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.”


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?


"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?


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.


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



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?


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!

Eric M. Jones

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.


Prof. William White, Cornell Univ.

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.




I respectfully suggest you learn a bit more about facts and theories. That gravity exists is a fact. It's cause is on the cutting edge of research in physics. As of now, there are many theories to explain it, none has a consensus. The speed of light is much the same. It's speed (in a vacuum) is a fact, why it is, and how scientists are challenging that constant is also an interesting research topic.
I'd submit GW is much the same. We are nearing the point that we can say factually that Earth's temperature is rising. There are a few credible theories to explain this, including anthropogenic causes. I favor increasing research, the price of being wrong is simply too high.


Sean Samis


Talking about a consensus has nothing to do with whether global warming is a fact; it has to do with whether we are sure it's a fact or not. Things don't become facts only when you know for sure they exist. Many people are killed by things they don't know about (or ignore) until it's too late.

A theory is (in this context) an explanation for observed facts. Certainly there are plenty of theories that have been wrong, there are always more ways to be wrong than right. Again, this is irrelevant to the question of whether global warming is real or not. Many theories have been thought wrong, and turned out to be right.

"What are the economics of trying to stay ahead of a possibly imagined/faked/misunderstood/incomplete trend?" What are the economics of waiting until it's too late?

@Eric M. Jones

"volcanoes can erupt so much that they can invert the mantle. This may already have happened on Venus."

I believe the peculiar geological history of Venus is attributed to the near absence of water; water serves as a tectonic lubricant (among other things) so tectonic activity on Venus seemed to have frozen until the underlying mantle got so hot it melted the entire crust. Given our abundance of water, that scenario is unlikely on earth.




"Gravity" is not a "fact" , that is why it referred to as Theory of Gravity or Gravitational Theory.
A theory is a well-substantiated explanation of data.
It is possible that Graviational Theory could be proven wrong some day.

So to use your own semantics that Global Warming is still just a theory you put it into the same realm as Gravity.

I believe the actual word you are looking for is "HYPOTHESIS".


@my responders

I understand the difference between fact and theory, even if my comment (in the hope of brevity) might not live up to your expectations.

People don't have to know how gravity works to be able to trust that it does. People trust gravity works every time they step or jump, knowing that they will be pulled back down to earth. A similar mindset applies to the speed of light (yes, in a vacuum). It's been observed enough times that though it's technically a theory, it's bankable and can be assumed for all intents and purposes (no one says "well, this techno-gadget is perfect in design, we'll just have to cross our fingers that the speed of light in a vacuum hasn't changed").

On the other hand, climate change theory is constantly evolving. Does CO2 have a major impact on global warming, or are it's effects greatly overshadowed by water vapor which is often left out of many models? Do cows worsen global warming, or do their eating habits cancel their methane out or even decrease the amount of greenhouse gases? Will human CO2 emissions cause temperatures to rise over the next ten years, or will global warming proponents be shocked by a decrease in temperatures and be forced to change the term from 'global warming' to 'climate change'?

If the 'global warming fix' was simple and cheap, I'd say let's play it safe. We may have a problem, we may not, so let's be on the safe side. However, to achieve significant, lasting results in CO2 emission decreases, it will take a DRASTIC change in lifestyle, trillions of dollars in taxes/revenue loss worldwide, and a great risk of being completely swindled by 'green' corporations who (as corporations should) are just looking for profit. With this scenario I say we wait until the theories and models have been sufficiently tested and until the proposed actions have been thoroughly weighed for risk/reward.

Most importantly, enough so that I give it it's own paragraph... we also need to decide that IF we are having an effect on climate, and IF it's possible to reverse that effect, and IF the method of reversal is economically feasible... SHOULD we reverse it? A warmer planet is not necessarily a bad thing. Plants thrive in higher temperature, high CO2-density environments; growing seasons lengthen; human deaths remain relatively unchanged (as opposed to cold weather which raises the death rate). Historically, we're at a high global temperature already; maybe AGW can prevent the next severe ice age (it can't, but that would be nice).

The IPCC says "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities". I don't want new evidence, I want tried and tested evidence. I don't want stronger evidence, I want practically irrefutable evidence. I don't want short term trends, I want a long-term understanding of climate (including solar cycles).

Until 'global warming' or 'climate change' has earned the type of trust we have for gravity, I'll keep my money and my way of life.


Sean Samis


At the risk of a minor digression, and although I am not particularly sympathetic to Brett's position, there is a difference between "gravity" and a "theory of gravity".

"Gravity" is an observable phenomena; calling it a fact is not intolerable.

A "theory of gravity" is an explanation for the observed phenomena ("fact" if you will) of "gravity". It is possible that the CURRENTLY FAVORED gravitational theory will be proven wrong some day; but that will not change the observed phenomena.

Likewise, there are a number of observed phenomena which, taken collectively, indicate global warming. Theories abound trying to explain this phenomena; including theories attributing it to human activity or purely natural events.

The fly in the ointment is that it has turned out to be more difficult than expected to directly measure global warming, in no small part because we have only started trying in the last few decades; most of the valuable, benchmark data occurred in the past; so we have to rely on indirect measurements of past global temperatures.

We might be able to say with great accuracy what the current global mean temperature is, but the essential comparative data is hotly disputed. Meanwhile the indirect evidence of global warming continues to pile up; and persons who reject global warming have not been able to provide a coherent explanation for the indirect evidence.



You still do not believe it? Somebody that way said: "already it will happen". Another one said "the global warming only lives in the brainwashed".

Very strong earthquakes in Haiti, Chile, China.
And now the extreme eruption of the volcano of Iceland.

It said by the Intergovernmental Panel on Climate Change - IPCC in his first books on the physics of the environment: " A delicate balance of forces exists on the environment". It has been violated in only 200 years by the environmental contamination caused by the economic development and the lifestyle of the USA, the developed countries and lately by the emergent countries (China, India and Brazil).

The scientists have given their conclusions on the basis of the global temperature increase and the consequent defrosting of glaciers and poles. But, nothing has been said of that delicate balance that points to the power balance between the Earth nucleus (the magma) and the terrestrial surface. If the last one is being warmed up, so far only 0.8?C, it will not be that the nature is warning us that no longer supports more warming?, and the high internal energy is overcoming the external forces that never had to change?

People in charge hear, stop to warm up the Earth, you are going to destroy it!.

Use all the money you have to put the scientists to seek solution for the global warming problem and suspend all he investigations nonrelated, until a solution is had!


Sean Samis


Gravity itself may be stable, but the theory that explains it remains incomplete (and unstable). If you don't notice that instability it may be because the theory has been worked on since at least the time of Aristotle. Theories explaining global warming are much newer.

Theories of gravity also don't indicate any need to change your life-style while theories of global warming do; so you notice them and are annoyed by them far more than theories of gravity.

Like gravity, the signs of global warming are reliable and unchanging. Unlike gravity, the measurements are harder to take. I can drop a shoe and come up with a fair measure of the force of gravity. Making my own measurement of current global temperature averages is neigh-on to impossible for me as an individual.

You mention changing understandings of the role of CO2, water vapor, and other gases; the contributions of humans and cows (and other living things) to the phenomena. Again, these are part of the theories attempting to explain the phenomena; but the phenomena itself remains; and efforts to explain the phenomena away have failed too.

I doubt that the changes we need to make in our life styles is as drastic as you think; though that's a subjective standard. Some people think adopting the metric system is DRASTIC. It's all about your tolerance for change. Trillions of dollars will have to be spent OVER MANY YEARS to respond to global warming, but to characterize this as a loss is nonsense. Trillions of dollars will be spent over the next many years anyway, and spending money to create new industries, new products and new jobs is not a loss, it's just a change.

Might we be swindled by "green" corporations? No more than traditional corporations swindle us now. I sympathize with your desire to have models and theories thoroughly weighed, but if you are sufficiently change-adverse, there will never be enough certainty until it's too late.

Your paragraph on whether a warmer planet is all that bad omits a significant problem: If the planet gets warm enough to float the Antarctic ice cap (not melt it, just float it), mean sea-level will rise about 200 feet. Any city or population center less than 200 feet above sea-level (currently) will either be drowned, or forced to move. I am not sure of the cost of relocating the human population in this flood-zone, but I am pretty sure that it will run MUCH HIGHER than the cost of reducing our carbon output. And for these people, the effect on their life styles will be DRASTIC at best.

If we wait around for global warming to "earn the type of trust we have for gravity" it may well be too late.



Did Mrhrvold ever respond to the counterargument that his proposal would release vastly less stratospheric SO2 than would be needed to counteract global warming? (IIRC, he was off by a factor of 200 or so by comparison to what we've seen from the effect of volcanic eruptions.)



Not to sound trollish, because I'm quite sincere... but aren't you arguing with yourself between post #13 and post #15?

Eric M. Jones

ScienceDaily (Apr. 15, 2010) - Current observational tools cannot account for roughly half of the heat that is believed to have built up on Earth in recent years, according to a "Perspectives" article in this week's issue of Science.....

Even the theory of gravity is not quite firm. The understanding of global warming is much less than firm.

@Sean Samis

"I believe the peculiar geological history of Venus is attributed to the near absence of water; water serves as a tectonic lubricant (among other things) so tectonic activity on Venus seemed to have frozen until the underlying mantle got so hot it melted the entire crust. Given our abundance of water, that scenario is unlikely on earth."

--A couple billion years ago Venus had as much water as Earth. And so where do you suppose the gazillion tonnes of Venusian water went to?



Your viewpoint seems more political than scientific. Twice you went out of your way to rail against "green" efforts, demonstrating a pre-conceived bias against these efforts and an eventual seeking of evidence to support this previously-drawn conclusion. Now, I don't disagree with you about the shortcomings and failings of the "green" movement. But your disdain for it should not factor into the discussion of the realities of AGW.



Seems like others have answered sufficiently. I'll just say that, as one of the people working on a political solution to global warming, I'll keep doing what I'm doing. You're welcome to keep denying that it's happening if you like - I understand that facts that upset people's worldview can be difficult to accept. I prefer to spend my time working on a solution, rather than argue with people who don't accept that there's a problem.