Quantifying and Thinking About Climate Risk

My friend Mark Boslough presented a fascinating analysis last month at AGU comparing the risks of climate change to big rocks from space hitting Earth:

One objective way to compare the relative magnitude of the impact threat to that of anthropogenic climate change is to estimate the long-term worldwide fatality rate. For asteroids, the average is about a hundred deaths per year–about half of which are climate-change related. By contrast, the World Health Organization (WHO) has estimated that 150,000 deaths per year are currently attributable to anthropogenic climate change.

From the AGU poster:

The risk of global catastrophe is dominated by low-probability, high-consequence occurrences. The asteroid threat community has been much more successful than the climate change community in characterizing the dominant “worst-case” scenarios and communicating them to policy makers, the media, and the public–even though the climate change threat is more than a thousand times greater. Media focus on exceptionally unlikely impact scenarios is common, whereas focus on high-consequence climate scenarios is often unfairly labeled as “alarmist”. Quantitative comparison of climate change to asteroid impact is a valuable way to put both threats into perspective.


  1. I think the conceptualization of how to fight those problems is different enough to warrant the different reactions. Asteroids? What do we do?! And the answer is shoot them. Or build guns, rockets, that sort of thing. Asteroids as a problem are big, but (and please, correct me if I’m wrong here) that problem can be dealt with via explosives. Clear targets, so the problem is making sure we have effective weapons.

    Global Warming isn’t a problem that can be shot.

  2. John,

    an excellent and useful analogy, thanks.


    Actually it’s not just a matter of blowing up the asteroid. If you do that, the mass scatters out, carrying its initial momentum, making a hit perhaps less devastating (leaving aside the fact that the lucky particles are accelerated) but more likely.

    As I understand it, you have to detect the asteroid early, then create a massively expensive mission to mount rockets on the rock to steer it away. Many people will not want to sign the check if that happens. Convincing them
    that such an impact is large enough and likely enough to create a massive mission will be one problem. Allocating who pays will be another.

    The analogy to climate change is then that we already see the asteroid coming. It could be a direct hit or a near miss but it’s looking more like a hit every day. How much should we reasonably be willing to pay to avoid it? And who should pay?

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