When one considers the concept of carrying capacity in the context of
human population increases, one question immediately arises: What is the
total carrying capacity of the Earth? Will the Earth be able to sustain a
steady-state world population of more than 11 billion people after 2100,
nearly double the current world population?
Answering the question requires considering the spatial distribution of
both people and resources. Where will these 11 or so billion people be
located, and how well aligned will the populations be with essential
resources? Another issue that complicates any analysis of regional or world
carrying capacity is the ability to share or transfer resources effectively.
All great modern cities now operate through a worldwide supply network.
Countries like Japan and the United Kingdom thrive at a very high
standard of living while providing only a small portion of consumed natural
resources from within their geographic boundaries. Further, no assurance
exists that this transfer process can be sustained over time.
Models provide a way to explore how resource limitation can affect
human population and vice versa. For example, Groot et al. (1998) examined food-supply capacity at the global scale using a spatially explicit
model based on data for soils, climate, agronomy, and demography. Use of
the model allows decision makers to explore scenarios of food sufficiency
by region and to determine major sources of uncertainty in projections.
Furthermore, models offer a means to evaluate threats to food security, such
as environmental degradation, economic growth, population explosion, and
climate change (Norse 1994). As one example, a model analysis has shown
that deficiencies in pollinator abundance, diversity, and availability can
have critical impacts on world food supply, security, and trade (Kevan and
Phillips 2001). Similarly, model analysis shows how food consumption
and trade can be influenced by the threat of mad cow disease in Europe
(Latouche et al. 2000) and Cassava mosaic virus in East Africa (Legg and
Thresh 2000).
15.2.2 Global Climate Change
Strong evidence exists that global climate change in the form of global
warming caused by anthropogenic activity is occurring (IPPC 2001;
Houghton 1994). Driving global climate change is a series of interwoven
phenomena including, but not limited to, deforestation, burning of fossil
fuels, and industrial pollution.Assessing each of these factors independently
in a static model is within our scientific capability today but does not yield
realistic results. Each activity occurs independently at different rates and
concurrently with the natural variability in weather.
The rate of temperature change within the dynamics of greenhouse gas
behavior and natural climate processes is a key area of uncertainty in
the global warming debate. Several complex computer models of climate
change have been developed and are being continually updated, but each
has proven to have strengths and weaknesses in describing actual condi292
Wendell Chris King and Virginia H. Dale
human population increases, one question immediately arises: What is the
total carrying capacity of the Earth? Will the Earth be able to sustain a
steady-state world population of more than 11 billion people after 2100,
nearly double the current world population?
Answering the question requires considering the spatial distribution of
both people and resources. Where will these 11 or so billion people be
located, and how well aligned will the populations be with essential
resources? Another issue that complicates any analysis of regional or world
carrying capacity is the ability to share or transfer resources effectively.
All great modern cities now operate through a worldwide supply network.
Countries like Japan and the United Kingdom thrive at a very high
standard of living while providing only a small portion of consumed natural
resources from within their geographic boundaries. Further, no assurance
exists that this transfer process can be sustained over time.
Models provide a way to explore how resource limitation can affect
human population and vice versa. For example, Groot et al. (1998) examined food-supply capacity at the global scale using a spatially explicit
model based on data for soils, climate, agronomy, and demography. Use of
the model allows decision makers to explore scenarios of food sufficiency
by region and to determine major sources of uncertainty in projections.
Furthermore, models offer a means to evaluate threats to food security, such
as environmental degradation, economic growth, population explosion, and
climate change (Norse 1994). As one example, a model analysis has shown
that deficiencies in pollinator abundance, diversity, and availability can
have critical impacts on world food supply, security, and trade (Kevan and
Phillips 2001). Similarly, model analysis shows how food consumption
and trade can be influenced by the threat of mad cow disease in Europe
(Latouche et al. 2000) and Cassava mosaic virus in East Africa (Legg and
Thresh 2000).
15.2.2 Global Climate Change
Strong evidence exists that global climate change in the form of global
warming caused by anthropogenic activity is occurring (IPPC 2001;
Houghton 1994). Driving global climate change is a series of interwoven
phenomena including, but not limited to, deforestation, burning of fossil
fuels, and industrial pollution.Assessing each of these factors independently
in a static model is within our scientific capability today but does not yield
realistic results. Each activity occurs independently at different rates and
concurrently with the natural variability in weather.
The rate of temperature change within the dynamics of greenhouse gas
behavior and natural climate processes is a key area of uncertainty in
the global warming debate. Several complex computer models of climate
change have been developed and are being continually updated, but each
has proven to have strengths and weaknesses in describing actual condi292
Wendell Chris King and Virginia H. Dale