Second, even if we ignore the challenge of global population growth, it is
likely that per capita GDP will continue to rise over time. It is probably
inherent to human nature that individuals—in rich and poor countries
alike—strive to do better and improve their quality of life. And this desire
to increase per capita income will inevitably lead to increases in world
GDP.
As a result, world GDP can be expected to rise over time, not fall. For the
world as a whole, the average GDP growth rate is usually between 4 and
5 percent per year. It follows that with unchanged “intensities” in
Equation 17-1 , the typical growth in world GDP will lead to growth in
GHG emissions of between 4 and 5 percent per year.
Reducing the Energy Intensity of GDP
Now consider the second component in Equation 17-1 , the energy
intensity of GDP—the amount of energy that is used to produce one
dollar’s worth of real GDP. Taken by itself, a reduction in the energy
intensity of GDP will reduce the annual emissions of greenhouse gases.
Improvements in technology, driven in part by firms’ efforts to economize
on inputs that are becoming increasingly scarce and expensive, are one
driver for reductions in the energy intensity of GDP. Another is that as
the structure of the economy continues its gradual adjustment away from
energy-intensive manufacturing and toward the less-energy-intensive
service sector, less energy is used even if the same level of aggregate
output is produced. In countries like Canada and the United States, the