Tuesday, September 11, 2012

The sixth extinction

Not a DNA Barcoding sensu stricto post today but I really like to introduce a series I discovered at The Guardian which is very well done and worth some recurrent visits.

The Cretaceous-Tertiary (or K-T) extinction event 65 Million years ago is probably the most well-known because it wiped out the dinosaurs. However, a series of other mass extinction events has occurred throughout the history of the Earth, some even more devastating than K-T. Mass extinctions are periods in Earth's history when abnormally large numbers of species die out simultaneously or within a limited time frame. The most severe occurred at the end of the Permian period (248 Million years ago) when 96% of all species perished. This along with K-T are two of the Big Five mass extinctions, each of which wiped out at least half of all species. While the reasons for these five major events are still under discussion and many models have been proposed, there is a sixth major extinction event happening at present and the reasons for this one are quite well understood. Earth is currently losing something on the order of 30,000 species per year. Statistically more dramatically expressed: three species per hour. The so-called Sixth Extinction is the first one that is caused by a species living on the planet: humans are the direct cause of ecosystem stress and species destruction in the modern world and therefore the main driver.

The series at the Guardian is called "The sixth extinction" and presents the current state of knowledge and provides examples for species at the brink of extinction but also conservation efforts that let one hope. Very good articles, well researched, and diverse. I believe the series is already running since beginning of September but all articles and audio files are still available. Today a rather sad record list has been published - the World's 100 most endangered species which was released today by the Zoological Society of London and the International Union for Conservation of Nature.

Reading these contributions makes you pause for a moment and wonder if there will be an end to it. Back in 2005 the renowned Paleontologist Niles Eldrege wrote the following on the question if this extinction can be stopped:

Though it is true that life, so incredibly resilient, has always recovered (though after long lags) after major extinction spasms, it is only after whatever has caused the extinction event has dissipated. That cause, in the case of the Sixth Extinction, is ourselves — Homo sapiens. This means we can continue on the path to our own extinction, or, preferably, we modify our behavior toward the global ecosystem of which we are still very much a part. The latter must happen before the Sixth Extinction can be declared over, and life can once again rebound.

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