on Jul 10, 2012

Filed Under (Environmental Policy)

The recent weather extremes over much of the US have created a flood of articles about the link between these heat waves and climate change. Here is one example. For other examples, just go to Google news and search for “heat wave climate change”. Or you can just keep reading this blog post.

Are these recent events being caused by climate change? The answer is “maybe”. Certainly, climate change is predicted to increase the number of heat waves. But attributing a particular event to climate change is very difficult, even when the event is as extreme as the heat waves of the last two weeks. Of course, if such events are more likely under the “climate change” scenario than under the “no climate change” scenario, we should reasonably think that climate change is more likely than not. But because such heat waves are possible during the “no climate change” scenario as well, we cannot rule out that these temperatures would have occurred even if climate change were not a possibility. So all we can do is make statements like, “There’s an 80% chance that the heat wave was due to climate change, and a 20% chance that it was part of natural fluctuations.” (like this guy).

What should we do in light of this uncertainty? Pay attention to the science and the scientists rather than the weather fluctuations. 97% of scientists agree that climate change is real and caused by humans (see this paper for details). Given the high degree of consensus and the time it takes to for carbon dioxide to dissipate in the atmosphere, we shouldn’t wait until we’re sure that we’re experiencing the predicted effects of climate change firsthand. As evidenced by the deaths and misery in the past weeks (see this article for more), extreme weather still has the power to kill, even in developed nations. Trying to figure out a cost-effective way to address climate change is what we should focus our efforts on (more on that in a later post).

6 Responses to “Heat waves and climate change”

  • Jason says:

    “Of course, if such events are more likely under the “climate change” scenario than under the “no climate change” scenario, we should reasonably think that climate change is more likely than not. ”

    Base rate neglect!!

  • Tatyana Deryugina says:

    Yes, I knew that as I was writing it. I find it hard to be precise, concise, and clear to non-economists at the same time. I went for concise and clear, but maybe I should add a clarifying point :)

  • Ronald Dolgin says:

    It is clear you have confounded “reason” and faith. To take a weather event as “evidence” is faith, and your politics are religion. Thanks for the worship session. The science suggests possible climate change. And in one fatal flaw, the charge to the international science community to establish links and recommendations that were reliably “actionable” was not successful. There are many other actionable areas to prevent deaths and disease, however.

  • Tatyana Deryugina says:

    Thanks for the comment, Ronald. I’m not quite sure what you mean, however. There’s a clear formula for statistical inference called Bayes’ rule (http://en.wikipedia.org/wiki/Bayes'_rule), which I was trying to describe in words. It is objectively the correct formula to use in this situation. And the ultimate point of the post is that we should be paying attention to science, not the weather.

  • Dan says:

    I too wrote a blog last year about the difference between weather and climate, but I really like your description of the probability that a record heat wave is related to climate change.

    Here is a link to that entry:
    http://businesspublicpolicy.com/?p=1833

  • Tatyana Deryugina says:

    Thanks for the link, Dan! I was just arriving at Illinois, so I missed that post. Nice post as well – definitely fancier than mine :)