http://news.bbc.co.uk/hi/english/sci/tech/newsid_628000/628515.stm

Supervolcanoes could trigger global freeze

By environment correspondent Alex Kirby

The threat of climate change caused by human activity could turn out to be a minor problem by comparison with a scarcely acknowledged natural hazard.

Geologists say there is a real risk that sooner or later a supervolcano will erupt with devastating force, sending temperatures plunging on a hemispheric or even global scale.

A report by the BBC Two programme Horizon on one supervolcano, at Yellowstone national park in the US, says it is overdue for an eruption.

Yellowstone has gone off roughly once every 600,000 years. Its last eruption was 640,000 years ago.

Professor Bill McGuire, of the Benfield Greig Hazard Research Centre at University College, London, told BBC News Online: "We're getting ready for another eruption, unless the system has blown itself out.

"But the ground surface deformation and other signs measured by satellite suggest it's still active, and on the move."

Molten rock

Typically, supervolcanoes are not mountains but depressions, huge collapsed craters called calderas, which are hard to detect.

The Yellowstone caldera is 70 kilometres long and 30 km wide. Eight km beneath the Earth's surface lies a huge magma chamber, containing vast amounts of molten rock.

As pressure rises in the chamber, the surface is also rising and there is a measurable increase in heat. But vulcanologists do not know when Yellowstone will blow.

Professor McGuire, whose book, Apocalypse! A natural history of global disasters, portrays a possible Yellowstone explosion in 2074, says there have been two such events every 100,000 years for the last two million years.

The areas where supervolcanoes are most likely to be found, he says, are subduction zones, where the Earth's plates are dipping below one another. The Pacific Rim and southeast Asia are especially vulnerable.

But there is a caldera in the Phlegraean Fields near Naples in southern Italy. Dr Ted Nield, of the Geological Society of London, told BBC News Online: "It could do the same as Yellowstone, though on a smaller scale".

Nuclear winter

"When a supervolcano goes off, it is an order of magnitude greater than a normal eruption. It produces energy equivalent to an impact with a comet or an asteroid.

"You can try diverting an asteroid. But there is nothing at all you can do about a supervolcano.

"The eruption throws cubic kilometres of rock, ash, dust, sulphur dioxide and so on into the upper atmosphere, where they reflect incoming solar radiation, forcing down temperatures on the Earth's surface. It's just like a nuclear winter.

"The effects could last four or five years, with crops failing and the whole ecosystem breaking down. And it is going to happen again some day."

Ice-core records show that the eruption of Toba in Sumatra about 74,000 years ago may have caused global cooling of from three to five degrees Celsius, and perhaps as much as 10 degC during growing seasons in middle to high latitudes.

Even ordinary volcanoes can affect the climate. When another Indonesian volcano, Tambora, erupted in 1815, several years of globally cold weather followed, with the annual global mean surface temperature about one degree Celsius below normal.

The Geological Society, in evidence to the UK Parliament, is urging more research into the risk from supervolcanoes and their probable climatic effects.

-- Thar she blows (@ .), February 03, 2000

Answers

sounds like everyone should store at least 5 yrs worth of food .. just in case. and i Hate the cold.

-- lou (lanny1@ix.netcom.com), February 03, 2000.

Underground Cities -- start digging ;^)

-- Ashton & Leska in Cascadia (allaha@earthlink.net), February 03, 2000.

Damn! Just when I was getting used to the idea of global warming! Any change that one could balance out the other? At least I won't have to worry about the polar caps melting and the water coming into my house in Miami! I'm off to get some more firewood...

-- JoseMiami (caris@prodigy.net), February 03, 2000.

Hey, keep your video camera handy. CNN would pay for a tape of THAT!

-- Tom Carey (tomcarey@mindspring.com), February 03, 2000.

Supervolcanoes are easy to spot. They are the ones with the big red "S" attached to them

-- cjs (cjs@cjs.com), February 03, 2000.

Okly 24,790 days left. Are you prepared?

-- (MikeH@preps.galore), February 03, 2000.

Do scientists know what happened when Kwajalein erupted??

The width of that crater is some 47 miles wide!

-- K. Stevens (kstevens@ It ALL went away last month.com), February 03, 2000.

Let's make sure no russians with bulky backpacks go slippin' into yellowstone with demolition on their minds... (grin)

-- Possible Impact (posim@hotmail.com), February 03, 2000.

Looks like I might need my 1,100 pounds of beans and all that TP after all. Now if there is just some way to harness all the gas that's going to be produced, maybe we can move that old temperature up a notch or two.

-- Sharon L (sharonl@volcano.net), February 03, 2000.

All you global warming types best get on this quickly. You will never succeed in de-industrializing the world if word of this gets past sympathetic media outlets.

-- JB (noway@jose.com), February 03, 2000.

Tom:

Have you been in the Yellowstone caldera? If that thing went off, you would want to use a long lens and shoot from London :o). I used to live just north of there. I never heard of [or saw] any activity in that area. It is an interesting area but not something that I worry about [in that area, earthquakes and (except for this year) snow are a more immediate problem].

Best wishes,,,

-- Z1X4Y7 (Z1X4Y7@aol.com), February 03, 2000.

cjs, LOL! and blue tights, huh? hehe

-- Hokie (Hokie_@hotmail.com), February 03, 2000.

---outstanding, cjs! Best, shortest guffaw in awhile. Me an Hokie are impressed, at least! Long rule the jokesters!

-- zog (zzoggy@yahoo.com), February 03, 2000.

Re Yellowstone. This isn't a "could" it's a "will". The underground magma reserve is there, easy to determine with seismometry. It's expanding, causing the ground to rise 75cm in 50 years in parts of Yelllowstone. It's about THREE HUNDRED THOUSAND CUBIC KILOMETERS of molten rock full of highly compressed volcanic gases in solution, about 8km down. Sometime in the next 100,000 years it'll blow. It last blew about 600,000 years ago, and before that about 1.2M and 1.8M years ago. Spot the pattern? Scary.

The evidence for world climatic catastrophe when the last Supervolcano blew is also extremely clear (74,000 years ago in Indonesia). It's also well-proved that humanity went through a "genetic bottleneck", a time when the entire population of the species was reduced to a few thousand or less. Dating this is rather less certain, but those who think that current ribosomal mutation rates are constant over time get a date of ... guess ... 75,000 years ago, give or take a few thousand.

Altogether nightmarish.

-- Nigel (nra@maxwell.ph.kcl.ac.uk), February 04, 2000.

Nigel:

What you say is true, but that doesn't make it a will. Your timing for the genetic bottleneck in humans is something that could, will, is argued on a regular basis [I presume that you are talking about the intervening sequence data]. It may [that is an if] go of in a few hundred thousand years. Hell, modern humans haven't been here all that long [based on the same clock], we may not be here then. If you want to worry, there are more immediate concerns. If you want to write best selling science fiction, this is a good story.

Best wishe

-- Z1X4Y7 (Z1X4Y7@aol.com), February 04, 2000.

well i have a question. what would happen to all the region immedialtly affected . get burned to ashes.. damn there goes cali...

-- jonathan (korkinakos@yahoo.com), January 21, 2005.

I was wondering why somebody revived this thread, and then I noticed this topic is in the news today.

http://www.technewsworld.com/story/news/39923.html

Research Offers New Extinction Theory

UPI

01/21/05 10:37 AM PT

The Great Dying is considered the biggest catastrophe in the history of life on Earth, with 90 percent of marine life and three-quarters of land-based plant and animal life going extinct. The culprit might have been atmospheric warming because of greenhouse gases released by erupting volcanoes.

The theory a comet or asteroid triggered the biggest mass extinction in Earth history is being disputed by new research.

In a paper published Thursday by Science Express, the online version of the journal Science, the researchers say they have found no evidence of an impact at the time of "the Great Dying" 250 million years ago.

Instead, their research indicates the culprit might have been atmospheric warming because of greenhouse gases triggered by erupting volcanoes.

The Great Dying is considered the biggest catastrophe in the history of life on Earth, with 90 percent of all marine life and nearly three-quarters of land-based plant and animal life going extinct.

"Animals and plants both on land and in the sea were dying at the same time, and apparently from the same causes -- too much heat and too little oxygen," said paleontologist Peter Ward of the University of Washington, lead author of the paper.

© 2004 United Press International. All rights reserved.

© 2004 ECT News Network. All rights reserved.

-- (in@the.news), January 21, 2005.