Here’s a look at a recent study by scientists from Australia, the US, Canada, Germany, Panama, Norway and the UK, from Bob Berwyn writing for the Summit County Citizens Voice. Click through and read the whole thing. Here’s an excerpt:
Three of the five largest extinctions of the past 500 million years were associated with global warming and acidification of the oceans — trends which also apply today, the scientists wrote in the journal Trends in Ecology and Evolution.
Other extinctions were driven by loss of oxygen from seawaters, pollution, habitat loss and pressure from human hunting and fishing – or a combination of these factors. “Currently, the Earth is again in a period of increased extinctions and extinction risks, this time mainly caused by human factors,” the scientists wrote. While the data is harder to collect at sea than on land, the evidence points strongly to similar pressures now being felt by sea life as for land animals and plants.”
An extensive search of historical fossil records has established the main causes of previous marine extinctions — and gives some clues as to the risk of a recurrence. “We wanted to understand what had driven past extinctions of sea life and see how much of those conditions prevailed today,” said co-author John Pandolfi, of the ARC Centre of Excellence for Coral Reef Studies and The University of Queensland.
“It is very useful to look back in time – because if you forget your history, you’re liable to repeat it,” said Pandolfi, an authority on the fate of coral reefs in previous mass extinction events.
Marine extinction events vary greatly. In the ‘Great Death’ of the Permian 250 million years ago, for example, an estimated 95 per cent of marine species died out due to a combination of warming, acidification, loss of oxygen and habitat. Scientists have traced the tragedy in the chemistry of ocean sediments laid down at the time, and abrupt loss of many sea animals from the fossil record.