Maybe you've heard that volcanic eruptions can affect climate, but new evidence suggests it happens the other way around, too.
By Emily Elert Posted 12.27.2012 at 11:00 am 21 Comments

Redoubt Volcano, Alaska
Redoubt Volcano, Alaska R.J. Clucas/USGS

Here's an idea you've probably heard before: volcanic eruptions--the big, explosive Pinatubo kind--spew millions of tons of sulfur dioxide into the stratosphere, and the sulfur dioxide stays there for a few years, reflecting sunlight and cooling down the planet for a few years. In other words, eruptions can affect climate.

But new evidence suggests that the volcano-climate relationship can go the other way, too: Periods of warming after ice ages can lead to volcanic eruptions.

In a recent study, a team of geologists examined samples of sea-floor mud from around the Ring of Fire for evidence of past eruptions. Preserved within the million-year mud record were tell-tale layers of ash from 91 volcanic eruptions. Since mud accumulates at a regular rate, the researchers could use the position of the ash layers to date each of the volcanic events.

When they analyzed the frequency of ash layers in the record, the researchers found a pattern: large eruptions tended to occur once every 41,000 years. Random as that number may sound, it's as familiar to paleoclimatologists as the moon's 28ish-day cycle is to the rest of us: over the course of 41,000 years, the Earth tilts gradually forward, and then backward, on its axis. It's called "Obliquity," and it's one of the three "Milankovitch Cycles" that happen over long time periods and influence Earth's climate. They are hard to visualize, so here's some really nice help:

Scientists think that the regular changes in Earth's tilt may have a big effect on the start and end of Earth's ice ages. The planet's tilt is what gives us our seasons--when the northern hemisphere is tilted toward the sun, the days are longer and warmer; when Earth swings around to the other side of the sun and the northern hemisphere is tilted away, the days are shorter and colder--and, when the tilt decreases, the seasons become less intense. At high latitudes, less intense seasons may mean that the summers don't get warm enough to melt all of winter's ice; eventually, those cold summers add up to an ice age.

So, how could an ice age trigger a volcano? The answer is deceptively straightforward: When an ice age starts, the world's water shifts some of its weight from ocean basin to land, and the continents get compressed by the vast, miles-thick ice sheets sitting on top of them. When things warm up, the ice begins to melt and run back into the oceans, taking a great load off of the continents. All this movement pushes around magma under the continents' surface, the same way one end of a water balloon bulges out when you squeeze the other end, and a sudden decrease in pressure over the land may cause magma to surge upward from deep below.

The climate-volcano connection doesn't apply to Earth's current warming trend, of course, because we're not in the middle of an ice age--it's been 12,000 years since the world's continents felt the weight of all that frozen water. (And yes! When it melted, there were lots more eruptions than normal!)

21 Comments

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Phaggamemnon
12/27/12 at 1:02 pm

This is why I don't put much faith in OUR effect on global warming.... The Sun, Gravity, and Physics those are the ones that lead the dance with Mother Nature... we are nothing more then bellhops to entrance of the grand solar ballroom...

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Kehvan
12/27/12 at 1:06 pm

I wonder how many people are now going to claim every volcano is a result of human activity?

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Phaggamemnon
12/27/12 at 1:08 pm

Haha Brilliant never even thought of that ... Then again 1000's of prehistoric virgin sacrifices can't be wrong right?

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Manannan
12/27/12 at 2:47 pm

If you are going to post this type of a story do a little more research.

Here is a quiz for you. What is the #1 greenhouse agent.
I'll give you a clue. It isn't CO2. It isn't CO. It isn't sulfur dioxide.
Volcanos spew out massive amounts of water vapor. Water vapor is the number 1 greenhouse agent.

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Phaggamemnon
12/27/12 at 3:10 pm

Correct nor does it reference all the greenhouse gases nor should it it.. THAT'S NOT WHAT ARTICLE IS ABOUT!!!

-Save a rant teach a troll how to read-

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EmilyElert
12/27/12 at 3:39 pm

@Manannan, you're right that water vapor is a major greenhouse gas, but the biggest climatic impact from volcanic eruptions is due to sulfur dioxide, which converts to sulfuric acid and then condenses to form sulfate aerosols in the stratosphere; those aerosols scatter incoming light and cool Earth. For evidence about volcanic eruptions' influence on the climate, see the global temperature record in the years following the 1991 Pinatubo eruption or the 1816 Year Without A Summer following the eruption of Mt. Tambora.

I have seen studies (see link below) proposing that water vapor in the stratosphere after eruptions may have a mediating impact on the global cooling caused by the sulfate aerosols, but I've never seen a study saying that water vapor can actually warm the climate after an eruption.

That would be really surprising, given that the atmospheric residence time of water vapor is only about nine days, and most of the vapor in volcanic plumes condenses to liquid form as the plume rises. So even though volcanoes spout lots of water vapor, the only stuff that really matters is the portion that makes it into the stratosphere, where it can stay for years (the only way to increase the amount of water vapor in the lower atmosphere over a long period of time is by increasing the air temperature, since humidity is temperature-dependent).

(here's a study on water vapor and volcanoes from 2009: http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&ved=0CFMQFjAD&url=http%3A%2F%2Fwww.atmos-chem-phys.net%2F9%2F6109%2F2009%2Facp-9-6109-2009.pdf&ei=bajcUOmmGc20qQHOhIDgBQ&usg=AFQjCNF5g_BsrnuIv1owtjqA9QituyHvKA&bvm=bv.1355534169,d.aWM)

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Phaggamemnon
12/27/12 at 3:53 pm

Again while all the fact about green house gases are correct being posted above lol still not what the article is about lol..

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democedes
12/27/12 at 6:18 pm

@Manannan

The first hint that you don't have a clue about what you are talking about is that you say that "Water vapor is the number 1 greenhouse agent". Twice. What precisely does #1 mean in this context? Was it voted most popular? Did it win a tournament?

While water vapor is the most prevalent green house gas (I can only hope this is what you meant), it actually cools the planet. Water evaporation is endothermic and more than compensates for the additional heat trapped in the atmosphere. It also makes clouds, which reflect some of the suns energy back into space.

The reason why water vapor was not mentioned is because the water vapor from a volcano doesn't stick around long enough in the atmosphere to affect climate. And since this article is about how volcanoes relate to climate change, not weather change, water vapor released from the volcano is irreverent.

Before you post a comment to an article suggesting a person doesn't know what they are talking about, you should do also do little research. Or you will look like an ass. I speak from experience.

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kyrstinreindl
12/27/12 at 6:56 pm

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quasi44
12/27/12 at 7:08 pm

@ Kehvan, Phaggamemnon, and anyone else interested; Here's the number. 1.63 TRILLION TONS PER YEAR. The current lowball calculation of the various greenhouse gases we put up there each year, and we know it has never gone down worldwide since 1900. Do you have any real concept of what that is? Just how much do you think the whole world weighs? I'll just tell you. About 1000 trillion tons. GET IT YET? 1.63 trillion tons this year, or 1-1000th +- of the total weight of Earth, we put that much crud and gases up there; that are normally only there in times like what's spoken of here, widespread volcanic activity. So, the current estimates of how long this planet can possibly harbor humans SHOULD BE 2.1-2.3 billion years, but COULD BE only 500. That's the math. Prove me wrong, skeptic.

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cojoda
12/27/12 at 9:35 pm

@ quasi44
Your figures for the weight of the world is a tad off. I got 6.584759016×10²¹ tons or 6.58 billion trillion tons. Which means 1.63 tons is equal to approx. 1/4,000,000,000 of the earths weight.

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cojoda
12/27/12 at 9:37 pm

Correction, I meant 1.63 trillion tons.

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iambronco
12/28/12 at 8:00 am

@Quasi44
Earth's weight is approximately 6.6*10^21 short tons.

It appears you may be using long scale to express the earths weight is terms of million/billions/trillions. Using the long scale (billion is a million million, trillion is a million billion), you're correct... earth's weight is approximately on the order of "1000 trillion tons".

Using the long scale, a trillion is 10^18, so 1000 trillion is 10^21.

Unfortunately, the global greenhouse gas emissions estimate of "1.63 trillion tons" you quoted very likely uses the short scale (billion is 1000 millions, trillion is 1000 billions).

Using the long scale, a trillion is 10^12, so 1000 trillion would be 10^15. 10^15 tons is 6 orders of magnitude (1 million times) lower than the actual weight of earth. that results in the greenhouse gas emissions you cited being 1/1000000000 of the earths weight, not 1/1000.

I suggest that in the future, you not express your 'math' in non-scientific terms such as trillions or billions... it may be impressive to laymen, but you're surely setting yourself up for failure.

Moral of the story; ALWAYS CHECK YOUR UNITS!

http://en.wikipedia.org/wiki/Long_and_short_scales

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Robot
12/28/12 at 8:55 am

Bada bing, Bada boom, crack goes the Earth, ka boom, ka powie screams Mother Nature!

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Phaggamemnon
12/28/12 at 5:16 pm

Thanks for the math corrections.. yes we do not emit 1/1000 of the earths weight into the atmosphere every year lol.. I mean didn't anything trigger are you put that as wrong? Someone has some spacial reasoning issues ;).

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quasi44
12/28/12 at 8:01 pm

@ EVERYONE!!!! Yeah, I screwed that all up, and then used my screw up for my result calc. I checked a few comparison estimates of Earth 'weight', and got lost in my own bs. Most times when I put a number to something, it's one I've known for a while. I knew the greenhouse gas number, but not the Earth 'weight' guesstimates.
I did actually realize my lameness last night, and really had hoped to get on here to beat you all to it today.

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riff_raff
12/29/12 at 12:35 am

The earth's climate temperature is a result of solar activity. Period.

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Robot
12/29/12 at 11:55 am

What is the point of PoPSCi changing the order of people’s comments. If you look at the time, they change the order. I guess they wish to manipulate the conversation and the perception of peoples comments. Read the time stamps of the comments.

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steve.smith.tn
12/30/12 at 1:48 am

I wish there were phenomenon that had nothing to do with global warming. Global warming has become inescapable: Popular Science - 5 stories on the front page; New York Times - "5 best vintages caused by global warming;" WebMD - "kids losing their teeth faster because of global warming;" Con De Naste - "Nebraska: the soon to be beach escape of the wealthy."

Enough already. There is no such thing as climate stasis. We get it.

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AlexTada
01/04/13 at 12:31 am

That explains Aryan invasion of India from Europe and creation of first apartheid called caste 12000 years ago

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riff_raff
01/07/13 at 12:40 am

"...I wish there were phenomenon that had nothing to do with global warming. Global warming has become inescapable...."

steve.smith.tn-

Consider this "inescapable" relationship: You claim the earth has been warming due to human activity for the past century. During that same period, the lifespan of the average human has increased by around 20%. Do you feel this is a bad thing?


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