Cover Page

CONTENTS

PREFACE TO THE SIXTH EDITION

ACKNOWLEDGMENTS

Part I The Past and Present

1 INTRODUCTION

The development of ideas

The development of human population and stages of cultural development

Hunting and gathering

Humans as cultivators, keepers, and metal workers

Modern industrial and urban civilizations

Guide to reading

2 THE HUMAN IMPACT ON VEGETATION

Introduction

The use of fire

Fires: natural and anthropogenic

The temperatures attained in fires

Some consequences of fire suppression

Some effects of fire on vegetation

The role of grazing

Deforestation

Secondary rain forest

The human role in the creation and maintenance of savanna

The spread of desert vegetation on desert margins

The maquis of the Mediterranean lands

The prairie problem

Post-glacial vegetation change in Britain and Europe

Lowland heaths

Introduction, invasion, and explosion

Air pollution and its effects on plants

Forest decline

Miscellaneous causes of plant decline

The change in genetic and species diversity

Guide to reading

3 HUMAN INFLUENCE ON ANIMALS

Introduction

Domestication of animals

Dispersal and invasion of animals

Human influence on the expansion of animal populations

Causes of animal contractions and declines: pollution

Habitat change and animal decline

Other causes of animal decline

Animal extinctions in prehistoric times

Modern-day extinctions

Guide to reading

4 THE HUMAN IMPACT ON THE SOIL

Introduction

Salinity: natural sources

Human agency and increased salinity

Consequences of salinity

Reclamation of salt-affected lands

Lateritization

Accelerated podzolization and acidification

Soil carbon

Soil structure alteration

Soil drainage and its impact

Soil fertilization

Fires and soil quality

Soil erosion: general considerations

Soil erosion associated with deforestation and agriculture

Soil erosion produced by fire

Soil erosion associated with construction and urbanization

Attempts at soil conservation

Guide to reading

5 THE HUMAN IMPACT ON THE WATERS

Introduction

Deliberate modification of rivers

Urbanization and its effects on river flow

Vegetation modification and its effect on river flow

The human impact on lake levels

Changes in groundwater conditions

Water pollution

Chemical pollution by agriculture and other activities

Deforestation and its effects on water quality

Thermal pollution

Pollution with suspended sediments

Marine pollution

Guide to reading

6 HUMAN AGENCY IN GEOMORPHOLOGY

Introduction

Landforms produced by excavation

Landforms produced by construction and dumping

Accelerated sedimentation

Ground subsidence

Arroyo trenching, gullies, and peat haggs

Accelerated weathering and the tufa decline

Accelerated mass movements

Deliberate modification of channels

Nondeliberate river-channel changes

Reactivation and stabilization of sand dunes

Accelerated coastal erosion

Changing rates of salt marsh accretion

The human impact on seismicity and volcanoes

Guide to reading

7 THE HUMAN IMPACT ON CLIMATE AND THE ATMOSPHERE

World climates

The greenhouse gases

Aerosols

Vegetation and albedo change

Forests, irrigation, and climate

The possible effects of water diversion schemes

Lakes

Urban climates

Urban air pollution

Air pollution: some further effects

Stratospheric ozone depletion

Deliberate climatic modification

Conclusion

Guide to reading

Part II The Future

8 THE FUTURE: INTRODUCTION

Introduction

Changes in the biosphere

Climate and geomorphology

Guide to reading

9 THE FUTURE: COASTAL ENVIRONMENTS

Introduction: rising sea levels

The steric effect

Anthropogenic contributions to sea-level change

Permafrost degradation

Melting of glaciers and sea-level rise

Ice sheets and sea-level rise

The amount of change by 2100

Land subsidence

How fast are sea levels rising?

Coral reefs

Salt marshes and mangrove swamps

River deltas

Estuaries

Cliffed coasts

Sandy beaches

The role of sediment starvation

Conclusions

Guide to reading

10 THE FUTURE: HYDROLOGIC IMPACTS

Introduction

Rainfall intensity

Changes in tropical cyclones

Runoff response

Cold regions

Changes in runoff in the UK

Europe

Other examples

Geomorphologic consequences of hydrologic change

Weathering

Guide to reading

11 THE FUTURE: THE CRYOSPHERE

The nature of the cryosphere

The polar ice sheets

Valley glaciers and small ice caps

Predicted rates of glacier retreat

Sea ice

Permafrost regions

Guide to reading

12 THE FUTURE: DRYLANDS

Introduction

Climate changes in the past

Wind erosion of soils

Dust-storm activity

Sand dunes

Rainfall and runoff

River channels

Lake levels

Sea-level rise and arid-zone coastlines

Salt weathering

Guide to reading

13 CONCLUSION

The power of nonindustrial and pre-industrial civilizations

The proliferation of impacts

Are changes reversible?

The susceptibility to change

Human influence or nature?

Into the unknown

Guide to reading

GLOSSARY

REFERENCES

INDEX

Title Page

PREFACE TO THE SIXTH EDITION

It is now a quarter of a century since the first edition of this book appeared. This period has seen a remarkable transformation in interest in the impact that humans are having on the environment, together with an explosion of knowledge. In this edition, I have made substantial changes to the text, figures, tables, and references, and have tried to provide updated statistical information. The biggest change, however, has been to add four new chapters that explore the ways in which global climate change may have an impact on Earth.

ASG

ACKNOWLEDGMENTS

I am most grateful to Mary Thornbush for her assistance in preparing this sixth edition. I have also benefited greatly from the comments of Stan Trimble, Rob Wilby and Tim Burt on an earlier draft. The publisher and author are grateful for permission to use figures and photographs from the following publications: Anisimov, O. A. ‘Projection of changes in permafrost with global warming’, from Physical geography, 10, 1989; Arnell, N. W. and Reynard, N. S. ‘Monthly runoff by the 2050s under two scenarios for six British catchments’ from M. C. Acreman (ed.), ‘The Hydrology of the UK: a study of change’ (Routledge, London, 2000); Atkinson, B. W. ‘Thunder in south-east England’, ‘Total thunder rain in south-east England’ and ‘Number of days with thunder overhead in south-east England’, from Transactions of the Institute of British Geographers, 44, 1968; Birkeland, P. W. and Larson, E. E. ‘Correlation between quantity of waste water pumped into a deep well and the number of earthquakes near Denver, Colorado’, from Putnam’s geology (Oxford University Press, New York, reprinted by permission of Oxford University Press, 1978); Böckh, A. ‘Variations in the level of Lake Valencia, Venezuela to 1968’, from M. T. Farvar and J. P. Milton (eds), The careless technology (Tom Stacey, London, 1973); Brampton, A. H. ‘A selection of “hard engineering” structures designed to afford coastal protection’, from A. H. Brampton, ‘Cliff conservation and protection: methods and practices to resolve conflicts’, in J. Hooke (ed.), Coastal defence and earth science conservation (Geological Society Publishing House, 1998); Brimblecombe, P. ‘Thunder in south-east England’ and ‘Thunder storms per year in London’, from ‘London air pollution 1500–1900’, Atmospheric environment, 11, 1977; Brimblecombe, P. and Camuffo, D. ‘Decadal means of the freeze–thaw cycles in Central England’, from The effects of air pollution on the built environment (Imperial College Press, London, 2003); Brookes, A. ‘Principal types of adjustment in straightened river channels’, from ‘The distribution and management of channelized streams in Denmark., Regulated rivers, 1, 1987; Brown, A. A. and Davis, K. P. ‘The reduction in area burned per area protected for the USA between 1926 and 1969 as a result of fire-suppression policies’, from Forest fire control and its use, 2nd edn (McGraw-Hill, New York, 1973, reproduced with permission of the McGraw-Hill Companies); Chapin, F. S. and Danell, K. ‘Changes in areas of boreal forest’ from F. S. Chapin, O. E. Sala and E. Huber-Sannwald, Global biodiversity in a changing environment (Springer, New York, 2001); Cochrane, R. ‘The changing state of the vegetation cover in New Zealand’, from E. G. Anderson (ed.), New Zealand in maps (Hodder & Stoughton Educational, London, 1977); Cohen and Rushton, ‘The effect of air quality on plant growth in Leeds, England, 1913’, data from R. Barrass, Biology, food and people (Hodder & Stoughton Educational, London, 1974); Cole, S. ‘A Neolithic chert axe-blade from Denmark, of the type which has been shown to be effective at cutting forest in experimental studies’, from The Neolithic revolution, 5th edn (The British Museum [Natural History], London, 1970); Cooke, R. U. and Reeves, R. W. ‘A model for the formation of arroyos (gullies) in the south-western USA’, from Arroyos and environmental change in the American south-west (Clarendon Press, Oxford, 1976, reprinted with permission of Oxford University Press); Council on Environmental Quality, ‘Changes in water pollution in the Great Lakes of North America’, from 17th (1986) and 22nd (1992) Annual Reports; Darby, H. C. ‘The changing distribution of forest in Central Europe between (a) AD 900 and (b) AD 1900’, from W. L. Thomas (ed.), Man’s role in changing the face of the Earth (University of Chicago Press © The University of Chicago, 1956); Dolan, R., Godfrey, P. J. and Odum, W. E. ‘Crosssections of two barrier islands in North Carolina, USA’, from Man’s impact on the barrier islands of North Carolina, American scientist, 61, 1973; Doughty, R. W. ‘The spread of the English house sparrow in the New World’, from The English sparrow in the American landscape: a paradox in nineteenth century wildlife conservation, Research paper 19, School of Geography, University of Oxford, 1978; Edmonson, W. T. ‘Changes in the state of Lake Washington, USA, associated with levels of untreated sewage from 1933 to 1973’, from W. W. Murdoch (ed.), Environment (Sinauer Associates, Sunderland, 1975); Ehrlich, P. R., Ehrlich, A. H. and Holdren, J. P. ‘The growth of human numbers for the past half million years’, from Ecoscience: population, resources, environment (W. H. Freeman, San Francisco, 1977); Elton, C. S. ‘The spread of the Japanese beetle, Popilla japonica, in the eastern USA’, from The ecology of invasion by plants and animals (Methuen, London, 1958); Fenger, J. ‘Schematic presentation of a typical development of urban air pollution levels’ from Atmospheric environment, 33, 1999; Forman, S. L., Oglesby, R. and Webb, R. S. ‘Summary of dune field activity’ from Global and planetary change, 29, 2001; French, H. M. ‘Projection of changes in permafrost with global warming’ from The periglacial environment (2nd edn) (Longman, Harlow, 1996); Gameson, A. L. H. and Wheeler, A. ‘The average dissolved oxygen content of the River Thames at halftide in the July–September quarter since 1890’, from J. Cairns, K. L. Dickson and E. E. Herricks (eds), Recovery and restoration of damaged ecosystems (University Press of Virginia, Charlottesville, 1977, reprinted with permission of the University Press of Virginia); Gilbert, O. L. ‘Air pollution in north-east England and its impact upon growth area for lichens’, from R. Barrass, Biology, food and people (Hodder & Stoughton Educational, London, 1974); Gorman, M. ‘A set of general design rules for nature reserves based on theories of island biogeography’, from Island ecology (Chapman and Hall Publishers Ltd, London, 1979, copyright with kind permission of Kluwer Academic Publishers); Gorman, M. ‘Some relationships between the size of “islands” and numbers of species’, from Island ecology (Chapman and Hall Publishers Ltd, London, 1979, copyright with kind permission of Kluwer Academic Publishers); Goudie, A. S. ‘A schematic representation of some of the possible influences causing climatic change’, from Environmental change, 3rd edn (Clarendon Press, Oxford, 1992, reprinted by permission of Oxford University Press); Goudie, A. S. ‘The concentration of dust storms in the USA in 1939’, from ‘Dust storms in space and time’, Progress in physical geography, 7, 1983; Goudie, A. S. and Wilkinson, J. C. ‘The Ghyben–Herzberg relationship between fresh and saline ground water and the effect of excessive pumping from the well’, from The warm desert environment (Cambridge University Press, Cambridge, 1977); Green, F. H. W. ‘Annual total area of field drainage by the tile drains in England and Wales’, from Recent changes in land use and treatment, Geographical journal, 142, 1996; Green, F. H. W. ‘Percentages of drained agricultural land in Europe’, from Field drainage in Europe, Geographical journal, 144, 1978; Gregory, K. J. ‘Relation between drainage density and mean annual precipitation’, from E. Derbyshire (ed.), Geomorphology and climate (Chichester: John Wiley and Sons. © 1976); Gupta, H. K. ‘Worldwide distribution of reservoir-triggered changes in seismicity’ from Earth-science reviews, 58, 2002; Haagen-Smit, A. J. ‘Possible reactions involving primary and secondary pollutants’, from R. A. Bryson and J. E. Kutzbach (eds), Air pollution (Commission on College Geography Resource Paper 2. Washington DC: Association of American Geographers); Haggett, P. ‘Land rotation and population density’, from Geography: a modern synthesis, 3rd edn (Prentice-Hall, London, 1979); Haigh, M. J., ‘Some shapes produced by shale tipping’, from Evolution of slopes on artificial landforms – Blaenavon, UK, Research Paper 183, Department of Geography, University of Chicago; Harris, J. M., Oltmans, S. J., Bodeker, G. E., Storlaski, R., Evans, R. D. and Quincy, D. M. ‘Global ozone trends’ from Atmospheric environment, 37, 2003; Hollis, G. E. ‘Some hydrological consequences of urbanization’, from The effects of urbanization on floods of different recurrence intervals, Water resources research, 11, 1975; Hughes, R. J., Sullivan, M. E. and York, D. ‘Rates of erosion in Papua New Guinea in the Holocene derived from rates of sedimentation in Kuk Swamp’, from Human-induced erosion in a highlands catchment in Papua New Guinea: the prehistoric and contemporary records, Zeitschrift für geomorphologie, supplementband, 83, 1991; Johansen, H. E. ‘The spread of contour-strip soil conservation methods in Wisconsin, USA, between 1939 and 1967’, from S. W. Trimble and S. W. Lund (eds), Soil conservation and the reduction of erosion and sediment in the Coon Creek Basin, Wisconsin, US Geological Survey professional paper, 1234, 1982; Judd, W. R. ‘Relationships between reservoir levels and earthquake frequencies’, from Seismic effects of reservoir impounding, Engineering geology, 8, 1974; Keller, E. A. ‘Comparison of the natural channel morphology and hydrology with that of a channelized stream’, from D. R. Coates (ed.), Geomorphology and engineering (Hutchinson and Ross, 1976); Kirby, C. ‘Lead concentration (annual means) in UK sites’ from Geography, 80, 1995; Komar, P. D. ‘Examples of the effects of shoreline installations on beach and shoreline morphology’, from Beach processes and sedimentation (Prentice-Hall, Englewood Cliffs, 1976); Laporte, L. F. ‘Maximum temperatures for the spawning and growth of fish’, from Encounter with the Earth (copyright © by permission of Harper and Row Publishers, Inc., 1975); MacGrimmon, ‘The original area of distribution of the brown trout and areas where it has been artificially naturalized’, from J. Illies (ed.), Introduction to zoogeography (Macmillan, London, 1974); Manshard, W. ‘The irrigated areas in Sind (Pakistan) along the Indus Valley’, from Tropical agriculture (Addison-Wesley-Longman, 1974, © Bibliographisches Institute A. G., Mannheim); McGlone, M. S. and Wilmshurst, J. M. ‘Summary percentage pollen diagram’, from Quaternary international, 59, 1999; Meade, R. H. and Trimble, S. W. ‘The decline in suspended sediment discharge to the eastern seaboard of the USA between 1910 and 1970 as a result of soil conservation measures …’, from Changes in sediment loads in rivers of the Atlantic drainage of the United States since 1900, Publication of the International Association of Hydrological Science, 113, 1974; Mellanby, K. ‘The increase of lichen cover on trees outside the city of Belfast, Northern Ireland (after Fenton)’, from Pesticides and pollution (Fontana, London, 1967); Meybeck, M. ‘Recent trends of nitrate concentration in some rivers’, from B. von Bodungen and R. K. Turner (eds), Science and integrated coastal management (Dahlem University Press, Dahlem, 2001); Midgley, G. F., Hannak, L., Millar, D., Thiuller, W. and Booth, A. ‘Current mapped Fynbos biome’, from Biological conservation, 112, 2003; Nature Conservancy Council, ‘The changing range of the little ringed plover, related to habitat change, especially as a result of the increasing number’ and Trimble, S. W. ‘The decline in suspended sediment discharge to the eastern seaboard of the USA between 1910 and 1970 as a result of soil conservation measures of gravel pits’, from Nature conservation and agriculture (Nature Conservancy Council, Her Majesty’s Stationery Office, London, 1977); Nature Conservancy Council, ‘Losses of lowland heath in southern England’, from Nature conservation in Great Britain (Nature Conservancy Council, Shrewsbury, 1984); Nature Conservancy Council, ‘Reduction in the range of the silver spotted skipper butterfly (Hesperia comma)’, from Nature conservation and agriculture (Nature Conservancy Council, Her Majesty’s Stationery Office, London, 1977); Nature Conservancy Council, ‘Reduction in the range of species related to habitat loss’, from Nature conservation and agriculture (Nature Conservancy Council: Her Majesty’s Stationery Office, London, 1977); Oerlemans, J. ‘Generalised curves of ablation and accumulation’ from R. A. Warwick, E. M. Barrows and T. M. L. Wigley (eds), Climate and sea level change: observations, projections and implications (Cambridge University Press, Cambridge, 1993); Oppenheimer, M. ‘Cross section of an ice stream’ from Nature, 393 (© Macmillan Publishers Ltd, 1998); Parker, A. G., Goudie, A. S., Anderson, D. E., Robinson, M. A. and Bonsall, C. ‘Relations between factors influencing the mid-Holocene elm decline’ from Progress in physical geography, 26, 2002; Pereira, H. C. ‘The increase of water yield after clear-felling a forest: a unique confirmation from the Coweeta catchment in North Carolina’, from Land use and water resources in temperate and tropical climates (Cambridge University Press, Cambridge, 1973); Rapp, A., Le Houerou, H. N. and Lundholm, B. ‘Desert encroachment in the northern Sudan 1958–75, as represented by the position of the boundary between sub-desert scrub and grassland in the desert’, from Ecological bulletin, 24, 1976; Rapp, A. ‘Relation between spacing of wells and over-grazing’, from A review of desertization in Africa – water, vegetation and man (Secretariat for International Ecology, Stockholm, Report no 1, 1974); Roberts, N. ‘The human colonization of Ice-Age earth’, from The Holocene: an environmental history (Blackwell Publishers, Oxford, 1989); Schwartz, M. W., Porter, D. J., Randall, J. M. and Lyons, K. G. ‘Number of non-indigenous plant species by date as reported in botanical treatments of the California flora’, from Sierra Nevada Ecosystems project: final report for Congress Vol. II, Davis: University of California, 1996; Shiklomanov, A. I. ‘Changes in annual runoff in the CIS due to human activity during 1936–2000’, from J. C. Rodda (ed.), Facets of hydrology II (copyright © 1985 John Wiley & Sons, Inc., reprinted by permission of John Wiley & Sons Inc.); Shiklomanov, A. I. ‘Some major schemes proposed for large-scale inter-basin water transfers’, from J. C. Rodda (ed.), Facets of hydrology II (copyright © 1985 John Wiley & Sons, Inc., reprinted by permission of John Wiley & Sons Inc.); Spate, O. H. K. and Learmonth, A. T. A. ‘The Madurai–Ramanthapuram tank country in south India’, from India and Pakistan (Methuen, London, 1967); Spencer, J. E. and Thomas, W. L. ‘The diffusion of mining and smelting in the Old World’, from Introducing cultural geography, 2nd edn (copyright © 1978 John Wiley & Sons, Inc., reprinted by permission of John Wiley & Sons, Inc.); Strandberg, C. H. ‘Biological concentration occurs when relatively indestructible substances (DDT for example) are ingested by lesser organisms at the base of the food pyramid’, from G. H. Smith (ed.), Conservation of natural resources, 4th edn (copyright © 1971 John Wiley & Sons, Inc., reprinted by permission of John Wiley & Sons, Inc.); Titus, J. G. ‘Overwash: natural response of undeveloped barrier islands to sea level rise’ from Coastal management, 18, 1990; Trimble, S. W. ‘Changes in the evolution of fluvial landscapes in the Piedmont of Georgia, USA in response to land-use change between 1700 and 1970’, from Man-induced soil erosion on the southern Piedmont (Soil Conservation Society of America, © Soil Conservation Society of America, 1974); Viles, H. A. ‘Conceptual model of the impact of effective precipitation’ from Journal of nature conservation, 11, 2003; Vinnikov, K. Y. ‘Observed decrease of Northern Hemisphere sea ice extent’ from Science, 286, 1999; US Geological Survey, ‘Historical sediment and water discharge trends for the Colorado river’, H. E. Schwarz, J. Emel, W. J. Dickens, P. Rogers and J. Thompson (eds), ‘Water quality and flows’, from B. L. Turner, W. C. Clark, R. W. Kates, J. F. Richards, J. T. Matthews and W. B. Meyer (eds), The Earth as transformed by human action (Cambridge University Press, Cambridge, 1991); Wallwork, K. L. ‘Subsidence in the salt area of mid-Cheshire, England, in 1954’, from Subsidence in the mid-Cheshire industrial area, Geographical journal, 122, 1956; Watson, A. ‘The distribution of pits and ponds in a portion of north-western England’, from ‘The origin and distribution of closed depressions in south-west Lancashire and north-west Cheshire’, unpublished BA dissertation, University of Oxford; Wilkinson, W. B. and Brassington, F. C. ‘Groundwater levels in the London area’, from R. A. Downing and W. B. Wilkinson (eds), Applied groundwater hydrology – a British perspective (Clarendon Press, Oxford, 1991, by permission of Oxford University Press); Wolfe, S. A. ‘Dune mobility for various stations’ from Journal of arid environments, 36, 1997; Woo, M. K., Lewkowicz, A. G. and Rouse, W. R. ‘Ground settlement in response to a thickening of the active layer’ from Physical geography, 13, 1992; Wooster, W. S. ‘Decrease in the salinity of the Great Bitter Lake, Egypt, resulting from the intrusion of fresher water by way of the Suez Canal’, from The ocean and man, Scientific American, 221, 1969; Ziswiler, V. ‘The former and present distribution of the bison in North America’, from J. Illies (ed.), Introduction of zoogeography (Macmillan, London, 1974); Ziswiler, V. ‘Time series of animal extinctions since the seventeenth century, in relation to the human population increase’, figure (b) from The earth and human affairs (National Academy of Sciences, 1972).

The publisher and author are grateful to the following for permission to use photographs: Frank Lane Picture Agency/B. S. Turner (3.2); NASA (7.4); Telegraph Colour Library (7.3); University of Cambridge, Committee for Aerial Photography (9.1).

Part I

The Past and Present

1

INTRODUCTION

The development of ideas

To what extent have humans transformed their natural environment? This is a crucial question that intrigued the eighteenth century French natural historian, Count Buffon. He can be regarded as the first Western scientist to be concerned directly and intimately with the human impact on the natural environment (Glacken, 1963, 1967). He contrasted the appearance of inhabited and uninhabited lands: the anciently inhabited countries have few woods, lakes or marshes, but they have many heaths and scrub; their mountains are bare, and their soils are less fertile because they lack the organic matter which woods, felled in inhabited countries, supply, and the herbs are browsed. Buffon was also much interested in the domestication of plants and animals – one of the major transformations in nature brought about by human actions.

Studies of the torrents of the French and Austrian Alps, undertaken in the late eighteenth and early nineteenth centuries, deepened immeasurably the realization of human capacity to change the environment. Fabre and Surell studied the flooding, siltation, erosion and division of watercourses brought about by deforestation in the Alps. Similarly de Saussure showed that Alpine lakes had suffered a lowering of water levels in recent times because of deforestation. In Venezuela, von Humboldt concluded that the lake level of Lake Valencia in 1800 (the year of his visit) was lower than it had been in previous times, and that deforestation, the clearing of plains, and the cultivation of indigo were among the causes of the gradual drying up of the basin.

Comparable observations were made by the French rural economist, Boussingault (1845). He returned to Lake Valencia some 25 years after von Humboldt and noted that the lake was actually rising. He described this reversal to political and social upheavals following the granting of independence to the colonies of the erstwhile Spanish Empire. The freeing of slaves had led to a decline in agriculture, a reduction in the application of irrigation water, and the re-establishment of forest.

Boussingault also reported some pertinent hydrological observations that had been made on Ascension Island in the South Atlantic:

 

In the Island of Ascension there was an excellent spring situated at the foot of a mountain originally covered with wood; the spring became scanty and dried up after the trees which covered the mountain had been felled. The loss of the spring was rightly ascribed to the cutting down of the timber. The mountain was therefore planted anew. A few years afterwards the spring reappeared by degrees, and by and by followed with its former abundance. (p. 685)

 

Charles Lyell, in his Principles of geology, one of the most influential of all scientific works, referred to the human impact and recognized that tree felling and drainage of lakes and marshes tended ‘greatly to vary the state of the habitable surface’. Overall, however, he believed that the forces exerted by people were insignificant in comparison with those exerted by nature:

 

If all the nations of the earth should attempt to quarry away the lava which flowed from one eruption of the Icelandic volcanoes in 1783, and the two following years, and should attempt to consign it to the deepest abysses of the ocean they might toil for thousands of years before their task was accomplished. Yet the matter borne down by the Ganges and Burrampooter, in a single year, probably very much exceeds, in weight and volume, the mass of Icelandic lava produced by that great eruption. (Lyell, 1835: 197)

 

Lyell somewhat modified his views in later editions of the Principles (see e.g., Lyell, 1875), largely as a result of his experiences in the USA, where recent deforestation in Georgia and Alabama had produced numerous ravines of impressive size.

One of the most important physical geographers to show concern with our theme was Mary Somerville (1858) (who clearly appreciated the unexpected results that occurred as man ‘dextrously avails himself of the powers of nature to subdue nature’):

 

Man’s necessities and enjoyments have been the cause of great changes in the animal creation, and his destructive propensity of still greater. Animals are intended for our use, and field-sports are advantageous by encouraging a daring and active spirit in young men; but the utter destruction of some races in order to protect those destined for his pleasure, is too selfish, and cruelty is unpardonable: but the ignorant are often cruel. A farmer sees the rook pecking a little of his grain, or digging at the roots of the springing corn, and poisons all his neighbourhood. A few years after he is surprised to find his crop destroyed by grubs. The works of the Creator are nicely balanced, and man cannot infringe his Laws with impunity. (Somerville, 1858: 493)

 

This is in effect a statement of one of the basic laws of ecology: that everything is connected to everything else and that one cannot change just one thing in nature.

Considerable interest in conservation, climatic change and extinctions arose amongst European colonialists who witnessed some of the consequences of westernstyle economic development in tropical lands (Grove, 1997). However, the extent of human influence on the environment was not explored in detail and on the basis of sound data until George Perkins Marsh published Man and nature (1864), in which he dealt with human influence on the woods, the waters and the sands. The following extract illustrates the breadth of his interests and the ramifying connections he identified between human actions and environmental changes:

 

Vast forests have disappeared from mountain spurs and ridges; the vegetable earth accumulated beneath the trees by the decay of leaves and fallen trunks, the soil of the alpine pastures which skirted and indented the woods, and the mould of the upland fields, are washed away; meadows, once fertilized by irrigation, are waste and unproductive, because the cisterns and reservoirs that supplied the ancient canals are broken, or the springs that fed them dried up; rivers famous in history and song have shrunk to humble brooklets; the willows that ornamented and protected the banks of lesser watercourses are gone, and the rivulets have ceased to exist as perennial currents, because the little water that finds its way into their old channels is evaporated by the droughts of summer, or absorbed by the parched earth, before it reaches the lowlands; the beds of the brooks have widened into broad expanses of pebbles and gravel, over which, though in the hot season passed dryshod, in winter sealike torrents thunder, the entrances of navigable streams are obstructed by sandbars, and harbours, once marts of an extensive commerce, are shoaled by the deposits of the rivers at whose mouths they lie; the elevation of the beds of estuaries, and the consequently diminished velocity of the streams which flow into them, have converted thousands of leagues of shallow sea and fertile lowland into unproductive and miasmatic morasses. (Marsh, 1965: 9)

 

More than a third of the book is concerned with ‘the woods’; Marsh does not touch upon important themes such as the modifications of mid-latitude grasslands, and he is much concerned with Western civilization. Nevertheless, employing an eloquent style and copious footnotes, Marsh, the versatile Vermonter, stands as a landmark in the study of environment (Thomas, 1956; Lowenthal, 2000).

Marsh, however, was not totally pessimistic about the future role of humankind or entirely unimpressed by positive human achievements (1965: 43–4):

 

New forests have been planted; inundations of flowing streams restrained by heavy walls of masonry and other constructions; torrents compelled to aid, by depositing the slime with which they are charged, in filling up lowlands, and raising the level of morasses which their own overflows had created; ground submerged by the encroachment of the ocean, or exposed to be covered by its tides, has been rescued from its dominion by diking; swamps and even lakes have been drained, and their beds brought within the domain of agricultural industry; drifting coast dunes have been checked and made productive by plantation; sea and inland waters have been repeopled with fish, and even the sands of the Sahara have been fertilized by artesian fountains. These achievements are far more glorious than the proudest triumphs of war…

 

Reclus (1873), one of the most prominent French geographers of his generation, and an important influence in the USA, also recognized that the ‘action of man may embellish the earth, but it may also disfigure it; according to the manner and social condition of any nation, it contributes either to the degradation or glorification of nature’ (p. 522). He warned rather darkly (p. 523) that ‘in a spot where the country is disfigured, and where all the grace of poetry has disappeared from the landscape, imagination dies out, and the mind is impoverished; a spirit of routine and servility takes possession of the soul, and leads it on to torpor and death’. Reclus (1871) also displayed a concern with the relationship between forests, torrents and sedimentation.

In 1904 Friedrich coined the term ‘Raubwirtschaft’, which can be translated as economic plunder, robber economy or, more simply, devastation. This concept has been extremely influential but is open to criticism. He believed that destructive exploitation of resources leads of necessity to foresight and to improvements, and that after an initial phase of ruthless exploitation and resulting deprivation human measures would, as in the old countries of Europe, result in conservation and improvement. This idea was opposed by Sauer (1938) and Whitaker (1940), the latter pointing out that some soil erosion could well be irreversible (p. 157):

 

It is surely impossible for anyone who is familiar with the eroded loessial lands of northwestern Mississippi, or the burned and scarred rock hills of north central Ontario, to accept so complacently the damage to resources involved in the process of colonization, or to be so certain that resource depletion is but the forerunner of conservation.

 

Nonetheless Friedrich’s concept of robber economy was adopted and modified by the great French geographer, Jean Brunhes, in his Human geography (1920). He recognized the interrelationships involved in anthropogenic environmental change (p. 332): ‘Devastation always brings about, not a catastrophe, but a series of catastrophes, for in nature things are dependent one upon the other.’ Moreover, Brunhes acknowledged that the ‘essential facts’ of human geography included ‘Facts of Plant and Animal Conquest’ and ‘Facts of Destructive Exploitation’. At much the same time other significant studies were made of the same theme. Shaler of Harvard (Man and the earth, 1912) was very much concerned with the destruction of mineral resources (a topic largely neglected by Marsh).

Sauer led an effective campaign against destructive exploitation (Speth, 1977), reintroduced Marsh to a wide public, recognized the ecological virtues of some so-called primitive peoples, concerned himself with the great theme of domestication, concentrated on the landscape changes that resulted from human action, and gave clear and far-sighted warnings about the need for conservation (Sauer, 1938: 494):

 

We have accustomed ourselves to think of ever expanding productive capacity, of ever fresh spaces of the world to be filled with people, of ever new discoveries of kinds and sources of raw materials, of continuous technical progress operating indefinitely to solve problems of supply. We have lived so long in what we have regarded as an expanding world, that we reject in our contemporary theories of economics and of population the realities which contradict such views. Yet our modern expansion has been affected in large measure at the cost of an actual and permanent impoverishment of the world.

 

The theme of the human impact on the environment has, however, been central to some historical geographers studying the evolution of the cultural landscape. The clearing of woodland (Darby, 1956; Williams, 1989, 2003), the domestication process (Sauer, 1952), the draining of marshlands (Williams, 1970), the introduction of alien plants and animals (McKnight, 1959), and the transformation of the landscape of North America (Whitney, 1994) are among some of the recurrent themes of a fine tradition of historical geography.

In 1956, some of these themes were explored in detail in a major symposium volume, Man’s role in changing the face of the earth (Thomas, 1956). Kates et al. (1990: 4) write of it:

 

Man’s role seems at least to have anticipated the ecological movement of the 1960s, although direct links between the two have not been demonstrated. Its dispassionate, academic approach was certainly foreign to the style of the movement … Rather, Man’s role appears to have exerted a much more subtle, and perhaps more lasting, influence as a reflective, broad-ranging and multidimensional work.

 

In the past three decades many geographers have contributed to, and been affected by, the phenomenon which is often called the environmental revolution or the ecological movement. The subject of the human impact on the environment, dealing as it does with such matters as environmental degradation, pollution and desertification, has close links with these developments, and is once again a theme in many textbooks and research monographs in geography (see e.g., Manners and Mikesell, 1974; Wagner, 1974; Cooke and Reeves, 1976; Gregory and Walling, 1979; Simmons, 1979; Tivy and O’Hare, 1981; Turner et al., 1990; Bell and Walker, 1992; Middleton, 1995; Meyer, 1996; Mannion, 1997, 2002).

Concerns about the human impact have become central to many disciplines and to the public, particularly since the early 1970s, when a range of major developments in the literature and in legislation have taken place (Table 1.1). The concepts of global change or global environmental change have developed. These phrases are much used, but seldom rigorously defined. Wide use of the term global change seems to have emerged in the 1970s but in that period was used principally, although by no means invariably, to refer to changes in international social, economic, and political systems (Price, 1989). It included such issues as proliferation of nuclear weapons, population growth, inflation, and matters relating to international insecurity and decreases in the quality of life.

Since the early 1980s the concept of global change has taken on another meaning which is more geocentric in focus. The geocentric meaning of global change can be seen in the development of the International Geosphere–Biosphere Program: a Study of Global Change (IBGP). This was established in 1986 by the International Council of Scientific Unions, ‘to describe and understand the interactive physical, chemical and biological processes that regulate the total Earth system, the unique environment that it provides for life, the changes that are occurring in this system, and the manner in which they are influenced by human activities’.

Table 1.1 Some environmental milestones

1864 George Perkins Marsh, Man and nature
1892 John Muir founds Sierra Club in USA
1935 Establishment of Soil Conservation Service in USA
1956 Man’s role in changing the face of the earth
1961 Establishment of World Wildlife Fund
1962 Rachel Carson’s Silent spring
1969 Friends of the Earth established
1971 Greenpeace established
1971 Ramsar Treaty on International Wetlands
1972 United Nations Environmental Program (UNEP) established
1972 Limits to growth published by Club of Rome
1973 Convention on International Trade in Endangered Species (CITES)
1974 F. S. Rowland and M. Molina warn about CFCs and ozone hole
1975 Worldwatch Institute established
1979 Convention on Long-range Transboundary Air Pollution
1980 IUCN’s (International Union for the Conservation of Nature and Natural Resources) World Conservation Strategy
1985 British Antarctic Survey finds ozone hole over Antarctic
1986 International Geosphere Biosphere Program (IGBP)
1986 Chernobyl nuclear disaster
1987 World Commission on Environment and Development (Brundtland Commission). Our common future
1987 Montreal Protocol on substances that deplete the ozone layer
1988 Intergovernmental Panel on Climate Change (IPCC)
1989 Global Environmental Facility
1992 Earth Summit in Rio and Agenda 21
1993 United Nations Commission on Sustainable Development
1994 United Nations Convention to Combat Desertification
1996 International Human Dimensions Program on Global Environmental Change
1997 Kyoto Protocol on greenhouse gas emissions
2001 Amsterdam Declaration
2002 Johannesburg Earth Summit

The term ‘global environmental change’ has in many senses come to be used synonymously with the more geocentric use of ‘global change’. Its validity and wide currency were recognized when Global environmental change was established in 1990 as

an international journal that addresses the human ecological and public policy dimensions of the environmental processes which are threatening the sustainability of life of Earth. Topics include, but are not limited to, deforestation, desertification, soil degradation, species extinction, sea-level rise, acid precipitation, destruction of the ozone layer, atmospheric warming/cooling, nuclear winter, the emergence of new technological hazards, and the worsening effects of natural disasters.

Figure 1.1 The human colonization of Ice Age Earth (after Roberts, 1989, figure 3.7).

img_0007_0001.gif

In addition to the concept of global change, there is an increasing interest in the manner in which biogeochemical systems interact at a global scale, and an increasing appreciation of the fact that Earth is a single system. Earth system science has emerged in response to this realization (see Steffen et al., 2004).

The huge increase in interest in the study of the human impact on the environment and of global change has not been without its great debates and controversies, and some have argued that environmentalists have overplayed their hand (see e.g., Lomborg’s The skeptical environmentalist, 2001) and have exaggerated the amount of environmental harm that is being caused by human activities. In this book, I take a longterm perspective and seek to show the changes that humankind has caused to a wide spectrum of environmental phenomena.

The development of human population and stages of cultural development

Some six or so million years ago, primitive human precursors or hominids appear in the fossil record (Wood, 2002). However, the first recognizable human, Homo habilis, evolved about 2.4 million years ago, more or less at the time that the ice ages were developing in mid-latitudes. The oldest remains have been found either in sediments from the Rift Valleys of East Africa, or in cave deposits in South Africa. Since that time the human population has spread over virtually the entire land surface of the planet (Oppenheimer, 2003) (Figure 1.1). Homo may have reached Asia by around two million years ago (Larick and Ciochan, 1996) and Europe not much later. In Britain the earliest fossil evidence, from Boxgrove, is from around half a million years ago. Modern humans, Homo sapiens, appeared in Africa around 160,000 years ago (Crow, 2002, Stringer, 2003; White et al., 2003).

Table 1.2 gives data on recent views of the dates for the arrival of humans in selected areas. Some of these dates are controversial, and this is especially true of Australia, where they range from c. 40,000 years to as much as 150,000 years (Kirkpatrick, 1994: 28–30). There is also considerable uncertainty about the dates for humans arriving in the Americas. Many authorities have argued that the first colonizers of North America, equipped with so-called Clovis spears, arrived via the Bering landbridge from Asia around 12,000 years ago. However, some earlier dates exist for South America and these perhaps imply an earlier phase of colonization (Dillehay, 2003).

Table 1.2 Dates of human arrivals

AreaSourceDate (years BP)
AfricaKlein (1983)2,700,000–2,900,000
ChinaHuang et al. (1995)1,900,000
Georgian RepublicGabunia and Vekua (1995)1,600,000–1,800,000
JavaSwisher et al. (1994)1,800,000
EuropeChampion et al. (1984)c. 1,600,000 but most post-350,000
BritainRoberts et al. (1995)c. 500,000
JapanIkawa-Smith (1982)c. 50,000
New GuineaBulmer (1982)c. 50,000
AustraliaBowler et al. (2003)c. 40,000–50,000
North AmericaIrving (1985)15,000–40,000
South AmericaGuidon and Delibrias (1986)32,000
PeruKeefer et al. (1998)12,500–12,700
IrelandEdwards (1985)9000
CaribbeanMorgan and Woods (1986)4500
PolynesiaKirch (1982)2000
MadagascarBattistini and Verin (1972)c. AD 500
New ZealandGreen (1975)AD 700–800

There are at least three interpretations of global population trends over the past two to three million years (Whitmore et al., 1990). The first, described as the ‘arithmetic-exponential’ view, sees the history of the global population as a two-stage phenomenon: the first stage is one of slow growth, while the second stage, related to the industrial revolution, displays a staggering acceleration in growth rates. The second view, described as ‘logarithmic-logistic’, sees the past million years or so in terms of three revolutions – the tool, agricultural and industrial revolutions. In this view, humans have increased the carrying capacity of Earth at least three times. There is also a third view, described as ‘arithmetic-logistic’, which sees the global population history over the past 12,000 years as a set of three cycles: the ‘primary cycle’, the ‘medieval cycle’ and the ‘modernization cycle’; these three alternative models are presented graphically in Figure 1.2.

Estimates of population levels in the early stages of human development are difficult to make with any degree of certainty (Figure 1.3a). Before the agricultural ‘revolution’ some 10,000 years ago, human groups lived by hunting and gathering in parts of the world where this was possible. At that time the world population may have been of the order of five million people (Ehrlich et al., 1977: 182) and large areas would only recently have witnessed human migration. The Americas and Australia, for example, were probably virtually uninhabited until about 11,000 and 40,000 years ago respectively.

The agricultural revolution probably enabled an expansion of the total human population to about 200 million by the time of Christ, and to 500 million by AD 1650. It is since that time, helped by the medical and industrial revolutions and developments in agriculture and colonization of new lands, that human population has exploded, reaching about 1000 million by AD 1850, 2000 million by AD 1930 and 4000 million by AD 1975. The figure had reached over 6000 million by the end of the millennium. Victory over malaria, smallpox, cholera and other diseases has been responsible for marked decreases in death rates throughout the non-industrial world, but death-rate control has not in general been matched by birth control. Thus the annual population growth rate in the late 1980s in South Asia was 2.64%, Africa 2.66% and Latin America (where population increased sixfold between 1850 and 1950) 2.73%. The global annual growth in population over the past decade has been around 80 million people (Figure 1.3b).

The history of the human impact, however, has not been a simple process of increasing change in response to linear population growth over time, for in specific places at specific times there have been periods of reversal in population growth and ecological change as cultures collapsed, wars occurred, disease struck and habitats abandoned. Denevan (1992), for example, has pointed to the decline of native American populations in the new world following European entry into the Americas. This created what was ‘probably the greatest demographic disaster ever’. The overall population of the western hemisphere in 1750 was perhaps less than a third of what it may have been in 1492, and the ecological consequences were legion.

Clearly, this growth of the human population of Earth is in itself likely to be a highly important cause of the transformation of nature. Of no lesser importance, however, has been the growth and development of culture and technology. Sears (1957: 51) has put the power of humankind into the context of other species:

Figure 1.2figure 2.1