Population Data Download - First Modeling Round

all data downscaled to country level population data are provided as Excel tables

Preliminary Population Scenario for the MA Storyline “Elites”/“Global Bridges, Local Barriers”

February 5, 2003

Prepared by Brian O’Neill (IIASA), Sergei Scherbov (Austrian Academy of Science; IIASA), and Anne Goujon (Austrian Academy of Science; IIASA)

This population scenario was developed for use by the Millennium Assessment Scenarios Working Group, for use in the quantification of storylines. It is based on the IIASA 2001 probabilistic projections for the world (see Lutz et al., 2001, Nature), taking into account judgments by the MA Scenarios Modeling Group (as expressed at the Amsterdam meeting in January 2003) regarding the constraints placed on the scenario by the MA storyline. Based on these judgments, the following criteria were adopted in devising the scenario:

• Population size at the global level should be at roughly the 90th percentile of the unconditional distribution of population size in the IIASA 2001 projections;
• Population size in each of the 5 MA world regions should also be relatively high, at approximately the 90th percentile if possible;

Further interpretations of the storyline made at IIASA, based on the draft storylines circulated in late January, led to the judgment that this relatively high population growth scenario should be achieved through a combination of relatively high fertility, relatively low life expectancy, and relatively low migration.

To operationalize these criteria, the method employed at IIASA in deriving the scenario consisted of:

1. Defining a set of conditional probabilistic projections for the world which met the above criteria, by drawing on the set of 2000 simulations that underlie the IIASA 2001 unconditional population projections. The criteria were implemented as follows:


1. Global population size, averaged over the period 2050-2100, should fall between the 85th and 95th percentiles of the unconditional distribution; Population size in each of the 5 MA regions, averaged over the period 2050-2100, should fall above the 67th percentile;
2. Fertility in each of the 5 MA regions, averaged over the period 2000-2050, should fall above the 33rd percentile;
3. Life expectancy in each of the 5 MA regions, averaged over the period 2000-2100, should fall below the 67th percentile;
4. Net migration in each of the 5 MA regions, averaged over the period 2000-2100, should fall below the 67th percentile.


2. Deriving a single deterministic scenario for fertility, mortality, and migration in each of the 13 regions used in the IIASA projection model, based on the medians of the conditional distributions for these variables;
3. Projecting future population size and structure based on this single deterministic scenario for fertility, mortality and migration at the level of 13 world regions; Downscaling the population size results to the country level using the same methodology applied to the population assumptions in the IPCC SRES scenarios, as documented on the IPCC TGCIA website (http://sres.ciesin.columbia.edu/tgcia).
4. Results are presented as total population in 5 years time steps between 2000 and 2100 for all countries, and aggregated into 11 UN regions, 5 MA regions, and the world. The format of the presentation of results is identical to the format of the results already available for the population assumptions used in the IPCC Special Report on Emissions Scenarios, as presented on the IPCC TGCIA website.

Projection results are provided in the form of an Excel table containing total population size in 5-year time steps over the period 2000-2100 for all countries, and aggregated into 11 UN regions, 5 MA regions, and the world. This format is identical to the one used to present the population assumptions used in the IPCC Special Report on Emissions Scenarios, available on the IPCC TGCIA website1. Further documentation of the methodology, input assumptions, and projection results is in preparation. Questions should be directed to Brian O’Neill (oneill@iiasa.ac.at).

As noted in the results file, there are a few minor exceptions: (1) the unit is persons (MA) instead of thousand persons (SRES); (2) Macao is in China and centrally planned Asia (MA) instead of being in Pacific Asia; (3) Three countries are added: Channel Islands in Western Europe, and French Guiana and Saint Lucia in Latin America; (4) There are 5 world regions (MA) instead of 4 (SRES).