can expect to have between 55 and 65 million extra people at risk of hunger by the
2080s.
The story of how we have arrived at this conclusion is traced below. We outline
the research method, its testing and the first evaluation of effects on food supply
with those climate change scenarios available in the early 1990s. This is followed
by an assessment of effects under some of the most recent scenarios developed for
the Intergovernmental Panel on Climate Change (IPCC). Finally, we consider
the effects of various mitigation strategies, involving stabilization of CO
concentrations, on reducing the scale of impact.
2 Initial Estimations for Climate Scenarios from Low Resolution
Climate Models
The first studies of effects on global food supply, at least those that were
model-based, were published in the early 1990s and were dependent at that
time on climate scenarios that were the product of low resolution global
climate models, before there was an effectively modelled coupling of
ocean—atmosphere interactions. But the general conclusions of that work
still hold today: that climate change is likely to reduce global food potential
and that risk of hunger will increase in the most marginalized economies. In
the study two main components were considered:
1. The estimation of potential changes in crop yield. Potential changes in
national grain crop yields were estimated using crop models and a decision
support system developed by the US Agency for International Development’s
International Benchmark Sites Network for Agrotechnology Transfer
(IBSNAT). The crops modelled were wheat, rice, maize and soybean. These
crops account for more than 85% of the world’s traded grains and legumes.
The estimated yield changes for 18 countries were interpolated to provide
estimates of yield changes for all regions of the world and for all major crops,
by reference to all available published and unpublished information.
2. Estimation of world food trade responses. The yield changes were used as
inputs into a world food trade model, The Basic Linked System (BLS)
developed at the International Institute for Applied Systems Analysis
M. L. Parry, C. Rosenzweig, A. Iglesias, G. Fischer and M. T. J. Livermore, Climate change and
world food security: a new assessment, in M. L. Parry and M. T. J. Livermore (eds.), A new
assessment of the global effects of climate change, Global Environ. Change, 1999, 9 (Supplemental
Issue), s52—s67.
IPCC, R. T. Watson, M. C. Zinyowera and R. H. Moss (eds.), Climate Change 1995: Impacts,
Adaptations and Mitigation of Climate Change: Scientific-Technical Analyses — Contribution of
Working Group II to the Second Assessment Report of the Intergovernmental Panel on Climate
Change, Cambridge University Press, Cambridge, 1995.
C. Rosenzweig and M. L. Parry, Potential impacts of climate change on world food supply. Nature,
1994, 367, 133—138.
International Benchmark Sites Network for Agrotechnology Transfer (IBSNAT), Decision Support
System for Agrotechnology Transfer Version 2.1 (DSSAT V2.1). Dept. Agron. & Soil Sci. College
Trop. Agric. And Hum. Resources. Univ. Hawaii, Honolulu, 1989.
M. Parry and M. Livermore
110
2080s.
The story of how we have arrived at this conclusion is traced below. We outline
the research method, its testing and the first evaluation of effects on food supply
with those climate change scenarios available in the early 1990s. This is followed
by an assessment of effects under some of the most recent scenarios developed for
the Intergovernmental Panel on Climate Change (IPCC). Finally, we consider
the effects of various mitigation strategies, involving stabilization of CO
concentrations, on reducing the scale of impact.
2 Initial Estimations for Climate Scenarios from Low Resolution
Climate Models
The first studies of effects on global food supply, at least those that were
model-based, were published in the early 1990s and were dependent at that
time on climate scenarios that were the product of low resolution global
climate models, before there was an effectively modelled coupling of
ocean—atmosphere interactions. But the general conclusions of that work
still hold today: that climate change is likely to reduce global food potential
and that risk of hunger will increase in the most marginalized economies. In
the study two main components were considered:
1. The estimation of potential changes in crop yield. Potential changes in
national grain crop yields were estimated using crop models and a decision
support system developed by the US Agency for International Development’s
International Benchmark Sites Network for Agrotechnology Transfer
(IBSNAT). The crops modelled were wheat, rice, maize and soybean. These
crops account for more than 85% of the world’s traded grains and legumes.
The estimated yield changes for 18 countries were interpolated to provide
estimates of yield changes for all regions of the world and for all major crops,
by reference to all available published and unpublished information.
2. Estimation of world food trade responses. The yield changes were used as
inputs into a world food trade model, The Basic Linked System (BLS)
developed at the International Institute for Applied Systems Analysis
M. L. Parry, C. Rosenzweig, A. Iglesias, G. Fischer and M. T. J. Livermore, Climate change and
world food security: a new assessment, in M. L. Parry and M. T. J. Livermore (eds.), A new
assessment of the global effects of climate change, Global Environ. Change, 1999, 9 (Supplemental
Issue), s52—s67.
IPCC, R. T. Watson, M. C. Zinyowera and R. H. Moss (eds.), Climate Change 1995: Impacts,
Adaptations and Mitigation of Climate Change: Scientific-Technical Analyses — Contribution of
Working Group II to the Second Assessment Report of the Intergovernmental Panel on Climate
Change, Cambridge University Press, Cambridge, 1995.
C. Rosenzweig and M. L. Parry, Potential impacts of climate change on world food supply. Nature,
1994, 367, 133—138.
International Benchmark Sites Network for Agrotechnology Transfer (IBSNAT), Decision Support
System for Agrotechnology Transfer Version 2.1 (DSSAT V2.1). Dept. Agron. & Soil Sci. College
Trop. Agric. And Hum. Resources. Univ. Hawaii, Honolulu, 1989.
M. Parry and M. Livermore
110