Two years ago through a university module, I was introduced to the concepts of biodiversity and conservation biology by Dr. David Bickford, an assistant professor in the Department of Biological Sciences in the National University of Singapore. Throughout the 13 weeks in the classroom and through visits to habitats he spoke of diversity at the genetic, species, and ecosystem levels, interactions and synergies of life on Earth, as well as human impact, and through an interview with him I also found more about his research interest in frogs. “All science begins with observation,” Dr. Bickford liked to say, and on this biological crusade to minimise human impact on the natural world he often railed against the “evil quartet” of habitat destruction, overharvesting, introduced species, and secondary extinctions. And human beings bear great responsibilities.
In this vein, Elizabeth Kolbert’s “The Sixth Extinction: An Unnatural History” was both a reminder and an extension for me: that human beings have been altering biodiversity in unprecedented fashion, and that disappearances of flora and fauna are troubling. Describing this phase as the “Holocene extinction” (since we are in the Holocene geological epoch), the “Anthropocene extinction” (a proposed epoch which begins after the Holocene, taking into account significant human impact), or the “Sixth extinction” (following the “Big Five” mass extinction events marked by dramatic decreases in the amount of life on Earth), Kolbert argued that for the first time a mass extinction is likely to be caused by human beings.
What also makes the book an interesting read is Kolbert’s background in journalism. “The Sixth Extinction: An Unnatural History” is divided into thirteen chapters – each tracking “a species that is in some way emblematic”, she prefaced, and therefore reading like stand-alone articles too – and within each chapter there is a great deal of research, fieldwork, and reporting from the ground. Because of her attention to detail not only do readers feel like they are making the observations or having the conversations, but also intrigued to find out more about the historical contexts. Underlying every chapter is, furthermore, a call to action. In fact I highlighted two personal learning points:
– Ocean acidification – which is a decrease in the pH of oceans as a result of carbon dioxide uptake from the atmosphere – is characterised as climate change’s “equally evil twin”: “No single mechanism explains all the mass extinctions in the record, and yet changes in ocean chemistry seem to be a pretty good predictor. Ocean acidification played a role in at least two of the “Big Five” extinctions and quite possibly it was a major factor in the third.”
– How global trade and travel has exponentially increased the rate of reported invasions, of invasive species: “Species that could not survive an ocean crossing at the bottom of a canoe or in the hold of a whaling ship may easily withstand the same journey in the ballast tank of a modern cargo vessel or the bay of an airplane or in a tourist’s suitcase”.
Kolbert ends on words of caution, even though she does highlight researchers and their endeavours around the world working hard to reverse trends or repair damage. “By disrupting these [biological and geochemical systems on Earth]”, she noted, “we are putting our own survival in danger”. She also quotes Stanford ecologist Paul Ehrlich who said, “In pushing other species to extinction, humanity is busy sawing off the limb on which it perches”. Human beings can still shape their legacies, yet change – I think – will be hard.