Emissions Scenarios - IPCC

250 Emission Scénarios
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Bl MESSAGE
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BIHIGH
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Figure 5-3c: Global COj emissions from fossil fuels and industry in the Bl scenario family (standardized). The marker
scenario is shown with a thick line without ticks, the globally harmonized scenarios with thin lines, and the non-harmonized
scenarios with thin, dotted lines (see Table 4-3).
described in Box 4-6, A2-A1-MiniCAM has a lower
population than other scenarios of the A2 family, and a slower
rate of economic growth in the first half of the 2V^ century.
These in turn limit the growth in final energy demand until
after the onset of rapid economic growth around 2050.
Emissions also rise rapidly during the post-2050 period, as the
large growth in energy consumpfion results mostly from coal,
oil, and gas.
Two out of the six A2-family scenarios, A2-ASF and A2-AIM,
fall into the "high" cumulative CO2 emissions category. Three
scenarios, A2-MESSAGE, A2-IMAGE, and A2-MiniCAM,
belong to the "medium-high" category, and only the A2-A1-
MiniCAM scenario with its drastically different assumptions
about key driving forces falls in the "medium-low" category.
5.3.1.3. В1 Scenario Family
The strong trend toward ecologically more compatible
consumption and production patterns in the Bl family is
reflected by structural changes toward less energy- and
material-intensive activities, which lead to a partial decoupling
of welfare and energy demands. In the Bl marker
scenario (Bl-IMAGE; de Vries et al., 2000) the rapid
technological change toward resource saving and ecologically
sound solutions is assumed to spread very quickly, facilitated
by high capital stock turnover rates in currentiy less developed
regions. As a result, energy requirements in Bl-IMAGE
increase slowly and a shift away from fossil fuels eventually
breaks the already slow upward trend in carbon emissions
(Figure 5-3c). Emissions peak around 2040 at 12 GtC, twice
the 1990 level, and by 2100 the emissions fall below the baseyear
level to 5 GtC. Total cumulative carbon emissions in the
Bl-IMAGE scenario amount to 983 GtC by 2100. As for Al,
the population projection adopted for this scenario family
declines after 2050.
Rates of energy-intensity improvement in the first half of the
2P' century range quite widely in ВI family scenarios, and
lead to emission levels from 8.5 (BIT-MESSAGE) to 17.5 (Bl-
ASF) GtC in 2050. By 2100 the gap in annual emissions
naiTOws again, with final emissions between 3 and 8 GtC in all
the Bl scenarios (except В1-High-MiniCAM).
The Bl family also includes one scenario in which energyrelated
emissions continue to increase throughout the modeling
period, В1-High-MiniCAM. In this scenario the final energy
demand is assumed to rise more rapidly witli increasing
income than in the rest of the Bl scenarios. (The total carbon
emissions in BlHigh-MiniCAM decline slightly later in the
modeling period because of reduced land under management
and associated carbon sequestration.)
Total cumulative carbon emissions in the Bl scenario group
ranges between 770 and 1390 GtC by 2100. All but two Bl
scenarios fall in the low cumulative emissions category (Table
5-2).
5.3.1.4. B2 Scenario Family
In the B2 world, dynamics of technological change continue
along historical trends ("dynamics as usual"). The exploitation
of comparative regional advantages in energy resources and
technologies leads to regionally different mixes of clean fossil
and non-fossil supply. With the continued growth of population
and of income per capita, a steady increase of CO^ emissions