Emissions Scenarios - IPCC

152 Scenario Driving Forces
reduce SO2 emissions from coal use. Some refineries have
already advertised their investments (and efforts) to meet this
standard. In a landmark case on the Taj trapezium (a 10,400
km- area surrounding the Taj Mahal), the Supreme Court of
India has ordered a limit on the sulfur content of diesel sold in
this area to within 0.25% (Shukla, personal communication).
The Indian govemment has spent US$1.34 billion to reduce the
sulfur content in diesel from 1% to 0.25% by weight (Mr. K.P.
Shahi, Advisor to the Ministry of Petroleum and Natural Gas,
as quoted in Down to Earth, February 15, 1999, page 15).
These policies already have had an effect on emissions. Streets
et al. (2000) analyzed the impact since 1990 of these policies
and new energy and emissions factor data on emissions in
Asia.^ They found that emissions may have increased in Asia
from 16.9 MtS in 1990 to only 19.3 MtS in 1995, rather than
to the 26.7 MtS projected in the earlier studies with the
RAINS-ASIA model. The authors conclude that SOj emissions
in Asia have not grown nearly as fast as was thought likely in
the early 1990s, with major implications for projections
beyond the year 2000. It is probable that the emissions
trajectory will be even lower as a result of increasing
environmental awareness in many countries of Southeast Asia
and East Asia, the implementation of China's "two-controlzone"
policy, and the downtum of Southeast Asia economies in
the late 1990s (Streets et al, 2000).
In Latin America, the contribution of coal-fired power plants to
total power generation is relatively low and consequently SO2
emissions are lower than those in other regions. This
contribution is not expected to increase significantly in the
^ East Asia including China, Southeast Asia, and the Indian
subcontinent
future. It is expected that the rate of increase of SOj emissions
in Latin America will be reduced because environmental
agencies in several Latin American countries are already
enforcing strict SOj emissions standards. Also, increases in
power generation are expected to be mainly from combined
cycle natural gas plants (La Rovere and Americano, 1998).
Different methodologies have been developed to assess the
sulfur control scenarios in integrated assessment models.
Griibler (1998c) has summarized the literature, and classifies
three main modeling approaches:
• Ecological targets, and analysis of events when critical
acidification loads are exceeded (e.g., Amann et al.,
1995; Foell et al, 1995; Hettelingh et al, 1995; Posch
et al, 1996; Nakicenovic et al, 1997).
• The pollutant burden approach (e.g., Alcamo et al,
mi).
• Income driven approaches (e.g.. Smith et al, 2000).
Although models differ in their analytical representation of the
driving forces of sulfur reduction policies and also provide a
range of possible futures, invariably all scenarios yield
comparatively low future SOj emissions. Alcamo et al. (1997)
estimates a 95% probability that global SOj emissions will be
below 120 MtS by 2050 and decline thereafter. Their 50%
probability level suggests emissions of 90 MtS by 2050 and 57
MtS by 2100, the latter being identical to the median from the
scenario literature analyzed in Chapter 2.
Increasingly, energy sector and integrated assessment models
are able to link regional acidification models with simplified
climate models, which enables joint analysis of sulfur and
climate policies and impacts. Examples include the IMAGE
model (Posch et al, 1996) and the IIASA model (Rogner and
Figure 3-18: Range of future sulfur dioxide emission scenarios, in MtS. Note in particular the much lower emission range of
post-1995 sulfur dioxide emissions control and intervention scenarios compared with the earlier high-growth IS92a, b, e, and f
scenarios. Source: Griibler, 1998c.