Global Warming to cause more Earthquakes & Eruptions?

[jasons2k]

http://www.guardian.co.uk/science/2007/aug/07/disasters

The Earth fights back
Never mind higher temperatures, climate change has a few nastier surprises in store. Bill McGuire says we can also expect more earthquakes, volcanoes, landslides and tsunamis

Guardian Unlimited Tuesday August 7 2007

Unlike most apparently intractable problems, which have a tendency to go away when examined closely and analytically, the climate change predicament just seems to get bigger and scarier the more we learn about it.

Now we discover that not only are the oceans and the atmosphere conspiring against us, bringing baking temperatures, more powerful storms, floods and ever-climbing sea levels, but the crust beneath our feet seems likely to join in too.

Looking back to other periods in our planet's history when the climate was swinging about wildly, most notably during the last ice age, it appears that far more than the weather was affected. The solid earth also became restless, with an increase in volcanic activity, earthquakes, giant submarine landslides and tsunamis. At the rate climate change is accelerating, there is every prospect that we will see a similar response from the planet, heralding not just a warmer future but also a fiery one.

Several times in the past couple of million years the ice left its polar fastnesses
and headed towards the equator, covering much of the world's continents in ice sheets over a kilometre thick, and sucking water from the oceans in order to do so. As a consequence, at times when the ice was most dominant, global sea levels were as much as 130m lower than they are today; sufficient to expose land bridges between the UK and the continent and Alaska and Russia.

Each time the ice retreated, sea levels shot up again, sometimes at rates as high as several metres a century. In the mid 1990s, as part of a study funded by the European Union, we discovered that in the Mediterranean region there was a close correlation between how quickly sea levels went up and down during the last ice age and the level of explosive activity at volcanoes in Italy and Greece.

The link was most obvious following the retreat of the glaciers around 18,000 years ago, after which sea levels jumped back up to where they are today, triggering a 300% increase in explosive volcanic activity in the Mediterranean in doing so. Further evidence for a flurry of volcanic action at this time comes from cores extracted from deep within the Greenland ice sheet, which yield increased numbers of volcanic dust and sulphate layers from eruptions across the northern hemisphere, if not the entire planet.

Read the full content……

But how can rising sea levels cause volcanoes to erupt? The answer lies in the enormous mass of the water pouring into the ocean basins from the retreating ice sheets. The addition of over a hundred metres depth of water to the continental margins and marine island chains, where over 60% of the world's active volcanoes reside, seems to be sufficient to load and bend the underlying crust.

This in turn squeezes out any magma that happens to be hanging around waiting for an excuse to erupt. It may well be that a much smaller rise can trigger an eruption if a volcano is critically poised and ready to blow.

Eruptions of Pavlof volcano in Alaska, for example, tend to occur during the winter months when, for meteorological reasons, the regional sea level is barely 30cm (12in) higher than during the summer. If other volcanic systems are similarly sensitive then we could be faced with an escalating burst of volcanic activity as anthropogenic climate change drives sea levels ever upwards.

Notwithstanding the recent prediction by the Intergovernmental Panel on Climate Change (IPCC) that sea levels in 2100 will be a measly 18-59cm (7-23in) higher, Jim Hansen – eminent climate scientist and director of NASA's Goddard Institute for Space Studies – warns that we could see a one to two metre rise this century and several more in the next. Other climate scientists too, forecast substantially greater rises than the IPCC, whose prediction excludes any consideration of future changes in polar ice sheet behaviour. A worst-case scenario could see a return to conditions that prevailed around 14,000 years ago, when sea levels rose 13.5 metres (44ft) - the height of a three-storey house - in the space of about 300 years.

Such a dramatic rise in coming centuries would clearly spell catastrophe for our civilisation, with low-lying regions across the planet vanishing rapidly beneath the waves. Just a one metre (3.28ft) rise would threaten one third of the world's agricultural land, two metres (6.56ft) would make the Thames flood barrier redundant and four metres (13.12ft) would drown the city of Miami, leaving it 37 miles (60km) off the US coast.

As sea levels climb higher so a response from the world's volcanoes becomes ever more likely, and perhaps not just from volcanoes. Loading of the continental margins could activate faults, triggering increased numbers of earthquakes, which in turn could spawn giant submarine landslides. Such a scenario is believed to account for the gigantic Storegga Slide, which sloughed off the Norwegian coast around 8,000 years ago, sending a tsunami more than 20 metres (66ft) high in places across the Shetland Isles and onto the east coast of Scotland. Should Greenland be released from its icy carapace, the underlying crust will start to bob back up, causing earthquakes well capable of shaking off the huge piles of glacial sediment that have accumulated around its margins and sending tsunamis across the North Atlantic.

The Earth is responding as a single, integrated system to climate change driven by human activities. Global warming is not just a matter of warmer weather, more floods or stronger hurricanes, but is also a wake-up call to Terra Firma. It may be no coincidence that one outcome of increased volcanic activity is likely to be a period of falling temperatures, as a veil of volcanic dust and gas reduces the amount of solar radiation reaching the surface. Maybe the Earth is trying to tell us something. It really would be worth listening before it is too late.

Bill McGuire is the director of the Benfield UCL Hazard Research Centre. His book Surviving Armageddon: Solutions For a Threatened Planet is published by OUP. His next book, What Everyone Should Know About the Future of Our Planet: And What We Can Do About It, is published by Orion in January next year.

[x-y-no]

Hmmm ...

It looks like what they're suggesting is that a large, rapid increase in sea level can sufficiently deform the crust to cause earthquakes and volcanic activity.

My comment on that is that unless we have a catastrophic failure of either the Greenland or West Antarctic ice sheets, we won't be seeing such a large and rapid increase in sea level. And if we do have such a catastrophic failure, then volcanic activity will be a relatively minor part of our problems.

[HURAKAN]

It doesn't make sense because if you put more water you are going to produce more pressure. Since we have a global ocean, meaning that all the "oceans" are connected, then the pressure is going to be directed towards Earth's center. Which in turn would make it a little bit more "harder" to move the plates.

What is interesting is that in the Northern Hemisphere most of the land is "moving up" and has been doing that since the last Ice Age. The ice caps caused the land to "sink" because of the weight, and now that there is no weight the land moving back up.

I really don't see his hypothesis coming to reality in my mind.

[x-y-no]

Well, the issue is that pressure isn't uniform over the globe - it's confined to the ocean basins. This would lead to some amount of deformation at the boundary between land and ocean plates.

Also, I don't really see this affecting the mobility of plates in general - the force of magma movement under the plates is far higher than added pressure we're talking about here.


Anyway, much as I'm concerned about global warming, this threat isn't particularly high on my list of concerns.

[chadtm80]

Just more Scare Tactics jschlitz... Just more scare tactics

[MGC]

The sky is falling......MGC

[fasterdisaster]

Even as a liberal in favor of a much stricter global warming agenda than the one currently I have to say the majority of the article is silly. The only thing in that article that would MAYBE be affected is volcanic eruptions, and even that's pushing it. Let me tell you, it takes FAR MORE energy than anything a high sea level could do to move a tectonic plate. And the only reason there would be more landslides is because the increased rainstorms and hurricanes would cause it.

[gigabite]

http://home.att.net/~gigabite/PLASMASHIELD0507.gif

At the August 28, 2007 crossing of the Moon into the northern hemisphere there was a dramatic thinning of the dayside cloudiness of the metrological equator in the northern hemisphere along with a forcing of water vapor into the southern hemisphere. I suggest that this was caused as a result of tidal plasma migration to the bow of the ionosphere following the run up to the New Moon. This uncharacteristically large displacement of water vapor has to be the result of a thickening up of plasmasphere as a result of a stable Earth Sun Aphelion Distance.

That may sound counterintuitive, but the norm is for the Earth Sun Aphelion Distance to vary alternately by a couple of percent every year. That may not seem like much, but a 1% change in the Earth Sun distance is a 1000 Earth diameters. What happens is that one summer we are 2000 Earth Diameters closer to the Sun and the next summer we are 2000 Earth Diameters further away, normally. That did not happen this year. This year we are nearly the same distance from the Sun as we were last year at the furthermost point from the Sun. that means that the plasma shield ( the plasmapause ) has not had the opportunity to drain plasma in the usual manner.

As the plasma shield thickens the distance between the bottom of the plasma shield and the Earth’s surface is reduced which increases atmospheric pressure. The result of this increased high pressure will be a reduced number of tropical storm from the analog year. Also the lack of moisture may factor into faster trade winds and a low chance of tropical storms curving to the right.

And although only a small fraction of the increased intensity of the radiation increase due to the current solar minimum reaches the earth directly it seems reasonable to me that if that energy is not transferred as heat to the upper atmosphere that it must at least expand the thickness of the plasmasphere, because it is not reasonable that is all dissipated into space instantly.

http://home.att.net/~gigabite/ORBITDISTvsHURFRQ.gif

Tropical storm frequency seems to increase as the length of the earths major orbit axis increases. This could be because as the orbital axis shortens the plasma shield tickens and global high pressure increases creating blocking limiting front movement and tropical cyclone development.

High pressure and blocking events are likely to increase as the aphelion distance decreases over the next thousand years. This will probably limit rainfall and what rain does fall will be concentrated along stalled frontal boundaries causing localizes flooding, and increase the likelihood of upheaval. Just a thought.