Saturday, April 24, 2010

"Abrupt climate changes possible"


Foto: Lago Atitlan in Guatemala

Yes, abrupt climate change is possible and fairly common if you study the historical and geological record of the earth.

........The prize for the largest super volcanic eruption goes to the La Garita eruption in the San Juan Mountains of SW Colorado, USA, some 29 million years ago. About 1,200 cubic miles of debris was scattered over the adjacent region, together with similar large explosions within a few million years.

Tourist regions of note that have developed around caldera lakes include the beautiful Lago Atitlan in the NW highlands of Guatemala. This super volcanic eruption occurred 84,000 years ago ejecting 300 cubic kms of tephra and leaving a caldera lake measuring 7 to 17 kms across, now surrounded by a number of more recent dormant and smoking volcanic cones.

The most recent super volcanic eruption happened a mere 1800 years ago (ca 186 AD) in New Zealand with an enormous explosion in the center of the North Island ejecting ca 110 cubic kms of ash and pumice. What is left is a caldera lake (Lake Taupo) of size about 30 kms across, now stocked with rainbow trout, and has become a famous tourist region. Fortunately no humans beings were there at the time of this eruption (one of many) , since the first Polynesian migration by outrigger canoe occurred about 1100 AD.

There are many conclusions that can be drawn from this brief overview of abrupt climate changes that have occurred in the recent and distant past.

Firstly, .......
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