Thursday, April 29, 2010

Volcanoes And The Extinction Of Us

 "Morn came and went, and came, and brought no day/ And men forgot their passions in the dread/ Of this their desolation . . ."

...Lord Byron wrote this in the aftermath of the Tambora eruption in 1815 which darkened skies over England for weeks. Apparently quite a few artists were profoundly affected by this eruption. Mary Shelley got depressed and wrote Frankenstein while others like JMW Turner painted the bright sunsets that were brought about by haze forming suspended ash all over Europe.

Simon Winchester has a good article in the Guardian on volcanic eruptions of the past and their impact on humans and on their capacity to wreck havoc on global ecosystems.

He comes out distinguishing the aftereffects of earthquakes and volcanoes. Earthquakes kill a lot more people but in terms of long lasting impacts on organisms, volcanoes are more lethal. Earthquakes don't cause extinctions unlike the ill-effects of volcanoes which can linger on for weeks or even years after, resulting in a more widespread environmental damage and extinctions of local and sometimes global reach.

The article is mostly about the impacts of volcanoes on biology but I can't help pointing out that recent massive earthquakes have had very important, potentially long lasting, social impacts of local and regional significance.

After the 2004 Sumatra earthquake, the separatist movement which was gathering strength in the island of Aceh lost steam due to the utter devastation of its population and infrastructure. A peace agreement with the Indonesian government resulted in restoring peace and stability after decades of violence.

On a more villainous note,  in the aftermath of the 2005 Kashmir earthquake, the social arms of the terrorist organizations Lashkar-e-Taiba and Hizbul Mujahideen rushed in to provide help to the local populations in the absence of prompt government relief and gained enormous popular support making it that much harder to uproot them.

Coming back to the minor quibble I have is about his section on the rates of mass extinctions. He says that two to 5 major extinction events occur in the world every million years or so. This is in reference to "profound and world changing" mass extinctions and I am puzzled by this statistic. Surely he means every few tens of millions of years or so, especially since he is linking these events to flood basalt volcanism? Or does he mean flood basalts from Iceland volcanoes in the past few million years have triggered mass extinctions on a million year frequency? Extinction is occurring all the time and occasionally there will be a spike over and above the background extinction rate brought about by catastrophic events, local and regional and only rarely global ..but what does he exactly mean by "two to five major extinction events"? are these local or global events...and do we really have paleontological methods to resolve events that closely spaced?

Iceland sits atop a mantle hot spot that coincides with a mid-oceanic ridge. This underlying heat engine may be the modern representative of the hot spot responsible for past flood basalts provinces of Greenland and in the British Isles which formed during the early Cenozoic opening of the north Atlantic.  Seen in this context, is the recent Iceland eruption the beginning of a more prolonged volcanic activity that might threaten our very existence?

That's off course pure speculation in an article that is otherwise full of information and interesting facts..but it does make you a bit uneasy....

Tip: Nanopolitan

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