IMAGE framework summary/Description: Difference between revisions
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Key inputs for the model are projections describing direct and indirect drivers of global environmental change ([[Scenario drivers]]). Most of these drivers (such as technology and lifestyle assumptions) are used as input in various subcomponents of IMAGE (see figure on the right). Clearly, the exogenous assumptions made on these factors need to be consistent. To ensure this, so-called storylines are used, brief stories about how the future may unfold, that can be used to derive internally consistent assumptions for main driving forces. Important categories of scenario drivers include demographic factors, economic development, lifestyle, and technology change. Among these, population and economic development form a special category as they can be dealt with in quantitative sense as exogenous model drivers. Other drivers mostly concern assumptions in different subcomponents of IMAGE, for examplee.g. both the yield assumptions in the crop growth model and the performance of solar power production in the energy model depend on a more generic description of the rate of technology change. | Key inputs for the model are projections describing direct and indirect drivers of global environmental change ([[Scenario drivers]]). Most of these drivers (such as technology and lifestyle assumptions) are used as input in various subcomponents of IMAGE (see figure on the right). Clearly, the exogenous assumptions made on these factors need to be consistent. To ensure this, so-called storylines are used, brief stories about how the future may unfold, that can be used to derive internally consistent assumptions for main driving forces. Important categories of scenario drivers include demographic factors, economic development, lifestyle, and technology change. Among these, population and economic development form a special category as they can be dealt with in quantitative sense as exogenous model drivers. Other drivers mostly concern assumptions in different subcomponents of IMAGE, for examplee.g. both the yield assumptions in the crop growth model and the performance of solar power production in the energy model depend on a more generic description of the rate of technology change. | ||
For population, the IMAGE model mostly uses exogenous assumptions (total population per region, household size and urbanization rate). Also the population projections of the [[PBL]] [[GISMO model]] can be used, which allows, in principle, to also account for feedback of environmental factors (e.g. air pollution and undernourishment) on population growth (see [[Impacts]]). For that purpose, population can be downscaled to the grid level. For economic variables such as [[GDP]], usually also exogenous assumptions are used. In most studies the economic projections are developed by macro-economic models based on the same storylines as the rest of the IMAGE model to ensure consistency. Sector specific economics and household consumption can be derived directly by such models, in addition the latter can be broken down into income categories, reflecting the so-called [[GINI]] | For population, the IMAGE model mostly uses exogenous assumptions (total population per region, household size and urbanization rate). Also the population projections of the [[PBL]] [[GISMO model]] can be used, which allows, in principle, to also account for feedback of environmental factors (e.g. air pollution and undernourishment) on population growth (see [[Impacts]]). For that purpose, population can be downscaled to the grid level. For economic variables such as [[GDP]], usually also exogenous assumptions are used. In most studies the economic projections are developed by macro-economic models based on the same storylines as the rest of the IMAGE model to ensure consistency. Sector specific economics and household consumption can be derived directly by such models, in addition the latter can be broken down into income categories, reflecting the so-called [[GINI coefficient]] (a measure of the disparity in income distribution). | ||
Assumptions for future scenarios start from observed trends in recent decades and this is also the base for the baseline scenario used in the Rio+20 study ([[PBL, 2012]])). The global population is based on the UN medium projection and grows to about 9 billion people in 2050, the increase mostly occurring in developing countries. The economic projection shows that developing countries increasingly dominate the world economy in terms of total GDP. For the [[OECD]] countries, the baseline scenario assumes a long-term economic growth rate of 1-2% per year over the whole scenario period. In the short term, per capita growth rates in Asia and Latin America are much higher, but they start to converge gradually to a long-term growth rates of around 2% per year. Africa, in contrast, shows a later peak in economic growth. | Assumptions for future scenarios start from observed trends in recent decades and this is also the base for the baseline scenario used in the Rio+20 study ([[PBL, 2012]])). The global population is based on the UN medium projection and grows to about 9 billion people in 2050, the increase mostly occurring in developing countries. The economic projection shows that developing countries increasingly dominate the world economy in terms of total GDP. For the [[OECD]] countries, the baseline scenario assumes a long-term economic growth rate of 1-2% per year over the whole scenario period. In the short term, per capita growth rates in Asia and Latin America are much higher, but they start to converge gradually to a long-term growth rates of around 2% per year. Africa, in contrast, shows a later peak in economic growth. | ||
Revision as of 17:46, 17 December 2013
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