Emissions Scenarios - IPCC

Emission Scénarios 271
^ — BIT MESSAGE
— -Ti — BIHIGH
MESSAGE
B2 MESSAGE
• ~B2 AIM
4- - - B2ASF
1990 2000 20Ш 2020 2030 2040 2050 2060 2070 2080 2090 2100
•- - - B2 IMAGE
Figure 5-9: Standardized global NO^, emissions in SRES scenarios, classified into four scenario families (each denoted by a
different color code - A I, red; A2, brown; В1, green; B2, blue). Marker scenarios are shown with thick lines without ticks,
globally hai-monized scenarios with thin lines, and non-harmonized scenarios with thin, dotted lines (see Table 4-3). Black
lines show percentiles, means, and medians for SRES scenarios. For numbers on the two additional illustrative scenarios AlFI
and AIT see Appendix VII.
NMVOCs category are very different, so are their roles in
ozone formation and the (potential) health hazards associated
with NMVOCs. In this report NMVOCs are reported as one
group. In 1990, the estimated NMVOC emissions range
between 83 and 178 Mt, which after standardization (see Box
5-1) translates into 140 Mt (Figure 5-10). As discussed above
for NOjj emissions, not all models include this emissions
category or all of its sources; the most detailed treatment of
NMVOC emissions is given in the ASF model.
A relatively robust trend across all 40 scenarios (see Figure 5-
10) is a gradual increase in NMVOC emissions up to about
2050, as indicated by the 25* and 75"' percentile corridor, with
the range between 190 and 260 Mt by that year. Beyond 2050,
uncertainties increase with respect to both emission levels and
hends. As for N0^ emissions discussed above, the upper
bounds of NMVOC emissions are formed by fossil fuel
intensive scenarios within the Al scenario family (e.g. AlB-
'^SF), and the lower bounds by the scenarios within the ВI
family (with an impoitant altemative higher scenario Bl-ASF).
Characteristic ranges are between 60 and 90 Mt by 2100 in the
•ow emissions cluster and between 370 and 550 Mt in the high
emissions cluster. All other scenario families and individual
scenarios fall between these two emissions clusters, with the B2
marker scenario (B2-MESSAGE) closely tracking the median
of global NMVOC emissions from all the SRES scenarios.
In the Bl family marker (BI-IMAGE) emissions gradually
decline to 60% of the 1990 level by 2100 (Figure 5-10). The
Bl-AIM and Bl-MESSAGE trajectories are similai', but differ
somewhat from the В1 marker. They increase until the 2020s
(AIM) or even the 2050s (MESSAGE) at modest rates, but
subsequently decline to around or even below the В1 marker in
2100. The Bl-ASF profile, however, is radically different,
growing faster and continuously throughout the 2P' century.
By 2100, the NMVOC emissions in Bl-ASF increase to 350
Mt, or 2.5 times the 1990 level. This indicates the adoption in
this scenario of fairly different assumptions with respect to
technological development and emission controls as compared
to the rest of В1 scenarios. In the A2 family marker (A2-ASF)
and B2 family marker (B2-MESSAGE), emissions grow
steadily until 2050, by which time they are around 50% higher
than today. Thereafter, emissions in B2-MESSAGE decline
gradually, while in the A2 marker the growth continues to reach