Outposts of Progress
- Green Imperialism: Colonial Expansion, Tropical Island Edens and the Origins of Environmentalism, 1600-1860 by Richard Grove
Cambridge, 540 pp, £45.00, April 1995, ISBN 0 521 40385 5
Environmental history is concerned with the ways in which the production of goods and services has both transformed, and been constrained by, the natural infrastructure on which human survival and economic activity depend. Climate perhaps apart, this infrastructure is only imperfectly visible – at best – to anyone who is not a scientist. Most of it consists of biogeochemical cycles – of carbon, nitrogen, H2O etc – mediated in large measure by plants and micro-organisms that maintain inter alia the atmosphere, the soil and the availability and quality of water. Those causes and effects that are more easily observable are often in practice widely separated from each other by time, space and intermediate links that are not so easy to detect. An example is the ocean plankton Emiliania at times visible as huge ‘blooms’ in the seas, which both stores carbon dioxide – a ‘greenhouse gas’ – in its shell, and emits dimethyl sulphide, which, suitably transformed, provides condensation sites for water vapour and causes clouds to form over the oceans.
More critically, what the natural infrastructure provides is not products or resources, but functions (like photosynthesis or respiration) whose precise pattern is constantly shifting. The ultimate reason why we should value a high level of biodiversity is that a multi-species system which can draw on the capacities of a large range of different organisms is better able to adapt, by forming new patterns, to its own internal evolution, or to environmental shocks and changes (whether natural or anthropogenic), than is one containing only a limited range of organisms. This has been shown to be true, both experimentally and by computer models, for ‘microcosms’ consisting of a limited numbers of species which have been artificially isolated from the rest of the world except for the input of energy (usually sunlight). It is reasonable to assume that this holds also for the macrocosm that we inhabit.
Almost all human economic activity has impinged on this natural infrastructure, most commonly but not invariably injuriously. The environmental historian’s task is to analyse these impacts, and the social, economic, demographic, technical and political processes that led to them, or, more rarely, prevented them. Mismanaged environments could kill even in relatively remote times. The breaking of its dykes by the Yellow River in 1117, at a point where it had built up its bed well above the level of the surrounding countryside, is said to have caused a million deaths. Similar disasters happened a number of times on the North China plain, largely because the river had to carry an increased load of suspended sediment after the vegetation cover had been stripped from its middle reaches to make way for cultivation. In modern times the disruption of the infrastructure has become even more significant. The Wuppertal Institute has shown, for example, that as of 1989, about 30 metric tons of solid material and about 770 tons of water had to be physically displaced from their original location each year, in order to support each inhabitant of West Germany. To these large-scale effects two others must be added. Disruption can be produced by very small quantities of pollutants and new chemicals (such as the CFCs thought to cause the thinning of the ozone layer), and by the removal of a progressively larger area of the earth’s surface from participation in most of the functions of the infrastructure – most obviously by sealing it off through the construction of roads, buildings and so on.