Global Environmental Changes and Human
Health
MICHAE L J. AHERN AND ANTHONY J. McMI CH AEL
1 Introduction
Earth’s biophysical environment is a large and complex system, driven by solar
energy, and is the source of nature’s capital of ‘goods and services’. Human
societies, like all other species, are not only dependent upon, but are inextricably
linked with this complex system. This environment provides the basics for human
survival — air, food and water. It also provides other life-supporting environmental
‘goods’ — for example clothing, shelter and energy — and ‘services’ — maintenance
of the hydrological cycle and uptake of carbon dioxide and production of oxygen
via plant photosynthesis.
Over many millennia, human societies have influenced the ‘carrying capacity’
of their local environment by occupying greater tracts of territory, modifying
local environments and exploiting the local resources. These exploits varied in
scale and intensity, and required a trade-off between increasing human population
density and the potential weakening of the life-supporting capacity of local
environments. In the past two centuries the scale of human impact on the
environment has increased rapidly as human numbers have expanded and as the
material- and energy-intensity of economic activity has increased. Global
economic activity, for example, increased approximately twenty-fold in the last
century, and whilst we remain uncertain of Earth’s human ‘carrying capacity’
demographers expect that aggregate world population, currently at 6.1 billion,
will probably reach around 9 billion by 2050. Depending on subsequent
scenarios, world population should stabilize by the end of the 21st century
somewhere within the range of 7—15 billion.
Concerns over environmental risks to human health were, until recently,
chiefly confined to local issues, such as microbial and chemical water pollution
and urban air pollution. However, regional environmental problems, including
R. Costanza, R. d’Arge, R. de Groot, S. Farber, M. Grasso, B. Hannon, K. Limburg, S. Naeem, R. V.
O’Neill, J. Paruelo, R. G. Raskin, P. Sutton and M. van den Belt, Nature, 1997, 387, 253.
J. E. Cohen, How Many People Can the Earth Support?, Norton, 1995.
J. C. Caldwell, Br. Med. J., 1999, 319, 985.
United Nations Population Division Department of Economic and Social Affairs, World
Population Prospects: the 2000 Revision, United Nations, 2001.
Issues in Environmental Science and Technology, No. 17
Global Environmental Change
© The Royal Society of Chemistry, 2002
139
Health
MICHAE L J. AHERN AND ANTHONY J. McMI CH AEL
1 Introduction
Earth’s biophysical environment is a large and complex system, driven by solar
energy, and is the source of nature’s capital of ‘goods and services’. Human
societies, like all other species, are not only dependent upon, but are inextricably
linked with this complex system. This environment provides the basics for human
survival — air, food and water. It also provides other life-supporting environmental
‘goods’ — for example clothing, shelter and energy — and ‘services’ — maintenance
of the hydrological cycle and uptake of carbon dioxide and production of oxygen
via plant photosynthesis.
Over many millennia, human societies have influenced the ‘carrying capacity’
of their local environment by occupying greater tracts of territory, modifying
local environments and exploiting the local resources. These exploits varied in
scale and intensity, and required a trade-off between increasing human population
density and the potential weakening of the life-supporting capacity of local
environments. In the past two centuries the scale of human impact on the
environment has increased rapidly as human numbers have expanded and as the
material- and energy-intensity of economic activity has increased. Global
economic activity, for example, increased approximately twenty-fold in the last
century, and whilst we remain uncertain of Earth’s human ‘carrying capacity’
demographers expect that aggregate world population, currently at 6.1 billion,
will probably reach around 9 billion by 2050. Depending on subsequent
scenarios, world population should stabilize by the end of the 21st century
somewhere within the range of 7—15 billion.
Concerns over environmental risks to human health were, until recently,
chiefly confined to local issues, such as microbial and chemical water pollution
and urban air pollution. However, regional environmental problems, including
R. Costanza, R. d’Arge, R. de Groot, S. Farber, M. Grasso, B. Hannon, K. Limburg, S. Naeem, R. V.
O’Neill, J. Paruelo, R. G. Raskin, P. Sutton and M. van den Belt, Nature, 1997, 387, 253.
J. E. Cohen, How Many People Can the Earth Support?, Norton, 1995.
J. C. Caldwell, Br. Med. J., 1999, 319, 985.
United Nations Population Division Department of Economic and Social Affairs, World
Population Prospects: the 2000 Revision, United Nations, 2001.
Issues in Environmental Science and Technology, No. 17
Global Environmental Change
© The Royal Society of Chemistry, 2002
139