ABSTRACT
Changes in products, devices, processes, and practices—that is, changes in technology—largely determine the development and consequences of industrial society. Historical evidence (e.g., Freeman 1989; Mokyr 1990; Maddison 1991; Grübler 1998) and economic theory (Tinbergen 1942; Solow 1957; Denison 1962, 1985; Griliches 1996) confirm that advances in technological knowledge are the single most important contributing factor to long-term productivity and economic growth. Technology is also central to the long-term evolution of the environment and to development problems now on policy agendas worldwide under the general rubric, “global change.” Although technology is central, technological change is typically the least satisfactory aspect of global change modeling. Each of the factors that determine the wide range of projected emissions of, say, carbon dioxide (CO2)—such as the future level of economic activity (largely driven by advances in productivity), the energy required for each unit of economic output, and the carbon emitted for each unit of energy consumed—is a function of technology. This also applies to the technological linkages in any kind of macro or sectoral production function (Abramovitz 1993). Consequently, technology largely accounts for the wide range seen in published long-term carbon emission estimates. A recent review of the literature (Nakicenovic et al. 1998b) indicates an emissions range spanning from 2 GtC (gigatons, 1015 grams, of elemental carbon) to well above 40 GtC by 2100. This wide span is largely explained by differences in technology-related assumptions such as macroeconomic productivity growth, energy intensities, and availability and costs of low- and zero-carbon technological alternatives.
