Elizabeth Kolbert, journalist and author, has travelled and talked extensively to experts and scientists in the field of conservation to gather the story she presents. She explains the five mass extinctions that have occurred in Earth's long history, together with the fossil and wider geological evidence for them.
With the exception of the asteroid collision with Earth that killed off the dinosaurs and indeed most of life on the planet, extinctions in the past have proceeded relatively slowly, such as the ice ages. This is the salient point in her thesis.
She details in separate chapters the field evidence that is causing concern, for example the rapid disappearance of amphibians worldwide, to the increasing acidity of oceans with multiple effects on food chains and marine life, and the loss of forest, together with the increasing loss of diversity in forests and in plant life worldwide.
Humans are recognised as an invasive species, from earliest times, with, for example, the good evidence of their arrival in North America being coincidental with the total disappearance of the mammoth and other large prey species. The growth of international travel has led to the mass movements of plant and animal species to new homes where they may prey upon, or grow more strongly than natives, and take over.
But the point that really impresses is the significant current speed of the changes taking place, which gives native species or those organisms experiencing environmental change and stress insufficient time to evolve new characteristics and survive, much as the asteroid collision must have done.
This is not yet another depressing book about the use of fossil fuels etc, not that that is unimportant. There is an excellent index and reference list. This is an important book for all who have any concern about our effects on the natural world as a whole in the form that we know, love and treasure it, as well as our own survival.
- Margaret Bannister is a retired Dunedin psychotherapist and science teacher.
