Figure 2-12: Global CO2
emissions from energy and industry, historical development from 1900 to 1990 and
in 40 SRES scenarios from 1990 to 2100, shown as an index (1990 = 1). The range
is large in the base year 1990, as indicated by an “error” bar, but
is excluded from the indexed future emissions paths. The dashed time-paths depict
individual SRES scenarios and the blue shaded area the range of scenarios from
the literature (as documented in the SRES database). The median (50th), 5th, and
95th percentiles of the frequency distribution are shown. The statistics associated
with the distribution of scenarios do not imply probability of occurrence (e.g.,
the frequency distribution of the scenarios in the literature may be influenced
by the use of IS92a as a reference for many subsequent studies). The 40 SRES scenarios
are classified into six groups. Jointly the scenarios span most of the range of
the scenarios in the literature. The emissions profiles are dynamic, ranging from
continuous increases to those that curve through a maximum and then decline. The
coloured vertical bars indicate the range of the four SRES scenario families in
2100. Also shown as vertical bars on the right are the ranges of emissions in
2100 of IS92 scenarios, and of scenarios from the literature that apparently include
additional climate initiatives (designated as “intervention” scenarios
emissions range), those that do not (“non-intervention”), and those
that cannot be assigned to either of these two categories (“non-classified”).
