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Book Review: Climates: past and present

part of the climate system is discussed in some detail, especially with regard to their key role as a sink for carbon, heat exchange and issues related to their incorporation into atmosphere-ocean general circulation models, it is a shame that more space could not have been devoted to the role of thermohaline circulation in controlling the climate. The emphasis of this book is on future climatic change, but it is put into a much longer geological perspective, and the consideration of some of the main internal and external forcing factors for the climate in the near future can readily be applied to changes throughout the Holocene. In addition, the spatial scale of climatic change dealt with in this book is global down to the macroregional, with true regional or local climatic change being excluded due to the deliberate policy of the author to deal with ‘1⁄4arguments and lines of evidence that rest upon fundamental and well-established principle’. A welcome approach taken by the author is to consider the validity of some common assumptions. For example, in Chapter 3 the author outlines the evidence supporting the assumption that emissions of CO2 from anthropogenic sources have caused the recent increase in atmospheric CO2. When sea-level rise is dealt with, the impact of geological compaction of deltaic sediments, groundwater abstraction, tectonic uplift and postglacial rebound are all brought into the equation, in conjunction with thermal expansion of water, the melting of small glaciers and ice caps, and human activity. This consideration of the assumptions extends to the indicators of recent climatic change, in particular global mean temperature, where there is a need to consider those factors that could create a ‘spurious’ warming trend in the record, such as urbanization around the measurement site, while the changes in the height of ship decks and the speed at which ships travel are both considered in terms of the impact they would have on marine air temperature and sea-surface temperature measurements. Records relating to the cryosphere and biosphere, together with global and regional precipitation, provide additional evidence for recent changes in the global climate. Less satisfactory are the treatment of tropical and extratropical cyclones in the historical record. Likewise, the consideration of El Niño events only over the last 30 years is a shame. On a more positive note, the chapter dealing with translating the emissions of greenhouse gases and aerosols into atmospheric concentrations and radiative forcing would be very useful to a reader looking for a straightforward introduction to the various components involved. Overall, this book is a very useful introduction to the science of climatic change, and would easily provide the basis from which the reader could then explore the issues relating to climatic change in more detail.