Emissions Scenarios - IPCC

124 Scenario Driving Forces
Figure 3-12: Metals intensity of
use per unit of GDP as a function
of GDP per capita for 13 world
regions. Metals include refined
steel and MedAUoy (the sum of
copper, lead, zinc, tin, and nickel).
GDP here is measured in terms of
purchasing power parities (PPP).
The dashed curves are isolines that
represent a constant per capita
consumption of metals. The thick
pink line indicates the inverse U-
shaped curve that best describes the
trends in the different regions as
part of a global metal model. Data
source: Van Vuuren et al., 2000.
regions', again as a function of per capita income (Nakicenovic
et al., 1998a).
The most important conclusion to retain from Figures 3-12 and
3-13 is that energy and materials intensity (i.e. energy use per
unit of economic output) tend to decline with rising levels of
GDP per capita. Thus, energy and material productivity - the
inverse of energy intensity - improve in line with overall
macroeconomic productivity (as represented, e.g., by GDP per
capita levels). Also, they tend to deteriorate when productivity
levels fall, as happened during the start of the deep economic
recession in Central and Eastem Europe (Govemment of
Russian Federation, 1995). A corollary of this relationship is
that material and energy intensities decline the faster per capita
income grows. Thus, overall economic productivity growth
(GDP per capita growth) and reductions in materials and
energy use per unit GDP (materials and energy productivity
growth) are closely related. The fundamental reason is that
high macroeconomic growth presupposes accelerated rates of
technical change and corresponds with a fast turnover of
capital stock and, hence, a faster incorporation in the economy.
This represents an important new finding for long-term energy
and emissions scenarios that have, to date, largely treated
economic and resource productivity growth as independent of
' The regional definition used in Nakicenovic et al., 1998a, includes:
AFR: Sub-saharan Africa; CPA: China and Centrally Planned Asia;
EEU: Central and Eastem Europe; FSU: Newly Independent States
of the former Soviet Union; LAM: Latin America and the Caribbean;
MEA: Middle East and North Africa; PAO: Pacific OECD;
Other Pacific Asia; SAS: South Asia; WEU: Western Europe.
PAS:
each other. According to recent empirical and theoretical
findings, they no longer can.
Two final caveats are important. First, growth in productivity
and intensity improvement growth have historically been
outpaced by economic output growth. Hence, materials and
energy use has risen in absolute tenns (see Nriagu, 1996;
Watson et ai, 1996; Griibler, 1998a). The second caveat is that
energy and material intensity are affected by many factors
other than macroeconomic productivity growth and resultant
income. OECD (1998b) notes that high rates of productivity
increase have been associated in the past with new competitive
pressures, strong price or regulatory incentives, catching up or
recovery, and a good "climate for innovation." Also, the
emergence of new technologies and resource-strategic
considerations has led to rapid productivity growth.
Table 3-3 summarizes selected macroeconomic, labor, energy,
and material productivity increases that have been achieved in
a range of economies and sectors at different times. Principally,
it demonstrates that the least likely assumption for future
scenarios from historical evidence is absence of productivity
growth. Human ingenuity (as reflected in new technologies and
new practices) historically has responded to puiposeful action
(R&D and inventive activities) and to a wide range of policies
to improve vastly productivity in the use of all factors of
production. Of course, it remains uncertain how future
productivity growth rates will diffuse nationally, regionally,
and internationally. The essential lesson provided by history is
that change is continuous and pervasive. From that perspective,
static or "business-as-usual" scenarios need to be replaced by
"dynamics-as-usual" scenarios, which divide into "fast" and