the spread of water hyacinth in eastern Africa’s Lake Victoria, introduced from
Brazil as a decorative plant, has provided a micro-environment for the
proliferation of diarrhoeal disease bacteria and water snails that transmit
schistosomiasis.
Climate Change
The greenhouse effect is a natural phenomenon, ensuring relative stability in
aggregate global temperatures. However, increasing fossil fuel combustion,
especially in high-income industrialized societies over recent decades, along with
continuing and widespread forest clearance, has augmented the greenhouse effect
in the lower atmosphere. This is a clear manifestation of the unprecedented
large-scale environmental changes that humankind is now inducing. Global
climate change poses substantial risks to human health over the coming century,
and arresting this process presents a major challenge to the world community.
Global temperatures have risen over the last one a half centuries, and the
particular pattern of warming suggests that human-induced alteration of
atmospheric composition, mainly from burning fossil fuels, has been an
increasingly prominent cause. Average world temperatures increased over the
last quarter of the 20th century, mostly due to human influence, and weather
patterns in many regions displayed increasing instability in the 1990s. Current
predictions are for a further rise of around 2—3 °C (although one report suggests
a rise of 5.5 °C) within a plausible range of 1.4—5.8 °C over the next century. This
represents a greater rate of change in temperature than at any time in the last
100 000 years, except perhaps at some stages during the sometimes-hectic
transition to the Holocene 10—15 000 years ago.
Climate change would lead to health effects that would encompass direct and
indirect, immediate and delayed effects (see Table 2). Some health outcomes in
some populations would be beneficial. For example, some tropical regions may
become too hot for mosquitoes, and winter cold-snaps would become milder in
temperate-zone countries where death rates typically peak in winter time — but
most of the anticipated health effects would be adverse.
Direct health effects would include changes in mortality and morbidity from an
altered pattern of exposure to thermal extremes, the respiratory health consequences
of increased exposures to photochemical pollutants and aeroallergens, and the
physical hazards of the increased occurrence, in at least some regions, of storms,
floods or droughts. Intensified rainfall, with flooding, can overwhelm urban
wastewater and sewer systems, leading to contamination of drinking water
supplies, and would be most likely to occur in large crowded cities where
P. R. Epstein, H. F. Diaz, S. Elias, G. Grabherr, N. E. Graham, W. J. M. Martens, A. Fenwick, A. K.
Chessmond and M. A. Amin, Bull. World Health Org., 1998, 59, 777.
Intergovernmental Panel on Climate Change, Second Assessment Report. Climate Change 1995
(Vols. I, II, III), Cambridge University Press, Cambridge, 1996.
D. R. Easterling, G. A. Meehl, C. Parmesan, S. A. Changnon, T. R. Karl and L. O. Mearns, Science,
2000, 289, 2068.
P. M. Cox, R. Betts, C. D. Jones, S. A. Spall and I. J. Totterdell, Nature, 2000, 408, 184.
Intergovernmental Panel on Climate Change, Third Assessment Report, Cambridge University
Press, Cambridge, 2001.
M. J. Ahern and A. J. McMichael
150
Brazil as a decorative plant, has provided a micro-environment for the
proliferation of diarrhoeal disease bacteria and water snails that transmit
schistosomiasis.
Climate Change
The greenhouse effect is a natural phenomenon, ensuring relative stability in
aggregate global temperatures. However, increasing fossil fuel combustion,
especially in high-income industrialized societies over recent decades, along with
continuing and widespread forest clearance, has augmented the greenhouse effect
in the lower atmosphere. This is a clear manifestation of the unprecedented
large-scale environmental changes that humankind is now inducing. Global
climate change poses substantial risks to human health over the coming century,
and arresting this process presents a major challenge to the world community.
Global temperatures have risen over the last one a half centuries, and the
particular pattern of warming suggests that human-induced alteration of
atmospheric composition, mainly from burning fossil fuels, has been an
increasingly prominent cause. Average world temperatures increased over the
last quarter of the 20th century, mostly due to human influence, and weather
patterns in many regions displayed increasing instability in the 1990s. Current
predictions are for a further rise of around 2—3 °C (although one report suggests
a rise of 5.5 °C) within a plausible range of 1.4—5.8 °C over the next century. This
represents a greater rate of change in temperature than at any time in the last
100 000 years, except perhaps at some stages during the sometimes-hectic
transition to the Holocene 10—15 000 years ago.
Climate change would lead to health effects that would encompass direct and
indirect, immediate and delayed effects (see Table 2). Some health outcomes in
some populations would be beneficial. For example, some tropical regions may
become too hot for mosquitoes, and winter cold-snaps would become milder in
temperate-zone countries where death rates typically peak in winter time — but
most of the anticipated health effects would be adverse.
Direct health effects would include changes in mortality and morbidity from an
altered pattern of exposure to thermal extremes, the respiratory health consequences
of increased exposures to photochemical pollutants and aeroallergens, and the
physical hazards of the increased occurrence, in at least some regions, of storms,
floods or droughts. Intensified rainfall, with flooding, can overwhelm urban
wastewater and sewer systems, leading to contamination of drinking water
supplies, and would be most likely to occur in large crowded cities where
P. R. Epstein, H. F. Diaz, S. Elias, G. Grabherr, N. E. Graham, W. J. M. Martens, A. Fenwick, A. K.
Chessmond and M. A. Amin, Bull. World Health Org., 1998, 59, 777.
Intergovernmental Panel on Climate Change, Second Assessment Report. Climate Change 1995
(Vols. I, II, III), Cambridge University Press, Cambridge, 1996.
D. R. Easterling, G. A. Meehl, C. Parmesan, S. A. Changnon, T. R. Karl and L. O. Mearns, Science,
2000, 289, 2068.
P. M. Cox, R. Betts, C. D. Jones, S. A. Spall and I. J. Totterdell, Nature, 2000, 408, 184.
Intergovernmental Panel on Climate Change, Third Assessment Report, Cambridge University
Press, Cambridge, 2001.
M. J. Ahern and A. J. McMichael
150