“We can’t make sense of our future until we make sense of our past”, writes Howard Lee in his recent book Your Life as Planet Earth: A new way to understand the story of the Earth, its climate and our origins. The book demonstrates the very considerable sense that science has been able to make of our past. There are clear lessons for us as we forge our future, though whether the political leadership is able to take on board those lessons is moot.
In the first part of the book Lee provides a highly readable account of the turbulent history of the planet in the four and a half billion years of its existence. Geology, climate and the evolution of life are the recurrent themes. He measures this long history against an imagined human life spanning a century. It’s an entertaining and effective way of depicting the enormous spans of time before humans arrive on the planet. On this measure simple life starts in the teens of the centenarian’s life; oxygen arrives during the mid-life crisis; primitive plants and fungi start to colonise land in the late 70s; at 86 complex animals show up; in the 90s four-legged life evolves from fish; at 98 the dinosaurs are extinguished; homo sapiens doesn’t emerge until the 29th December in the final year. And in the few remaining minutes of that last year we have achieved a rapid rise in atmospheric carbon dioxide to levels not seen since the Pliocene, three and a half million years ago.
Our rates and quantities of carbon dioxide generation are rivalling those of the great igneous eruptions which had highly destructive effects on the climate of their times, triggering global warming, ocean anoxic events and mass extinctions. We’re making our presence felt in no uncertain manner, and Lee sees no reason to assume we can avoid the consequences which attended past rapid escalations of carbon dioxide in the atmosphere.
The second half of the book shows how scientists have discovered so much about our past. It’s a fascinating account of the enormous range of techniques and ingenuity by which the progression of events and processes has been discovered. Plate tectonics is a stand-out in geology: “In short, it is geology’s unifying theory.” The evidence for evolution is overwhelming. It has been established in the fossil records and in the genes, anatomy and biochemistry of living things today. We have also come to understand that the evolution of life has been an integral part of the planet’s evolution.
Turning to the evidence for past climates Lee explains the numerous proxies by which past temperatures and carbon dioxide levels can be established and confirmed, along with the accompanying behaviour of the oceans. There are uncertainties of course, and there is more to be discovered, but the overall picture to date is impressive in its detail. Carbon dioxide and temperature have moved in lockstep throughout most of Earth’s history, with the gas being both a driver of and responder to warming. The gauging of carbon dioxide levels through the climate changes of the past is, Lee emphasises, crucial to our understanding of how the planet will respond to the rising levels of today.
Lee’s survey of what has been discovered about past climates covers territory mostly familiar to readers who follow climate science, but it is marked by the completeness of its range and the writer’s ability to make complex matters clear to non-scientists. He has a light touch, but achieves admirable clarity in his explanations.
Alarm is, Lee thinks, an entirely appropriate response to scientists’ projections of Miocene-like or maybe even end-Triassic-like conditions for our grandchildren’s world and beyond. He fervently hopes for some unforeseen cooling feedback “to swoop in like a fairytale hero, saving us from destructive climate change”. But Earth’s past shows no sign of that.
The book is testimony to the high worth of the patient processes of the scientific community. The piecing together of Earth’s past is a triumph of human intelligence. It also obviously carries high import for our future as we keep raising the level of carbon dioxide by continuing to burn fossil fuels.
But if science brings understanding it takes politicians to act on scientific information, and at the end of his book Lee reflects on the complete disregard for science shown by many top political leaders. He writes of “the burden of ignorance in the upper echelons of power”. That spectacle is particularly apparent in America where Lee lives. But while I was settling to write this review I viewed for the second time Alister Barry’s documentary Hot Air screened by Maori Television. Watching the dismal progression of political and business leaders in supposedly well-educated New Zealand scrambling to evade or deny the issue of rising emissions was a depressing experience. All the more while reading yet another clear and compelling explanation of the scientific conclusions which any of those leading figures would be capable of understanding.
Lee ventures reflection on what we must do if we are to pull back from invoking the worst consequences of climate change. In this discussion I thought he surrendered too readily to the notion that decarbonisation of our energy systems within the necessary time frame is too much for us to accomplish. He appears influenced by Roger Pielke on this point. If the message from Earth’s past is allowed to finally break through into the public consciousness we may surprise ourselves by the speed with which we can move. But that’s a very big if.