This article demonstrates that large decreases in energy requirements
per unit economic output were achieved throughout the world and that c
arbon emissions have also decreased per unit energy. Energy is one of
the most important factor inputs so that decreases in specific energy
requirements contribute toward decreasing material intensity. Carbon d
ioxide emissions represent one of the largest single mass flows associ
ated with human activities. Therefore, decarbonization contributes in
a large way toward dematerializaton. At the global level decarbonizati
on occurs at about 0.3% per year, and reduction of energy intensity of
value added stands at 1% per year, resulting in overall carbon intens
ity of value added reduction of about 1.3% per year. The pervasiveness
of decarbonization in the world, is illustrated for five representati
ve countries. The case histories show that developing countries are un
dergoing basically the same process of decarbonization of final energy
use as do most developed ones. However, carbon intensity of primary e
nergy is increasing in some developing countries and should a reversal
not occur in the forthcoming decades, it is likely the decarbonizatio
n in the industrialized countries could be offset by this tendency. Th
us, the possibility cannot be entirely excluded that carbon dioxide em
issions would increase faster than economic growth. These opposing ten
dencies could be bridged in the future if the energy system restructur
es toward larger reliance on natural gas, biomass, nuclear energy, and
other zero-carbon options. For example, the methane economy could lea
d to a greater role for energy gases (and later hydrogen) in conjuncti
on with electricity. Such an energy system would represent a gigantic
step toward decarbonization and it would also be consistent with the e
mergence of new technologies that hold the promise of higher flexibili
ty, productivity, and environmental compatibility.