on 31 May 2009
This is a good text-book-style coverage of climatic changes over the quaternary (from 1.8 million yrs ago to the present), and of the implications for vegetation, wildlife and humans. The authors take account of the controversy over the start of the quaternary (some date it to 2.6 million yrs ago) without coming down either way, and generally try to present an impartial view of the field and its ongoing debates.
The first chapter explains, in historical perspective, the discovery/reconstruction of geological periods in general, the quaternary in particular, and ice ages. The second chapter explains the various kinds of evidence that can be used to reconstruct past climates. This assumes some knowledge of concepts in physical geography. Although there is a glossary at the back, it by no means contains all the specialist terms used. However, you can look up specific words in a dictionary, and otherwise the text is perfectly accessible to the layman. This remains an overview, and, though the detail is reasonably satisfying, there are repeated statements to the effect 'that is beyond the scope of this book'. Therefore, if you want to understand a particular technique or kind of evidence in detail, you will need a specialist text. References for further reading at the end of each chapter provide a starting point in this respect.
The next five chapters contain a narrative of climatic/environmental changes, sub-divided in several ways. First, mid to high latitudes (chap 3) and low latitudes (chap 4) up to the beginning of the holocene (i.e. the last glacial retreat, 11,500 yrs ago). Next, the holocene, covering the world as a whole (chap 5). Then a chapter (6) dedicated to the last century or so, when climatic changes are known from actual meteorological records, and finally a chapter (7) specifically on sea level changes over the entire period. Although this narrative covers the whole earth and the whole quaternary, it is very patchy. This, no doubt, reflects the present state of knowledge. I was hoping for something that would show me, millennium by millennium, a snapshot of the world as a whole. Instead, the authors jump around, focusing on times (e.g. the last glacial maximum) or places (e.g. North American lakes) that have been studied intensively. They also rely on material from the Quaternary Environments Network, which is freely available on the web, and the book's patchiness reflects the patchiness of the QEN site. Nevertheless, the book contains enough extra material to be still a very worthwhile purchase, and I would certainly recommend it. I found it helpful to have something that hangs together as a complete text, to supplement what I could glean from the internet.
The penultimate chapter discusses the implications of past climates for human biological and social evolution. For me, this is a particular area of interest. It is a huge subject, of course, and the chapter is just a taster, but it is a welcome inclusion in the book.
The last chapter describes the numerous mechanisms that have been proposed as causes of climatic change. It is mostly neutral on the merits of different theories, except that the authors seem convinced by the Milankovitch theory of variations in the earth's orbital parameters (which affect insolation) being a fundamental driver and creating cyclical patterns in climate. While they are fair and discuss the problems (e.g. they reference the book 'Weather cycles: real or imaginary?' by W. Burroughs), I was disappointed they did not talk more about climate as a chaotic system with its own dynamic. The authors also seem to endorse that contemporary shibboleth, anthropogenic climate change, and, having brought the subject up, do disappointingly little to expose the complexities of what is treated so superficially in public discourse. That said, their references to the topic are mercifully few.
I have found the book a useful source for my own research. It provides a broad/shallow treatment for the non-specialist, and is an effective starting place for anyone wanting to know about past climates of the last two million years.