The geological record shows there have been five events where the species of plant and animal have undergone massive declines over a relatively short period.
The most recent was about 50,000,000 years ago and terminated the dinosaurs.
This allowed the few existing mammals to flourish, develop and eventually, and relatively very recently, become human.
The dinosaurs expired because they could not cope with the massive disruption following a strike from a huge asteroid.
Earlier events may have been similar collisions; severe climate change; perhaps the consequence of major, prolonged volcanic activity.
The geological record is in billions of tons of fossil bearing sedimentary rock (sorry creationists).
The sixth great extinction is under way at the moment. It is produced by pollution, change of land use, invasive species, loss of habitat, change of climate.
All the results of our impact on the planet.
We are becoming rapidly more damaging with our unsustainable demand for more resources.
There is a concept in ecology termed: “keystone species” it refers to species in an ecosystem without which there is disruption and eventually species loss.
Classic examples are sea otters; beavers; and often, the predators, at the top of the food chain.
The originator of this concept ,Robert T. Paine, just before he died, modified his theory to include “hyperkeystone species” that totally disrupt ecosystems: That is US.
This is not just happening in South America, or Australia, it is also here on our doorstep. We consume far more than the earth can provide in the long term.
We make materials that will not rot down.
An example close to home: we are even prepared to drive a road, on a huge embankment through a pristine wilderness, the Lough Beg flood plain: Seamus Heaney’s country.
A vanishingly rare area of natural beauty which once vandalised in this dreadful way can never be restored. Please see Wednesday June 28 papers for the latest news on this “road improvement.”
Phil Allen, Carrickfergus