Will the Icelandic Volcano Cool off the Planet?

As you’ve probably heard, a volcano in southern Iceland known as Eyjafjöll (or Eyjafjallajökull) has recently erupted, its first known eruption since 1823. (Here’s a look via webcam.) It has produced serious local flooding, but that’s not why it has made international news: westerly winds have spread the volcano’s ash plume across much of Europe, grounding thousands of airline flights and causing general distress and wonderment.

DESCRIPTIONPhoto: Reuters Volcanic ash plume at Eyjafjöll glacier, April 14, 2010.

This has led several readers to send us e-mails asking if this eruption might cool the planet a bit. As we wrote in SuperFreakonomics, the gigantic eruption of Mount Pinatubo in the Philippines in 1991 sent so much sulfuric ash into the stratosphere that it reflected enough sunlight to cool global ground temperatures by about 1 degree Fahrenheit for the next two years. Other volcanoes further back in history have had even more drastic climate effects. That’s what inspired some scientists, including Nathan Myhrvold, to suggest that if global warming gets out of hand, one solution might be to intentionally distribute sulfur dioxide or some other reflecting material in the stratosphere, mimicking the cooling effect of volcanic eruptions.

The National Oceanic and Atmospheric Administration recently announced that this past March saw the warmest combined global land and ocean surface temperatures on record. “Additionally,” according to NOAA, “the planet has seen the fourth warmest January-March period on record.”

So has Eyjafjöll erupted just in time to cool things off?

At this point, the answer seems to be a firm no.

As disruptive as Eyjafjöll has been to air travel, it just isn’t that big of an eruption. “There will be some effect, but it would be small, and likely confined to northern Europe,” Myhrvold wrote in an e-mail message. “I don’t think that much has reached the stratosphere. However, in the past the volcano that is erupting was a precursor to another larger eruption, and if that happens then we may see some climate effect.”

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  1. truthseeker says:

    This post appears to be at odds with your book. There, you claim that “Then there’s this little-discussed fact about global warming: While the drumbeat of doom has grown louder over the past several years, the average global temperature during that time has in fact decreased.”

    Yet your co-author put it differently, according to the AP: “Levitt, a University of Chicago economist, said he does not believe there is a cooling trend.”

    and the NOAA data you report in this blog post suggests that your published claim is, to be most charitable, inadvertently misleading.

    Please tell us, what do YOU think is happening to global temperatures? Do you disagree with the NOAA? Will you be issuing a correction or clarification, like Steve did?

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  2. Michael says:

    “Will the Icelandic Volcano Cool off the Planet?”

    Even if it did, global warming would still be happening; it would just be temporarily masked. Just like all other geoengineering solutions. As long as carbon dioxide is being pumped into the atmosphere, more and more geoengineering would be required to keep temperatures from rising.

    What are the economics of trying to stay ahead of an ever-increasing trend?

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  3. cd says:

    Isn’t it postulated that dinosaurs were exterminated by a similar disturbance over a long period of time? Could this be similar to earth being hit by an asteroid? Too bad we don’t plan for these things before they happen. Good luck.

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  4. John says:

    Keep in mind that the reason the planes are grounded is not because the ash blocks the view, but because it might hurt the engines

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  5. Brett says:


    Anthropogenic Global Warming is at this point still a theory and the effects of carbon dioxide increases on the (admittedly small) scale are as of yet undetermined.

    If AGW were fact, no one would talk about it as needing a ‘consensus’ among leading scientists. There is no consensus about gravity, it’s proven fact. There is no consensus about the speed of light, it’s a proven fact. However, AGW is constantly referred to as having a consensus, because it’s still a theory.

    For interesting theories that were widely believed, but eventually proven wrong, check out this site. http://www.toptenz.net/top-10-most-famous-scientific-theories-that-turned-out-to-be-wrong.php

    In the meantime, try not to push your green zealotry on the rest of us.

    What are the economics of trying to stay ahead of a possibly imagined/faked/misunderstood/incomplete trend?

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  6. plive says:

    I was one of those readers that e-mailed you. Thanks for the honest answer. That’s what riveted me to your books and why I required my teenagers to read them. Information seems to slant to one agenda or another these days. Refreshing to get just the plain facts. It is exhilarating to discipline my heart and mind to conform to the facts. Spin is deadly boring – and makes the mind flabby. Nice to find two honest dudes – keep the fun coming!

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  7. Eric M. Jones says:

    Eyjafjallajökull will certainly cool the atmosphere. How much depends….If Laki decides to erupt, you’ll need Depends…. The last time it killed 25% of the population.

    If you REALLY want to see a frightening volcano, check out the Volcano Lightning: Google “volcano lightning”.

    (repost) The main eruptions of Pinatubo occurred in only about 24 hours. During this time it ejected gas, aerosols, and lavas at a rate of about one-million tonnes per second.

    Then again in theory, volcanoes can erupt so much that they can invert the mantle. This may already have happened on Venus.


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  8. Prof. William White, Cornell Univ. says:

    Its not strictly a matter of the size of the eruption, but whether the eruptive column reaches the stratosphere or not (Pinatubo did). Once SO2 reaches the stratosphere, it can stay there for years (because there is no weather to wash it out), effectively dimming the Sun. SO2 in the troposphere will wash out quickly, and therefore will probably not have a prolonged cooling effect. This eruptive cloud apparently does not rise above 24,000 feet and should not have global climatic effects.

    By the way, Brett, science deals only with observations and theories, not facts. Scientifically speaking, gravity and the constancy of the speed of light are, in fact, just theories. Indeed, it has not yet been possible to incorporate gravity into the general theory that explains nature’s other forces. The theory of global warming is based on very well established observations, and is perhaps better understood than gravity.

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