Population and environment

TARGETS: a Global Change model

This theme addresses the interaction of population and environment. It is a theme that was initiated in the early 1990s at the invitation of and with funds from the National Institute of Health and the Environment (RIVM) in Bilthoven. The PRC was invited to assist in the design of a population and health module for TARGETS (Tool to Assess Regional and Global Environmental and Health Targets for Sustainability), a Global Change model. TARGETS includes separate submodels for energy, water, land and food. The model was published in the academic literature and was used to prepare the global environmental outlook published by the United Nations Environment Programme in Nairobi. Continued research resulted in two dissertations: research funded by RIVM (Hilderink, 2000) and research partly funded by RIVM (Ezra, 1997). Few micro-level research projects on population and environment exist, although actions at the individual and community level underlie the observed dependencies at the population levels. Funded by the United Nations Population Fund, a PhD study  (Ezra, 1997) was conducted in Northern Ethiopia to determine how people, mostly farmers, perceive climate change (drought) and environmental degradation, and how they adjust their life strategies and demographic behaviour - family formation and migration - in particular. Recently, a new project was initiated by IIASA with the participation of Scherbov. It involves the modelling of the population-environment-food security interaction in Africa (PEDA model). 

Results

Research on the population and environment theme produced two types of results. 

• First, a simulation model to assess the impact of developmental and policy factors on population dynamics was developed by Hilderink (RIVM). The model is based in part on earlier PRC work (see e.g. Van Vianen et al., 1995; Hutter et al., 1996) and  on case studies in India, China and Mexico. The model, called PHOENIX, is part of an integrated model of global change developed by RIVM. In addition, a visualization package is developed to display the various components of population dynamics graphically. The model was used to assess the effect of behavioural factors - such as contraceptive use, age at marriage and divorce - human development (HDI) and population policies on population growth in various regions of the world. Although the model was developed primarily for the study of the population-environment linkages, it can be used to monitor and forecast demographic change. 
• The second result is an outcome of a survey in North Ethiopia. Ezra (1997) found that persons in drought-prone areas are very aware of the environmental degradation over time. The stress accompanying food insecurity compelled people to realize the disadvantages of having large families (TFR about 8) and led to fertility decline without development taking place. This is additional proof that development is not a prerequisite for the onset of the fertility transition .