Of all the planets in the universe that could in theory support life, we’ve so far found none even remotely as benevolent as Earth. Our planet delivers perfect “Goldilocks” conditions – not too much and not too little of all the things life requires. But it’s no coincidence. If Earth seems tailor-made for us, it’s because life itself made it so.
This is the central and convincing argument US climate scientist Michael Mann makes in Our Fragile Moment. As he explores periods in Earth’s deep past to illustrate how interdependent our planet’s climate history and life’s evolution are, the fragility of our current predicament becomes undeniable.
Anyone who has come across the term Anthropocene will know that the past 10,000 or so years of relatively stable climate conditions have allowed us to develop agriculture and become “civilised”. But Mann extends this idea of mutual influences between climate and evolution right back to Earth’s beginnings some 4.5 billion years ago, when our particular home rock formed from a mix of elements that would, eventually, allow life to spark. The narrative then moves through the planet’s extremes, from icehouse to hothouse, from an atmosphere of vapours toxic to anything but microbes to a protective layer that makes Earth habitable for us.
Along the way, Mann explains the events and introduces the creatures that changed our planet for better or worse, eventually leading to the evolution of a bipedal naked ape.
The single-celled organisms known as cyanobacteria are perhaps the best-known example of prehistoric planetary remakers. They were the first to practise photosynthesis, about 3.5 billion years ago, and began filling Earth’s atmosphere with an unwanted by-product: oxygen. We wouldn’t be here without them.
Mann’s journey through our past is not a scenic tour. Many of early Earth’s major changes were destructive – tectonic plates pushing up mountain ranges and massive volcanic eruptions suffocating landscapes – and he also stops to take a closer look at periods when climate and evolution collided to trigger mass extinctions.
Even the dinosaurs, whose demise was triggered by the arrival of a massive extraterrestrial rock, did not (almost) die out because of the asteroid impact itself. They perished because the collision produced clouds of debris so large they darkened the sky and cooled the climate. Only small creatures, including the earliest mammals and the tiniest feathered dinosaurs that eventually became birds, could hide and survive.
Dinosaurs have a lesson for us, Mann writes. “They didn’t see the asteroid coming. They had no agency and couldn’t do anything about it. We don’t have that excuse.”
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A distinguished professor of atmospheric science at Penn State University, Mann is among the most visible and outspoken climate scientists today. He came to public attention 25 years ago, when he published a graph to show changes in global average temperatures across the past 1000-2000 years. At the time, this “hockey stick” figure earned him praise and scorn. But despite ongoing attacks by climate deniers (see his 2021 book The New Climate War), he remained the go-to scientist to advocate for a liveable future.
He is also among the best writers about climate change, taking readers along easily as he explains some of the denser aspects of climate science, including the complex but hopeful process of how a disrupted Earth returns to a state of equilibrium. The culmination of his journey through Earth’s history is clear: there is no analogue in the past for the rate of warming we’re causing today with our massive extraction of fossil fuels. We’re burning through them a million times faster than they formed.
Perhaps above all, Mann has watched the politics of climate change for long enough to know that “the greatest threat to meaningful climate action today is no longer denial, but despair and doomism, premised on the flawed notion that it is too late to do anything”.