Chile's volcano not likely to affect the climate
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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Wasn't that how STS Andrea got started exept directly over the Gulf Stream.
:c)
The ITCZ, imo, and from what I've read and seen others say, hasn't moved further north just yet because of what has been slightly less than normal surface temperatures. In the ITCZ, SST's and convergence activity go hand-n-hand. As the SST's warm further north, so will activity.
The mid-latitudes have had several deep moving troughs in recent months that have aided the "cooling" of SST's in those areas. That's all about to change as they continue to warm and climatology will find the ITCZ right where it normally should be....where water is warm and the seasonal pitch to the sun takes place.
From my "ITCZ" blog earlier this season.
MYSTERY of the ITCZ What Keeps the ITCZ North of the Equator?
It is a long-standing mystery that the ITCZ stays north of the equator over the Atlantic and eastern Pacific Oceans despite that the annual-mean solar radiation at the top of the atmosphere is symmetric with respect to the equator. This article reviews recent progress that has shed new light on this old puzzle.
(excerpt in part)...The ITCZ problem thus involves a circular chicken-and-egg argument. The ITCZ stays north of the equator because SST is higher; and the SST is higher north because the ITCZ stays there. The positive WES feedback is at the center of this circular argument. In a coupled ocean-atmosphere model, the WES feedback destabilizes the symmetric climate, leading to an asymmetric steady state with a single ITCZ on only one side of the equator (Xie and Philander 1994). A condition for this spontaneous development of latitudinal asymmetry is the equatorial upwelling that prevents the ITCZ from forming at the equator. This necessary condition thus explain why climatic asymmetry only develops over the eastern Pacific and Atlantic where the equatorial upwelling is observed.
(Complete article here.)
I'll see if I can find you a couple of comparisons.
what do you think about the severe weather thats comeing up this weekend???
Subtropical Storm Andrea is hardly the first pre-June 1 named storm of any hurricane season on record, said Greg Romano, a spokesman for the National Weather Service.
“[Early storms] are not rare, but they’re not common," he said. "It’s fair to say they’re uncommon.”
As recently as 2003, Tropical Storm Ana formed on April 20.
Eighteen tropical storms and four hurricanes have formed in May since 1851, and six storms have formed before the June 1 start since 1951. The earliest observed hurricane in the Atlantic formed on March 7 in 1908. Link
- Drak, lol. That's what my old boss used to say, too. I told him we needed the equipment first to produce the egg! LOL
The mid-latitudes have had several deep moving troughs in recent months that have aided the "cooling" of SST's in those areas. That's all about to change as they continue to warm and climatology will find the ITCZ right where it normally should be....where water is warm and the seasonal pitch to the sun takes place.
- Drak, lol. That's what my old boss used to say, too. I told him we needed the equipment first to produce the egg! LOL
The egg is basic and it creates life need to produce more life.
Also your ITCZ blog was read by me recently too. Thanks for that as well.
I'll keep going and see what I can find boat
Having a hard time meeting all of your criteria Boat :~)
Back to the list
ooh, Alice 53...So close, but only TS
The problem with 1 in '52 is that I'm not convinced that it IS part of the '52 season...closer to the '51 season, you think, SJ?
I met the current EU Ambassador here the other day. He says " which hill over there is the hill that they are installing the new radar on ?"
Was news to me, but it turns out that the European Union is funding a weather radar here, just 2 miles south of me, and it should be up and running in June !
Will keep you posted.
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
600 PM PDT TUE MAY 20 2008
ALONG WITH LOW PRESSURE AROUND 990MB
INLAND WILL CREATE INTENSE PRESSURE GRADIENT. NOT OUT OF THE
QUESTION SOME AREAS WILL ENTER HIGH WIND WARNING CRITERIA BY THU
AFTERNOON...BUT WILL WAIT ANOTHER 24HRS TO MAKE CALL ON THAT. BY
00Z FRI...GFS PLACES BULLSEYE OF 135KT 250MB JET RIGHT OVER HEART OF
THE BAY AREA WITH WINDS JUST OFF THE DECK AT 70KT IN NEAR-SHORE
COASTAL WATERS
will this be the same storm that will have severe weather this weekend???
08 made landfall as TS though
Same issue here flood
SJ, that one has a very inteseting path for a storm at that time of year...you'd expect a west to east path, huh?
Perhaps the reason the ITCZ has remained low inland S.America, is that there has been consistent heavy rainfall there for a couple months, keeping land temps down ?
Just a thought.
posts are lagging...didnt they perform maintenance on the server today?
===
Yes around 1730 UTC (earlier today)
No going to watch this weather for a few. Great light show!
See y'all in a minute :~)
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