Emissions Scenarios - IPCC

196 An Overview of Scenarios
Table 4-7: Growth rates (% per year) of income per capita (using GDP at 1990 prices and exchange rates) in the world and by
region. Historical data from 1950 to 1990 from Maddison (1989,1995), UN (1993a, 1993b), and Klein Goldewijk and Battjes
(1995). Numbers in brackets give minimum and maximum values of all SRES scenarios.
Growth Rates of Income Per Capita (%)
1990-2050 1990-2100
Region 1950-1990 Al A2 Bl B2 Al A2 Bl B2
OECD90 2.8 1.6 1.1 1.5 1.2 1.6 1.1 1.2 1.1
(1.2-1.8) (0.8- -1.6) (1.2-1.6) (1 .0-1.4) (1.2-1.7) (0. ,8-1.2) (1.2-1.3) (0.9-1.3)
REF 3.7 4.0 1.9 3.0 3.0 3.3 2.0 2.8 2.4
(2.8-4.5) (0.5- -2.2) (2.7-3.6) (1 .9-3.3) (2.5-3.4) (1. ,5-2.0) (2.6-2.8) (1.6-2.6)
IND 2.9 2.0 1.2 1.7 1.4 1.9 1.2 1.5 1.2
(1.3-2.1) (0.8- -1.8) (1.5-1.8) (1 .1-1.6) (1.3-2.0) (0, ,9-1.4) (1.4-1.5) (1.0-1.4)
ASIA 4.4 5.5 2.7 4.8 4.7 4.4 2.5 3.9 3.3
(5.1-5.9) (2.7- -3.6) (4.6-5.5) (3 .3-4.8) (3.9-4.7) (2, ,4-2.9) (3.8-4.2) (3.1-3.4)
ALM L6 4.0 1.9 3.5 2.4 3.3 1.9 3.0 2.1
(3.5-4.4) (1.7- -2.2) (3.1-3.9) (1 .7-2.7) (3.1-3.5) (1. ,8-2.1) (2.8-3.2) (1.9-2.5)
DEV 2.7 4.9 2.4 4.2 3.8 4.0 2.2 3.5 2.8
(4.4-5.2) (2.3- -3.0) (3.9-4.8) (2 .5-3.9) (3.6-4.1) (2. ,2-2.6) (3.4-3.7) (2.6-3.0)
WORLD 2.2 2.8 1.1 2.3 1.8 2.7 1.3 2.2 1.6
(2.2-2.9) (0.7- -1.5) (2.1-2.6) (1 .1-1.9) (2.2-2.8) (1. ,3-1.5) (2.2-2.4) (1.4-1.7)
dispute within the SRES writing team because they imply high
productivity growth (see Box 4-5 and, for a contrasting
viewpoint and scenario 1п1ефге1а11оп, Box 4-6). However, it is
agreed that such scenarios of high productivity growth and
smaller income-per-capita disparities cannot be ruled out, even
if they certainly are very challenging from the perspective of
recent growth experiences in a number of regions, most notably
Africa. There is also agreement that the assumptions deployed
for the SRES scenarios are within the range suggested by the
literature (see Chapter 2). In this the highest GDP growth is up
to US$700 trillion by 2100 compared to US$550 trillion in the
highest SRES scenario. For scenarios developed within the
context of sustainability analyses, reductions in per capita
income gaps also occur faster than for any of the scenarios
presented here.
Important differences remain between models in terms of 1990
base-year data on economic activity levels. Even after
differences in regional definitions are accounted for, 1990
regional GDP differences between models range up to ±32% in
a few cases. Such differences are particularly pronounced for
developing countries, where in many cases national currencies
are not freely convertible and thus important uncertainties on
the applicable conversion rates remain (World Bank, 1999).
Differences for OECD countries are much smaller (+3% across
the models) and because of their current dominance in global
economic activity (and counterbalancing effects), 1990 global
GDP numbers agree well across the models (±5%). Scenario
comparisons, especially at the regional level, ai'e therefore best
based on a comparison of growth rates (see Chapter 2), and the
SRES scenarios are no exception.
Historical data indicate that, even though the process of
economic growth is heterogeneous across countries and over
time, the patterns of growth show certain similarities.
Economic "catch-up" follows a general dynamic pattern,
characterized by initially accelerating economic growth rates
that pass through a maximum, and decline once the industrial
base of an economy becomes established. This overall feature
of growth dynamics is reflected in all the SRES scenarios,
albeit timing and magnitude vary across the four scenario
families. This variation reflects the scenario-specific storylines,
as well as particular relationships to other driving-force
variables, such as demographics, described in the scenario.
4.4.4.1. Al Scenarios
By design (see Section 4.3) the "High Growth" scenario family
Al explores a world in which future economic development
follows the pattems of the most successful historical examples
of economic development catch-up. Free trade, continued
innovation, and a stable political and social climate enable
developing regions to access knowledge, technology, and
capital. Combined with a rapid demographic transition, this is
assumed to lead to acceleration in time and space of economic
growth compared to the historical OECD experience since the
19* century. The global economy is projected to expand at an
average annual rate of 2.9% to 2100 (see Table 4-5), roughly in
line with historical experience over the past 100 years (of 2.7%
per year, see Chapter 3). Such growth rates are considered high
by the current scenario literature (see Chapter 2). Compared to
historical experience, however, the broad-based nature of
economic development catch-up (i.e., no region "is left
behind") is without precedent. The 2.9% per year economic