consequences will vary from region to region, but the burdens are likely to fall
disproportionately on the poorer populations in low-income countries, and on
those made vulnerable by age or pre-existing illness.
Sea-level rise is another environmental consequence of climate change. Oceans
are thermally expanding and most glaciers are already shrinking in a warmer
world. In consequence, sea level is forecast to rise by approximately 40 cm by
2100. This rate of rise would be several times faster than has occurred over the
past century. This is important, since over half of the world’s population now lives
within 60 km of the sea, and such a rise in sea level could have widespread impacts
on public health, especially in vulnerable populations (e.g. small island states,
coastal Bangladesh and the Nile Delta). A half-metre rise (at today’s population)
would approximately double the number who experience flooding annually from
around 50 million to 100 million. A range of adverse physical and psychological
health consequences would result from population displacement and economic
disruption due to rising sea levels, agroecosystem decline and freshwater shortages.
Sea-level rise would damage coastal structures and arable land; rising seas
would salinate coastal freshwater aquifers, particularly those beneath small
islands. Sea-level rise would also affect sewage and wastewater disposal; and
would influence the local ecology of certain infectious diseases such as malaria
and cholera. Indeed, for cholera it is becoming evident that there is a rich and
complex set of ecological circumstances that influence transmission probabilities.
Research findings suggest, increasingly, that the spread of cholera is facilitated by
warmer coastal and estuarine waters and their associated algal blooms. This
means we must add an ecological dimension to the traditional transmission
model of cholera: person-to-person spread via the direct faecal contamination of
local drinking water is not the entire explanation.
The prospect of climate change and the anticipated range of impacts on food
production, population health and social well being add a new dimension of
urgency to our need to find ways of living sustainably. With respect to food
production, the goal is to improve crop yields while leaving the natural resource
base intact. The main ways in which climate change would affect terrestrial food
production are listed in Table 3.
Scientists have used dynamic crop growth models to simulate the effects of
climate change, in conjunction with increased atmospheric carbon dioxide, on
cereal crop yields (which represent almost two-thirds of world food energy). One
pioneering modelling study estimated the additional number of hungry people
attributable to standard projections of climate change by the year 2060, within a
range of plausible future trajectories of demographic, economic and tradeliberalization processes. The estimate varied, depending on the mix of other
assumptions, between an additional 40 million and 300 million relative to a future
background total of around 600 million hungry people.
Regionally, most of this nutritional adversity would occur in sub-Saharan
L. G. Thompson, T. Yao, E. Mosley-Thompson, M. E. Davis, K. A. Henderson and P.-N. Lin,
Science, 2000, 289, 1916.
M. Pascual, X. Rodo´ , S. P. Ellner, R. R. Colwell and M. J. Bouma, Science, 2000, 289, 1766.
M. Parry, C. Rosenzweig, A. Iglesias, G. Fischer, and M. T. J. Livermore, Global Environ. Change,
1999, 9, S51.
M. J. Ahern and A. J. McMichael
152
disproportionately on the poorer populations in low-income countries, and on
those made vulnerable by age or pre-existing illness.
Sea-level rise is another environmental consequence of climate change. Oceans
are thermally expanding and most glaciers are already shrinking in a warmer
world. In consequence, sea level is forecast to rise by approximately 40 cm by
2100. This rate of rise would be several times faster than has occurred over the
past century. This is important, since over half of the world’s population now lives
within 60 km of the sea, and such a rise in sea level could have widespread impacts
on public health, especially in vulnerable populations (e.g. small island states,
coastal Bangladesh and the Nile Delta). A half-metre rise (at today’s population)
would approximately double the number who experience flooding annually from
around 50 million to 100 million. A range of adverse physical and psychological
health consequences would result from population displacement and economic
disruption due to rising sea levels, agroecosystem decline and freshwater shortages.
Sea-level rise would damage coastal structures and arable land; rising seas
would salinate coastal freshwater aquifers, particularly those beneath small
islands. Sea-level rise would also affect sewage and wastewater disposal; and
would influence the local ecology of certain infectious diseases such as malaria
and cholera. Indeed, for cholera it is becoming evident that there is a rich and
complex set of ecological circumstances that influence transmission probabilities.
Research findings suggest, increasingly, that the spread of cholera is facilitated by
warmer coastal and estuarine waters and their associated algal blooms. This
means we must add an ecological dimension to the traditional transmission
model of cholera: person-to-person spread via the direct faecal contamination of
local drinking water is not the entire explanation.
The prospect of climate change and the anticipated range of impacts on food
production, population health and social well being add a new dimension of
urgency to our need to find ways of living sustainably. With respect to food
production, the goal is to improve crop yields while leaving the natural resource
base intact. The main ways in which climate change would affect terrestrial food
production are listed in Table 3.
Scientists have used dynamic crop growth models to simulate the effects of
climate change, in conjunction with increased atmospheric carbon dioxide, on
cereal crop yields (which represent almost two-thirds of world food energy). One
pioneering modelling study estimated the additional number of hungry people
attributable to standard projections of climate change by the year 2060, within a
range of plausible future trajectories of demographic, economic and tradeliberalization processes. The estimate varied, depending on the mix of other
assumptions, between an additional 40 million and 300 million relative to a future
background total of around 600 million hungry people.
Regionally, most of this nutritional adversity would occur in sub-Saharan
L. G. Thompson, T. Yao, E. Mosley-Thompson, M. E. Davis, K. A. Henderson and P.-N. Lin,
Science, 2000, 289, 1916.
M. Pascual, X. Rodo´ , S. P. Ellner, R. R. Colwell and M. J. Bouma, Science, 2000, 289, 1766.
M. Parry, C. Rosenzweig, A. Iglesias, G. Fischer, and M. T. J. Livermore, Global Environ. Change,
1999, 9, S51.
M. J. Ahern and A. J. McMichael
152