World Population Day Panel Discussion

Scientists Warning Europe – Jul 14, 2021

World Population Day Presentation and Panel Discussion – What is a sustainable population? Why, when and what should we do about it?

This was a high level discussion involving top scientists discussing what is a ‘scientifically defensible, sustainable human population size for the long term’ as called for in the World Scientists Warning to Humanity – A Second Notice issued in 2017 by over 15,000 scientists. Once we know the sustainable population size then how should we get there and when? The 2017 warning also called for ‘rallying nations and leaders to support that vital goal’ in terms of population size.

July 11th is World Population Day. Population is also included as one of the 6 stressors in the World Scientists Warning of Climate Emergency issued on 5 November 2019 .Connected with this Scientists Warning Europe believe the United Nations should include a scientifically determined population goal into its SDGs. This would seem to be currently a worrying weakness in the current list of SDGs as so many of them are, in any case, dependent on or effected by global population levels and connected consumption.

The event was chaired by Ed Gemmell, Managing Director of Scientists Warning Europe. The panellists included the following eminent scientists, who each gave a short talk on the subject before this Panel Discussion, during which they each in turn did their best to answer the tough questions at the beginning!

D Bill Rees
Prof Phoebe Barnard
Dr Christopher Tucker
Dr Jane O’Sullivan

Dr O’Sullivan was unable to answer them live from Australia but sent in her answers:
A scientifically defensible, sustainable human population is so far below the current global population that the question becomes irrelevant. We have no way of knowing the technologies and social organisation that will exist by the time we are approaching a sustainable population, so we can’t know what it is. Because we’re in overshoot, we also have to face the inevitability that we will lose more biodiversity, soil and ecosystem function before we regain sustainability. So the sustainable population will depend on the condition of the biosphere by the time we get there. The more damage done, the lower the sustainable population. But this uncertainty should not be an excuse for inaction: our task is as clear as day – we have to minimise overshoot. Which means we must reverse population growth as soon as possible as well as reducing the ecological impact of each person, and restoring ecosystems wherever possible. Human carrying capacity is a useful concept but can only be quantified in hypothetical scenarios that will never match the real world. To inform good policy, all we need to know about it is that the required direction from here is down.
As to whether the UN should add a scientifically determined population goal into its SDGs? What should this be?
No, the SDGs are targets for 2030, and an optimum population is at least a century away. What they should add is wording that acknowledges that most other goals can’t be achieved unless birth rates are more rapidly reduced. Every country should aim for a fertility rate below 1.5 children per woman, but it would be rash to put a date on that. Such a provocation would probably cause a backlash that would do more harm than good.

Together with this video of the Panel Dscussion, a video of the whole event, as well as a video of each of their talks are also available on this channel.

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