In 1995, environmentalist Richard Leakey wrote a book called The Sixth Extinction. This accessible pocket book described what many others had said and written 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 large enough to see the loss of large proportions of observable biodiversity. In the last event at the end of the Cretaceous 65 million years ago, 75% of the species were lost. Such events may well have occurred in the 3.8 billion years of microscopic life, but they are more difficult for us to detect.

In April 2011, scientists and world ocean experts met at the University of Oxford in the UK to review information on the state of the world’s oceans. After sifting through the evidence for the impacts and considering their consequences, experts agreed that the oceans were losing oxygen due to warming and acidification. They also decided that these negative changes were on the high end of the predictions and were a major extinction threat to marine organisms.

And his 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 unprecedented rate of regional extinctions of habitat types (for example, mangroves and seagrass meadows), but we now face the loss of marine species and entire marine ecosystems, such as coral reefs, in a single generation.”

These ocean experts are describing the details of the mass extinction event Leaky wrote about.

What is striking is the similarity to mass extinction events of the past. The great extinctions occurred because there was a major change in global conditions, hard hitting entire swaths of biodiversity adapted to the previous status quo. Typically, it is a change in the composition of the atmosphere, a change in energy levels reached or held within the enormous heat sinks of the oceans and atmosphere, or specific forceful events, such as a large meteorite impact. .

Remember that most of the earth is actually molten, held together by gravity and a thin crust. It hits a constricted liquid hard and wobbles for a long time. The volcanic activity witnessed by the dinosaurs that survived the initial attack would have been spectacular.

Despite the dinosaurs, past extinctions 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 raising extinction rates enough to qualify as a mass extinction. This is due to local actions: land clearing, river pollution, and fishing of fish stocks. And of global actions: change the atmospheric composition. The result is the loss of biodiversity in a geological instant. It is as if the earth has been hit by a large piece of space rock.

More biodiversity loss seems inevitable. Our carbon pollution grows, we still clear forests for agriculture, divert water to intensify production on fields we already had, and consume resources as our numbers and wealth grow. The mass extinction event is here and now.

There have been victories. A handful of pioneering conservationists at the start of the industrial revolution laid the groundwork for conservation. Serious effort started in the 1960s has led to most countries having some form of protection for at least some iconic habitats and species.

This effort has focused primarily on the land, because that is where we live. We now have reserves, wildlife corridors, species recovery plans, planning restrictions, land management restrictions, water regulations, paid labor to care for natural areas, and a small army of volunteers actively promoting conservation and The sustainability.

Hopefully these actions will save some of those icons and keep some places wild.

And this is vitally important because 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 ocean habitats to adapt to new conditions. There is hope if action is taken.