Colliding Worlds 3: Sixth extinction

Wellcome Collection recently hosted Colliding Worlds, an event exploring the extraordinary research of Martin Rees, Astronomer Royal, in the thought-provoking context of a conversation with curator and art critic Hans Ulrich Obrist. From astronomy and ecological disaster to science fiction and advice to young scientists, watch the exchange below. 

We’re also publishing excerpts of the conversations that led to this event in a seven-part series. In our third Colliding Worlds post, Martin answers questions from Hans Ulrich about the risk of a ‘sixth extinction’.

Hans Ulrich Obrist

Now I’ve just been reading over the weekend a new book by Elizabeth Kolbert called The Sixth Extinction: An Unnatural History. She says that over the last half a billion years there have been five mass extinctions on earth when the diversity of life suddenly contracted and she says that what could happen now is actually the sixth extinction, and maybe the most devastating extinction since the asteroid impact that destroyed and wiped out the dinosaurs, so it’s kind of interesting because we talk a lot about climate change and we talk a lot about ecology but maybe the most urgent notion which really makes us more aware of this imminent danger is that notion of extinction so I just wanted to see if you would agree with that and what is your view on extinction.

Martin Rees

Yes indeed. As I said earlier, one class of threats for this century are those stemming from the pressures we as humans are collectively imposing on the planet. There are more of us, and each of us is more demanding in terms of energy and resources; already about 40% of the biomass of the earth is being used directly or indirectly by humans. So humans are very much the dominant species in the biosphere, and we are of course changing the biosphere by causing extinctions. And of course climate change could happen too fast for species to adjust to it and that will be an aggravating factor for extinctions, so certainly the extinctions are a consequence of the impact that we are collectively having on the environment.

Hans Ulrich Obrist

Would you agree with Elizabeth Kolbert that that threat of the sixth extinction, that it could lead to the biggest extinction since the dinosaurs? Martin Well how big it is depends on how humanity controls its development in the coming century. Obviously if global warming became very acute, or if we destroyed entire ecosystems then this may indeed be serious, so certainly this could happen. I wouldn’t want to comment on how likely it is –nor be too alarmist — because the outcome depends on many uncertainties: how humanity’s technology will develop, how the population will evolve after mid-century and many other inponderables.

Martin Rees

Of course one ‘doomsday’ scenario is runaway ecological catastrophe which would lead to mass extinctions — but which scenario actually turns into reality will depend on choices which we and the next one or two generations make.

Be sure to read the rest of the series as they are published.

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