Home William Rees: What’s Driving The Planet’s Accelerating Species Collapse?

William Rees: What’s Driving The Planet’s Accelerating Species Collapse?

user profile picture Adam Taggart Nov 15, 2017
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The data regarding planetary species loss just gets more alarming.

Today's podcast guest is bioecologist and ecological economist Dr. William Rees, professor emeritus of the University of British Columbia’s School of Community and Regional Planning. Rees is best known for his development of the "ecological footprint" concept as a way to measure the demand a particular population places on the environmental resources it needs to survive.

Since the beginning of modern agriculture (around 1800), human activity has increased demand on planetary resources at an exponential rate. More energy has been expended — and more resources consumed — in the past 40 years than in all of human existence beforehand. That is placing a greater and greater strain on ecosystems that are now dangerously depleted:

At the dawn of agriculture, just ten thousand years ago, human beings accounted for less than 1% of the total mammalian biomass on the planet. Today, there’s been a sevenfold increase, roughly speaking, in the biomass of vertebra species on the planet — but most of that is human-induced. Today, human beings account for about 32 – 35%of the total biomass of mammals, a much greater biomass than at the dawn of agriculture. But when we throw in our domesticated animals and our pets, humans and their domesticated animals amount to 98.5% of the total weight of mammals on planet Earth.

So we’re engaged here, through sheer growth, in the scale of the human enterprise in what ecologists refer to as "competitive displacement". This is a finite planet. There’s a finite flow, a limited flow, of photosynthetic energy through the planet which we share with millions of other species. Now, on a finite planet with limited energy flow, the more any one species takes the less is available for everything else. So as humans have gone from less than 1% of the total biomass to over 98.5% of an increased biomass, it means that almost all other species with which we share that photosynthetic flow have been pushed off the planet.

So we’ve gone from millions to a few thousand elephants. We’ve gone from hundreds of thousands, maybe even millions, of tigers to a handful. And so on. Wildlife on the planet today is clinging to the edges of existence. They may not have gone extinct, but their populations have been reduced to a tiny fraction — a few percent at best — of what used to be.

North America used to have 40 to 60 million bison regularly migrating north and south through our great plains. Well, today there’s only a few thousand bison on domesticated farms or in a couple of parks — they’ve been replaced utterly by the food crops that we grow to feed humans or to support our domestic animals.

Competitive displacement has revealed humans to be the fiercest competitors on Earth for the planet’s living resources, forcing nearly all other species to essentially disappear. 

Click the play button below to listen to Chris' interview with Dr. William Rees (65m:45s).



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