Leon Vlieger at The Inquisitive Biologist: This is the fifth instalment in what can unofficially be dubbed the 25 Discoveries series by palaeontologist and geologist Donald R. Prothero. After four previous books on fossils, rocks, dinosaurs, and evolution—I reviewed the last three (mostly) positively—Prothero now turns to palaeoclimatology. A chronology with character, this book takes the reader through 4.5 billion years (Ga) of Earth’s changing climate and its impact on life, while explaining how we know what we know.
This book flows from Prothero’s experience teaching about Earth systems and climate change. After browsing some of the books I have on the subject, I noticed that the structure deviates somewhat from others. Whereas Ruddiman’s Earth’s Climate focuses on the underlying concepts, and Summerhayes’s Paleoclimatology follows a 200-year chronology of the discipline of palaeoclimatology, Prothero’s approach hews much closer to Bender’s primer Paleoclimate in following a strict chronology of Earth’s climate. More than a primer, though, it is generously padded out with relevant material to make for a chunky book.
One consequence of the coursework on which Prothero draws is that he starts with four cosmology- and astronomy-themed chapters that he admits are not strictly about climate, such as the formation of stars, solar systems, and our sun and moon. With the literal substrate of our planet in place, there follows a 4.5-Ga-chronology in 21 chapters. For those who have read other popular works on this topic, there are familiar periods such the Huronian Snowball Earth episodes 2.5–2.2 Ga ago, the ice-age worlds of the Carboniferous 359–299 million years (Ma) ago when elevated oxygen levels allowed insects to grow nightmarishly large and a significant chunk of the world’s fossil fuel reserves were formed, or the proverbial greenhouse of the dinosaurs 145–66 Ma ago (this referencing Prothero’s book on the Cretaceous hothouse climate). But there is also attention for events that have rarely or only recently been discussed in popular works. An example of the former is the Carnian Pluvial episode, a strange 2 Ma interval of high humidity and extreme rainfall 234–232 Ma ago. An example of the latter is the Paleocene-Eocene Thermal Maximum ~55.8 Ma ago when atmospheric carbon dioxide levels and temperatures spiked. There is increasing interest in this interval as a past analogue of what is in store for our near future if humans do not rein in greenhouse gas emissions.
An important goal for Prothero is to explain how we know what we know so that readers understand how the climate works and why it changes. As such, much attention is given to the numerous lines of evidence on which palaeoclimatology draws. The fossils that show Greenland was once carpeted by lush forests while Antarctica was the stomping ground of dinosaurs. The stratigraphical evidence that tells stories of past ice ages by way of dropstones, erratics, and glacial till deposits. The fossil riverbeds in today’s deserts. The cyclical climate patterns revealed by repeating strata with obscure names such as cyclothems and varves. The palaeoclimatological archives contained in deep-sea sediment cores and Arctic ice cores. The numerous lines of evidence for plate tectonics. The geochemical evidence showing past changes in the composition of the atmosphere. The importance of microfossils, etc., etc. Prothero provides plenty of background material for the reader not schooled in geology and palaeontology. The only notable omission here is tree rings that are only mentioned in passing; unfortunate, as the story of dendrochronology is fascinating.
A secondary aim of this book is to show how life and climate have interacted with each other.
More here.
