In 1995 environmentalist Richard Leakey wrote a book called The Sixth Extinction. This accessible paperback described what many others had been saying and writing about in the scientific literature. It was this: that the current phase of human activity on earth is causing the next mass extinction event, the sixth in 450 million years.
These mass extinctions are events big enough to see the loss of large proportions of the observable biodiversity. In the last event at the end of the Cretaceous 65 million years ago, 75% of species were lost. Such events may well have occurred in the 3.8 billion years of microscopic life but are harder for us to detect.
In April 2011 scientists and world experts on oceans met at Oxford University in the UK to review information on the state of the world’s oceans. After sifting the evidence of impacts and considering their consequences the experts agreed that the oceans were losing oxygen due to warming and acidification. They also decided that these negative changes were tracking at the high end of predictions and was a major extinction threat to marine organisms.
And their general conclusion was that:
“…not only are we already experiencing severe declines in many species to the point of commercial extinction in some cases, and an unparalleled rate of regional extinctions of habitat types (eg mangroves and seagrass meadows), but we now face losing marine species and entire marine ecosystems, such as coral reefs, within a single generation.”
These experts on the oceans are describing the details of the mass extinction event that Leaky wrote about.
What is striking is the similarity with the past mass extinction events. Big extinctions happened because there was a major change in global conditions, hitting hard whole swathes of biodiversity adapted to the previous status quo. Usually it’s a shift in the composition of the atmosphere, a change in energy from the levels reaching or retained within the huge heat sinks of the oceans and atmosphere or specific forceful events such as a major meteorite strike.
Remember that most of the earth is actually molten, held together by gravity and a thin crust. Hit a constrained liquid hard and it wobbles for a long time. Volcanic activity witnessed by any dinosaurs who survived the initial strike would have been spectacular.
Dinosaurs notwithstanding, past extinction events were most significant in the oceans. So this warning from the Oxford meeting is very important.
It tells us that the modifications we have made to the environment are pushing extinction rates high enough to qualify as a mass extinction. This is because of local actions: the clearing of land, polluting rivers and fishing out populations of fish. And from global actions: changing the atmospheric composition. The result is biodiversity loss in a geological instant. It is just as though the earth had been hit by a big chunk of space rock.
More biodiversity loss seems inevitable. Our carbon pollution grows, we still clear forests for agriculture, divert water to intensify production on the fields we already had, and consume resources as our numbers and affluence grow. The mass extinction event is here and now.
There have been wins. A handful of pioneer conservationists at the start of the industrial revolution laid the foundations for conservation. Serious effort ignited in the 1960’s has led to most countries having some form of protection for at least some habitat and iconic species.
This effort has focused mostly on the land, for that is where we live. Now we have reserves, wildlife corridors, species recovery plans, planning restrictions, land management restrictions, water regulations, a paid workforce to look after the natural areas and a small army of volunteers actively promoting conservation and sustainability.
Thankfully these actions will save some of those icons and keep a few places wild.
And this is critically important for these places will be islands, or perhaps arks, to provide the raw material for evolution after the mass extinction.
It may also buy some time for the ocean habitats to adapt to the new conditions.There is hope if there is action.