At first blush, you might think this book is part of the ongoing craze of spiritual mindfulness books. But let me refrain from snarky comments. Geologist Marcia Bjornerud does indeed want to instil a sense of mindfulness about deep time, but one that is, pardon the pun, grounded in geology. In her opinion, most of us lack an awareness of durations of important chapters in our planet’s history and of rates of change of many natural processes. As a consequence, we fail to see just how rapidly we are altering our planet. In one of the first paragraphs she eloquently writes:
“Like inexperienced but overconfident drivers, we accelerate into landscapes and ecosystems with no sense of their long-established traffic patterns, and then react with surprise and indignation when we face the penalties for ignoring natural laws”.
And with that, she had me hooked.
Bjornerud assumes little geological background knowledge on behalf of her readers and uses the first two-thirds of the book to give a canned history of relevant discoveries, including: past estimates of Earth’s age and the conceptualisation of deep time (cf. Four Revolutions in the Earth Sciences: From Heresy to Truth), the use of isotopes to date rocks (cf. Nature’s Clocks: How Scientists Measure the Age of Almost Everything), past climates as reconstructed from ice cores (cf. The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change and Our Future), the basics of geomagnetic reversals, spreading mid-ocean ridges, and plate tectonics (cf. The Spinning Magnet: The Force That Created the Modern World – and Could Destroy It and The Tectonic Plates are Moving!), the deep history of earth’s atmosphere and the increase in oxygen (cf. Oxygen: A Four Billion Year History and Oxygen: The Molecule that Made the World), and a short section on mass extinctions (cf. The Ends of the World: Volcanic Apocalypses, Lethal Oceans and Our Quest to Understand Earth’s Past Mass Extinctions). From the above, you can see that many of these topics have been discussed at length in other books, quite a few of which I have reviewed recently on this blog.
The last two chapters are where Bjornerud tries to tie this all together. She introduces the concept of the Anthropocene, and how geologists define this by pointing out that humans are now a geologic force unto themselves. Processes like erosion and sedimentation, sea-level rise, and extinction are happening – and ocean acidity and atmospheric carbon dioxide are changing – at rates many times the background rates of recent millennia (cf. The Anthropocene as a Geological Time Unit).
“the immensity of deep time: all of our recorded history has occurred in a single climatically relatively stable interglacial period”
If there is one observation that never fails to impress upon me the immensity of deep time, it is the following: ice core studies have revealed how all of our recorded history, all roughly ten-thousand years of it, has occurred in a climatically relatively stable interglacial period (a period between ice ages). These same studies have also shown that during the last 2.6 million years, known as the Pleistocene, there have been 30 (!) such changes between ice ages and interglacial periods.
To see a world where carbon dioxide levels are comparable to what is expected in the near future if emissions are not curbed, we have to go back 55 million years, to the Paleocene-Eocene Thermal Maximum (or PETM for short). This section allows Bjornerud to introduce positive feedback loops and the lurking danger of methane currently frozen in permafrost and underwater deposits known as clathrates (cf. The Oceans: A Deep History and Brave New Arctic: The Untold Story of the Melting North). She also shortly dwells on technological solutions such as carbon capture and storage (CCS for short) and geo-engineering (cf. The Planet Remade: How Geoengineering Could Change the World), finding fault with both.
The final chapter is where she tries to convince the reader that thinking like a geologist can save the world. I admit that I came away with mixed feelings. Some of her suggestions border on the spiritual – a brief excursion into how e.g. Buddhism or Norse mythology treat the concept of time and connect to it. Some seem gimmicky – conceptual art that plays with time such as Daniel Hillis’s 10,000 year clock or the ongoing 639-year performance of a John Cage composition. Others are great – pointing out the short-sightedness ingrained in democratic election cycles and the need for long-view leadership. Examples of the last are the native American idea of basing decision making on its likely effects on unborn generations (the Seventh Generation principle) or Kurt Vonnegut’s call for a governmental Department of the Future that represents future generations. Bjornerud envisions geology becoming a far more important part of school curricula, instilling a better conception of deep time in pupils.
“[…] humans are now a geologic force unto themselves.”
To my surprise, I finished this book feeling ever so mildly unsatisfied. I do not think this book deserves a negative judgement though, so let me try and be more specific. First, I am probably not the prime target audience for it – given the canned history she provides, my impression is that Bjornerud is aiming at an audience with little to no knowledge of geology. I have been reading up on many of these topics lately, so a lot of it was not new to me. Second, based on the announcements, I had perhaps unreasonably high expectations, and I felt she could have made more of some of the material on mixing times, rates of Earth phenomena, and length of certain geological cycles that she now relegates to an appendix. Third and final, what about overpopulation? (cf. Should We Control World Population? – sorry if I sound like a stuck record). If you point out the incredible acceleration in increasing carbon dioxide levels in recent decades, why not ask why this happened? (My answer: a burgeoning population that is increasingly affluent. I am sure we could all have our cake and eat it if there were not so many diners). Although unregulated population expansion is also a form of short-sightedness, this has little to do with geology. So, although I like to think Bjornerud has thought about overpopulation, leaving it out of this book is perfectly understandable.
I would urge potential readers not to let above personal considerations discourage too much. The take-home message is that Bjornerud writes extremely well and I found the book a thoroughly captivating and enjoyable read. If you lack geologic background knowledge, many of the concepts presented here will no doubt astound you and help you conceptualise deep time better. I admit that even I picked up new bits of information. The book also has some very handsome, hand-drawn illustrations by Haley Hagerman that help out. Bjornerud is on form when she castigates humanity for its short-sightedness, and her plea for a more time-literate society is convincing. Many geologic biographies of our planet have been written, but Bjornerud here presents a unique take on this genre.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
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