developing countries. Simulations based on rates of population growth according
to UN Low Estimates result in a world population about 17% lower in year 2060
as compared with the UN Mid Estimates used in the reference run. The
corresponding reduction in the developing countries (excluding China) would be
about 19.5% from 7.3 to 5.9 billion. The combination of higher GDP/capita
(about 10%) and lower world population produces an estimated 40% fewer
people at risk from hunger in the year 2060 compared with the reference scenario.
Even under the most adverse of the three climate scenarios (UKMO) the
estimated number of people at risk from hunger is some 10% lower that that
estimated for the reference case without any climate change. Increases in world
prices of agricultural products, in particular cereals, under the climate change
scenarios employing the low population growth projection are around 75% of
those using the UN medium estimate.
3 Recently Estimated Effects for Climate Scenarios from Higher
Resolution GCMs with New Socio-economic Projections
Since the mid-1990s the spatial resolution of GCMs has increased and their
simulation of air—ocean interactions and other feedback mechanisms has
improved. This has substantially enhanced the accuracy of their projections of
climate change resulting from greenhouse gas forcing. Many are also transient in
nature and are capable of producing time-dependent scenarios, thus enabling the
evaluation of climate change impacts at several different time horizons throughout
this century.
As the climate models have evolved, becoming ever more complex, many of the
assumptions and models used in the assessment of agro-climatic impacts have
also been revised. This has happened for several reasons; for example, in response
to the developments made by the climate modelling community, or due to
advances in understanding in both the natural and social sciences; and to
dramatic changes in the economic and political structure of many of the world’s
major food producing regions. While it is still generally accepted that, for the
foreseeable future, cereal yields will increase globally every year by nearly 1% due
to technological advances, the latest estimates of the potential benefit of the CO
fertilization effect are much lower than was first thought in the early nineties.
Countering this reduction in adaptive capacity the latest population projections
suggest a slowing down in the growth rate of the global population. Early studies
projected that there would be more than 10 billion people in the world by 2060.
It is now thought that the 10 billion people mark will not be passed until the
M. L. Parry, M. T. J. Livermore, C. Rosenzweig, A. Iglesias and G. Fischer, Stabilisation — a way of
securing future world food supply?, in Stabilisation of Atmospheric Carbon Dioxide: Its Effects on
Climate Change Impacts, Department of the Environment, Transport and the Regions/UK
Meteorological Office, 1999, pp. 18—19.
J. Reilly, W. Baethgen, F. E. Chege, S. C. van de Geijn, Lin Erda, A. Iglesias, G. Kenny, D.
Patterson, J. Rogasik, R. Ro¨ tter, C. Rosenzweig, W. Sombroek and J. Westbrook, Agriculture in a
changing climate: impacts and adaptation, in Changing Climate: Impacts and Response Strategies,
Report of Working Group II of the Intergovernmental Panel on Climate Change, 1996.
R. Darwin and D. Kennedy, Economic effects of CO
fertilization of crops: transforming changes
in yield into changes in supply, Environ. Modeling Assess., 2000, 5, 157—168.
Climate Change, Global Food Supply and Risk of Hunger
123
to UN Low Estimates result in a world population about 17% lower in year 2060
as compared with the UN Mid Estimates used in the reference run. The
corresponding reduction in the developing countries (excluding China) would be
about 19.5% from 7.3 to 5.9 billion. The combination of higher GDP/capita
(about 10%) and lower world population produces an estimated 40% fewer
people at risk from hunger in the year 2060 compared with the reference scenario.
Even under the most adverse of the three climate scenarios (UKMO) the
estimated number of people at risk from hunger is some 10% lower that that
estimated for the reference case without any climate change. Increases in world
prices of agricultural products, in particular cereals, under the climate change
scenarios employing the low population growth projection are around 75% of
those using the UN medium estimate.
3 Recently Estimated Effects for Climate Scenarios from Higher
Resolution GCMs with New Socio-economic Projections
Since the mid-1990s the spatial resolution of GCMs has increased and their
simulation of air—ocean interactions and other feedback mechanisms has
improved. This has substantially enhanced the accuracy of their projections of
climate change resulting from greenhouse gas forcing. Many are also transient in
nature and are capable of producing time-dependent scenarios, thus enabling the
evaluation of climate change impacts at several different time horizons throughout
this century.
As the climate models have evolved, becoming ever more complex, many of the
assumptions and models used in the assessment of agro-climatic impacts have
also been revised. This has happened for several reasons; for example, in response
to the developments made by the climate modelling community, or due to
advances in understanding in both the natural and social sciences; and to
dramatic changes in the economic and political structure of many of the world’s
major food producing regions. While it is still generally accepted that, for the
foreseeable future, cereal yields will increase globally every year by nearly 1% due
to technological advances, the latest estimates of the potential benefit of the CO
fertilization effect are much lower than was first thought in the early nineties.
Countering this reduction in adaptive capacity the latest population projections
suggest a slowing down in the growth rate of the global population. Early studies
projected that there would be more than 10 billion people in the world by 2060.
It is now thought that the 10 billion people mark will not be passed until the
M. L. Parry, M. T. J. Livermore, C. Rosenzweig, A. Iglesias and G. Fischer, Stabilisation — a way of
securing future world food supply?, in Stabilisation of Atmospheric Carbon Dioxide: Its Effects on
Climate Change Impacts, Department of the Environment, Transport and the Regions/UK
Meteorological Office, 1999, pp. 18—19.
J. Reilly, W. Baethgen, F. E. Chege, S. C. van de Geijn, Lin Erda, A. Iglesias, G. Kenny, D.
Patterson, J. Rogasik, R. Ro¨ tter, C. Rosenzweig, W. Sombroek and J. Westbrook, Agriculture in a
changing climate: impacts and adaptation, in Changing Climate: Impacts and Response Strategies,
Report of Working Group II of the Intergovernmental Panel on Climate Change, 1996.
R. Darwin and D. Kennedy, Economic effects of CO
fertilization of crops: transforming changes
in yield into changes in supply, Environ. Modeling Assess., 2000, 5, 157—168.
Climate Change, Global Food Supply and Risk of Hunger
123