This lecture looked at 4.6 billion years of geological history, examining mass extinctions, adaptations, climate change and ultimately asking the question, ‘what will kill us all off’!
Leading the session was Professor Matthew Bennett, who is an engaging and inspiring speaker. He stressed that change is a normal part of geological history but it is our ability to adapt to change that is important.
He explained how – in a billion years – there will be no water left on the planet because the earth will be too hot. In five billion years the earth will be consumed by the sun, as it goes into its Red Planet stage. But then Professor Bennett went on to look at factors that are not so far off; that we as human beings are influencing.
Professor Bennett challenged our perceptions of the greenhouse effect, which is largely influenced by the negative portrayal in the media. Early human activity, for example, kept the earth warmer when it would otherwise have cooled, thereby maintaining a period of stability. This is a positive example of the greenhouse effect.
The current risk is very real though. The oceans will ultimately turn acidic, causing mass marine death and fewer people. Professor Bennett described this as “the dark side of our own making”. He said the greenhouse cause would not destroy humans completely as we are too diverse, geographically distributed and adaptable. It would, however, lead to starvation, disease, social instability and a huge number of deaths.
Professor Bennett explained that we are entering the sixth mass extinction, but that extinction is a natural earth process, which helps maintain biodiversity. It can be seen as wiping the slate clean, ready for a new environment where new species adapt.
He went through possible causes for human extinction, including nuclear or biological warfare; pandemic (likely to be man-made to cause complete destruction); loss of water in a billion years; an ‘impact’ event like that which wiped out the dinosaurs (this would kill billions but not wipe out humans completely); gamma ray burst. He concluded that ultimately human extinction would be by multiple causes, much like the dinosaurs who were already in a weakened state when the asteroid hit.
Professor Bennett concluded that “adapting to change is the most important thing”. We won’t live to see his prediction that, in 300-400 years’ time, human bone mass would increase to cope with rising obesity. Our grandchildren, however, will see more starvation, disease and social instability that is an inevitable consequence of the accelerated greenhouse effect. And will humans be able to adapt behaviourally and physically to prevent that?
An audience discussion followed, particularly centring on the fair and ethical distribution of the world’s resources. There was clearly a lot of passion and high feelings on this topic, unleashed by Professor Bennett’s compelling and engaging delivery of this excellent talk.