Prophets of a fragile planet

It takes a strong nerve to be a geologist these days. We study a planet with a long and alarmingly turbulent history. We decipher a rock record in which the slowly accumulated products of steady earth processes are punctuated by the debris of catastrophes: volcanic eruptions, earthquakes, hurricanes, climatic changes and mass extinctions. We have learned that the systems that regulate the earth's environment - the thermostat, the air conditioning, the humidifier - strive for equilibrium, but are easily perturbed. We are teaching this earth science in societies that are consuming resources and emitting effluents so fast that they are upsetting the delicate balance that has spawned and nurtured them. It takes a strong nerve to read the warnings for the future written in the rocks of the past.

This view of the earth scientist as the interpreter of a fragile planet is the theme for Living Dangerously. Heinrich Holland and Ulrich Petersen aim to explain how the earth works, in detail suitable for a university student in science or environmental studies. They share the conviction of many other geologists that better political decisions about the balance of resource use and environmental protection would be made by governments and electorates who knew some basic earth science, or more specifically, some earth system science. Earth system science?

Learning earth science in the traditional way could seem tortuous. You might start with the structures of crystal lattices and how they explained the properties of rock-forming minerals. Then you would be equipped to indentify the main rock types and learn what processes might have formed them. A term or two into the course, and one hopes with some motivation left, you might be allowed to ponder the large-scale earth systems that make sense of global geology. One such system is plate tectonics, now taught at an early stage in most university geology courses. But less attention has been given to other earth systems; those which move matter and energy in the atmosphere, hydrosphere and biosphere. Enter earth system science, the holistic view of the planet as a network of global processes. It offers a top-down way of trying to understand the world, the inverse of the reductionist approach of traditional geology teaching. Earth system science is fast becoming a standard recipe for teaching introductory geology, particularly in North America. Indeed, the United States now sports university departments of earth system science.

In proper holistic fashion Living Dangerously begins with the sun, reasoning that it provides 99.98 per cent of the energy reaching the earth surface. The authors then describe the processes of the atmosphere, hydrosphere and biosphere, leaving the solid earth until its more familiar enshrouding components have been explained. Next we are led around the geological cycle, from sediment supply by weathering and erosion to the sediment sink of the oceans and on to deformation and mountain building. Through these chapters, Holland and Ulrich weave the theme of natural resources and their availability: solar power, agriculture and food, soils, fossil fuels. The next three chapters develop this theme, through the origin of magmas and ores, the economics of mineral commodities, and the options for future energy supply. The book concludes with a wide-ranging assessment of global change and the role of humans in aggravating or alleviating it. Living Dangerously is advertised as "innovative and unconventional". So it is compared with traditional geology textbooks. Maybe it was, at the time of its conception. But it already has to compete with earth systems science texts from other publishers, some of them with a more showy format and in a more sophisticated marketing package. Take The Blue Planet: An Introduction to Earth System Science by Brian Skinner and Stephen Porter (Wiley, 1994). This is a strongly designed book with colour graphics, boxed treatments of detailed material, guest essays, chapter summaries, keyword lists, review questions and an impressive array of supporting material: instructor's manuals, study guides, a computerised test bank, slide sets and CD-ROMs. By comparison, Living Dangerously follows the well-tested format of science textbooks, with its sequential text, monochrome graphics, reference lists, appendix of units and glossary of terms. The one concession to the 1990s is the block of colour plates, rather gratuitously bound in the heart of the book. It may be that the average student will prefer the hypertextual feel of The Blue Planet and its like, with their invitation to graze selectively over the material on offer. I feel more at ease with the linear logic of a book meant to be started at the beginning and finished at the end. So indeed may the teachers who choose the set texts for earth system science courses.

The use of any of these books in UK universities depends on whether the system science approach comes to be seen as a better way of teaching geology than the traditional method. There is a well-founded view that, by starting with the big picture of the earth, students may never have the time or motivation to grapple with the fundamental crystal chemistry, fluid mechanics or genetics that they might need at the sharp end of research in earth sciences. I sympathise. However, I see no reason why holistic and reductionist courses should not complement each other within the same geology degree. Perhaps a more important question is the usefulness of teaching how the earth works to students outside the traditional honours geology degree courses: other natural scientists, environmental scientists, or even economists and lawyers. I would argue that this is not just useful, but increasingly vital to society. There will be a continuing need for research geologists but an equally pressing need for more earth-wise decision makers. It does not need a PhD in geology to judge that Sellafield is a less than ideal place to bury nuclear waste, or that minimising global warming means burning less petrol, it needs an appreciation of earth systems on the level of Living Dangerously.

Holland and Ulrich end by asking how we should view the environmental challenges of the next century, on a six-point scale from exuberant Cornucopian optimism to despondent Malthusian pessimism. They rate themselves three points down the scale as cautious optimists, and it is helpful that this mood pervades the book. However their attitude is one point too hopeful for me, and their treatment of, in particular, the threats of global warming and inadequate food supply a shade too complacent. I would be more optimistic if there were more books like Living Dangerously, and more of the lessons of earth system science being learned and acted on.

Nigel Woodcock is lecturer in earthsciences, University of Cambridge.