Archives:
Previous Global Population Projections

• Conditional probabilistic population forecasts by 13 world regions (2000-2100)
  
• Human capital projections by 13 world regions (multi-state projections, 2000-2030)
  
• Population scenarios for the Millennium Ecosystem Assessment (2000-2100)
  
• Global population projections by 13 world regions (1990-2050)
  
• Population projections for the IPCC special report on emission scenarios (1990-2100)
• Brief Descriptions of Population Projections



• Conditional probabilistic population forecasts by 13 world regions (2000-2100), 2001
• Human capital projections by 13 world regions (multi-state projections, 2000-2030), 2003
• Population scenarios for the Millennium Ecosystem Assessment (2000-2100), 2003/2004
• Global population projections by 13 world regions (1990-2050), 1996
• Population projections for the IPCC special report on emission scenarios (1990-2100), 1996

CONDITIONAL PROBABILISTIC WORLD POPULATION PROJECTIONS BY 13 WORLD REGIONS, 2001

A key element of the probabilistic method is to make projections that are not just simple numbers, but distributions of possibilities at future dates. These distributions allow analysis that are impossible or inappropriate with non-probabilistic forecasts. For instance, types of applications are the probabilistic analysis of age structures, conditional probabilistic forecasting, and learning through the passage of time.

By thinking about population projections in ranges and not in single numbers, we can see how uncertain forecasts of measures such as the proportions of population at age 60 and above really are. Further, we can see that conditional forecasts are also uncertain and that their uncertainties change with the conditioning variables. And passive learning shows how a distribution of probabilistic paths can allow us not only to make forecasts, but also to predict the forecast that we would make at future times conditional on our observations between then and now. All these are vital for decision-making, and help to understand what the potential effects of decisions/policies could be.

More information and a selection of probabilistic population forecast results can be downloaded at POP's 2001 Probabilistic Projection website.

WORLD HUMAN CAPITAL PROJECTIONS, 2003/2004

Projections of future human capital are of highest interest for studies on future capacities for societies to adapt to environmental change and other global and local challenges. They apply the demographic methodology of multi-state population projections. The multi-state model divides the population by age and sex into 'states', in this case into four groups of educational attainment. The key parameters are four sets of age and sex-specific educational transition rates, that is the probability for young men and women to move from one state to another (e.g. from primary to secondary attainment). Another important feature that gives the model a dynamic element, is to consider different fertility rates for different educational groups. That means, even with constant status-specific fertility, a change in the relative size of the educational subpopulation results in changes in the fertility rate of the total population. For certain scenarios, intergenerational transmission of education is considered.

Population projections by level of education are a logical next step to improve population forecasts and to make them more relevant. More detailed information and the projection results are available at POP's Educational Projection website.

POPULATION SCENARIOS FOR THE MILLENNIUM ECOSYSTEM ASSESSMENT, 2003/2004

The Millennium Ecosystem Assessment (MA) is the most extensive study ever of the linkages between the world’s ecosystems and human well-being. The POP project developed the population projections being used in the MA's forthcoming report on future scenarios of socio-economic development and ecological outcomes. This work required developing a new methodology for deriving individual scenarios from POP's conditional probabilistic projections. This methodology breaks new ground by providing a quantitative estimate of the uncertainty associated with the individual projections used in the MA scenarios.
Click here to learn more about POP's population scenarios for the MA.

GLOBAL POPULATION PROJECTIONS BY 13 WORLD REGIONS, 1996

The 1996 world population projection uses expert-based assumptions for the future development of fertility, mortality, life expectancy and migration. For the projection, the globe was divided into 13 major world regions. By doing so, much of the world's heterogeneity is taken into account, and we need not bother with national particularities, especially with respect to migration. The crucial difference with respect to existing global population projections lies in the specification, justification, and combination of alternative scenario assumptions and in the definition of the first probabilistic world population projections. Detailed information on the assumptions, summaries of results, and a description of the methodology as well as data sets are provided by the IIASA Population Program at www.iiasa.ac.at/Research/POP/docs/Population_Projections_
Results.html.

POPULATION PROJECTIONS FOR THE IPCC SPECIAL REPORT ON EMISSION SCENARIOS, 1996
Long-term projections: 1990 - 2100

POP provided demographic expertise to an international writing team for the Special Report on Emission Scenarios of the IPCC, the Intergovernmental Panel on Climate Change. The task was basically to decide which population scenarios developed by IIASA would be more consistent with the range of long-term emission scenarios developed by the SRES team. IIASA's population scenarios were chosen as low/high brackets (SRES A1-B1 and A2) whereas the United Nations Population Division provided the central demographic scenario (Scenario B2).

IIASA's population projections are particularly adapted to the Emission Scenarios for the following reasons. They are long range up to the year 2100, the spatial dissaggregation in 13 regions matches those of most models used to develop the SRES; fertility, mortality, and migration are co-varied in a consistent way that leaves room for substantive consideration of justifiable alternative future trends in the components. Finally, a large number of scenario variants are available. The SRES was developed along four story lines representing the playing out of certain economic, social and environmental paradigms. Two population scenarios were adopted from the population projections realized at IIASA in 1996 and presented in The Future Population of the World: What Can We Assume Today? Revised and Updated Edition edited by Wolfgang Lutz and published by Earthscan (1996).

The IPCC Task Group for Climate Impact Analysis (TGCIA) has requested the IIASA Population Program to produce country-level population projections consistent with the IIASA regional projections used in SRES (for scenarios A1-B1 and for scenario A2) (2001). More information at the IPCC Data Distribution Centre website.

Responsible for this page: Suchitra Subramanian
Last updated: 19 Sep 2011