Chile's volcano not likely to affect the climate

By: Dr. Jeff Masters , 2:01 PM GMT on May 19, 2008

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It's been a busy month for natural disasters, and I haven't found time to talk about Chile's Chaiten volcano, 760 miles (1,220 km) south of the capital Santiago. The volcano started erupting on May 2 for the first time in thousands of years, spewing ash, gas and molten rock into the air, forcing the evacuation of thousands of people. Did this mighty eruption have a cooling effect on the climate?


Figure 1. This May 5, 2008 image from NASA's Terra satellite caught Chaiten erupting. Image credit: NASA.

Many historic volcanic eruptions have had a major cooling impact on Earth's climate. However, Chaiten is very unlikely to be one of them. To see why this is, let's examine recent volcanic eruptions that have had a significant cooling effect on the climate. In the past 200 years, Mt. Pinatubo in the Phillipines (June 1991), El Chichon (Mexico, 1982), Mt. Agung (Indonesia, 1963), Santa Maria (Guatemala, 1902) Krakatoa (Indonesia, 1883), and Tambora (1815) all created noticeable cooling. As one can see from a plot of the solar radiation reaching Mauna Loa in Hawaii (Figure 2), the Mt. Pinatubo and El Chichon eruptions caused a greater than 10% drop in sunlight reaching the surface. The eruption of Tambora in 1815 had an even greater impact, triggering the famed Year Without a Summer in 1816. Killing frosts and snowstorms in May and June 1816 in Eastern Canada and New England caused widespread crop failures, and lake and river ice were observed as far south as Pennsylvania in July and August. Volcanic eruptions cause this kind of climate cooling by throwing large amounts of sulfur dioxide gas into the stratosphere. This gas reacts with water to form sulphuric acid droplets (aerosol particles), which are highly reflective, and reduce the amount of incoming sunlight.

You'll notice from the list of eruptions above that all of these climate-cooling events were from volcanoes in the tropics. Above the tropics, the stratosphere's circulation features rising air, which pulls the sulfur-containing volcanic aerosols high into the stratosphere, where the upper-level winds circulate them all around the globe. These aerosol particles take a year or two to settle back down to earth, since there is no rain in the stratosphere to help remove them. However, if a major volcanic eruption occurs in the mid-latitudes or polar regions, the circulation of the stratosphere in those regions generally features downward subsiding air, and the volcanic aerosol particles are not able to penetrate high in the stratosphere and get carried all around the globe. Chaiten is located near 40° south latitude, far from the tropics, and thus is unlikely to be able to inject significant amounts of sulfur aerosols into the stratosphere. Furthermore, the character of Chaiten's eruptions so far has been to eject a lot of silica and not much sulfur into the air. The total amount of sulfur ejected has been only about 1/10000 of what Mt. Pinatubo put into the air, according to NASA.


Figure 2. Reduced solar radiation due to volcanic aerosols as measured at Mauna Loa Observatory, Hawaii. Image credit: NOAA/ESRL.

Realclimate.org has a nice article that goes into the volcano-climate connection in greater detail. One interesting quote from the article: There can be some exceptions to the tropics-only rule, and at least one high latitude volcano appears to have had significant climate effects; Laki (Iceland, 1783-1784). The crucial factor was that the eruption was almost continuous for over 8 months which lead to significantly elevated sulphate concentrations for that whole time over much of the Atlantic and European regions, even though stratospheric concentrations were likely not particularly exceptional.

My next blog will talk about new research regarding the hurricanes/global warming connection.

Jeff Masters

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390. StormJunkie
6:27 PM GMT on May 19, 2008
Nice Ike ☺
Member Since: August 17, 2005 Posts: 26 Comments: 16607
386. IKE
1:24 PM CDT on May 19, 2008
371. SFLGirl 1:22 PM CDT on May 19, 2008
Avid visitor of this site and really do enjoy the views posted and the learning value. However, can we draw a line in the sand and get a new topic get started?


Back to Global Warming or which candidate is best to lead this country after that terrible president we have now?

Which topic do you prefer?
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385. NEwxguy
6:25 PM GMT on May 19, 2008
Good,Flood,how about yourself,I made it through a long winter ready for some hot weather.
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383. NEwxguy
6:24 PM GMT on May 19, 2008
lol,love the way this blog walks that fine line.
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381. StormJunkie
6:25 PM GMT on May 19, 2008
Almost forgot flood, I threw in a We Bid You Goodnight for my final contribution to the music fest.
Member Since: August 17, 2005 Posts: 26 Comments: 16607
380. Floodman
6:23 PM GMT on May 19, 2008
NEwx, how have you been?
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379. StormJunkie
6:22 PM GMT on May 19, 2008
I am with ya SFLG :~)

Time to move on. Should have been taken as good humor for all though. Hope no one came out of that diatribe seriously offended
Member Since: August 17, 2005 Posts: 26 Comments: 16607
378. weatherblog
6:21 PM GMT on May 19, 2008
Looks like a Tropical Depression already...
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377. NoNamePub
6:23 PM GMT on May 19, 2008
371 - I second...moved on here!
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375. TampaSpin
2:22 PM EDT on May 19, 2008
We better straighten up now JP is lurking.....ROFLMAO
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374. TheCaneWhisperer
6:22 PM GMT on May 19, 2008
Any thoughts on that surface trough in the BOC?
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373. NEwxguy
6:22 PM GMT on May 19, 2008
Tampa,
glad to see some new blood for a change,really like your team.
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372. Floodman
6:21 PM GMT on May 19, 2008
363. So am I!

Can't we all just get along! LOL
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371. SFLGirl
2:22 PM EDT on May 19, 2008
Avid visitor of this site and really do enjoy the views posted and the learning value. However, can we draw a line in the sand and get a new topic get started?
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369. TampaSpin
2:19 PM EDT on May 19, 2008
361. NEwxguy 2:19 PM EDT on May 19, 2008
wow,really getting weird in here,come on tropical season

Newxguy, how about those Rays on you heels...lol

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367. presslord
2:19 PM EDT on May 19, 2008
I second SJ...what's good for the gander...is good for the goose....
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365. Floodman
6:20 PM GMT on May 19, 2008
357. StormJunkie 6:18 PM GMT on May 19, 2008
351.

Well if that is the case then in this day and age of equal rights, I expect to see some....



Careful...
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364. NoNamePub
6:20 PM GMT on May 19, 2008
LOL - It was a joke!
But 358 was the same kind of joke...don't just call me out!
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363. StormJunkie
6:19 PM GMT on May 19, 2008
361. I second that!

I'm working hard to lighten the mood, but things just keep getting odder
Member Since: August 17, 2005 Posts: 26 Comments: 16607
361. NEwxguy
6:15 PM GMT on May 19, 2008
wow,really getting weird in here,come on tropical season
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360. Floodman
6:13 PM GMT on May 19, 2008
337. IpswichWeatherCenter

Hey, Ipswich...just wondering how the A/B High will config itself this year.
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356. jamweather
6:17 PM GMT on May 19, 2008
HOG if u have flaunt it. and it does look good
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353. moonlightcowboy
1:16 PM CDT on May 19, 2008
Okay, we'll save the real honors for TAZ!
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350. presslord
2:15 PM EDT on May 19, 2008
HOG...just stay away from my 19 yr old daughter...other than that, I don't care....
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347. StormJunkie
6:12 PM GMT on May 19, 2008
Wait, maybe I am still ok in Vegas, that says peenhole My money was clearly put down on pinhole...

lol Flood, you beat me to it!
Member Since: August 17, 2005 Posts: 26 Comments: 16607
346. Floodman
6:10 PM GMT on May 19, 2008
SJ, the bet is still on; MLC said "peenhole" eye!
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342. NoNamePub
6:09 PM GMT on May 19, 2008
Congrats on your office - that is really neat!

I seem to remember a girl (or whatever that whole episode last year was) that had to change a pic (or got booted) because it offended some peeps...
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341. Floodman
6:08 PM GMT on May 19, 2008
TS, never better...my eyes are a little bloodshot...sniffing Magic Markers you know...I really miss mimeo machines
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340. StormJunkie
6:09 PM GMT on May 19, 2008
Great, freakin awesome mlc, I just lost big bucks in Vegas thanks to you.

I had my money on Taz being the first one to say pinhole eye this season :~)
Member Since: August 17, 2005 Posts: 26 Comments: 16607

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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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