The human ecology of climate change - Climate Change: Biological and Human Aspects - page 371

Purely in greenhouse terms (which is not satisfactory for a broad range of other
economic purposes), using the emissions of carbon per person, as shown in Figure 7.1,
is one way to begin to address the difference in the monetary value of goods globally
(note, it is important to check whether it is carbon by weight or carbon dioxide being
used, as the latter is 3.666 times heavier than the former and yet refers to the same
amount of fossil fuel energy consumed). However, because there is no one perfect
measure of affluence, its inclusion in the Ehrlich-Holdren equation must be notional,
and therefore so must the equation itself. Even so, notions and theories do have merit
and can help illuminate issues - in this case that of environmental impact - and so
help frame solutions.
The final component of the Ehrlich-Holdren equation is T , the technological factor.
This too is difficult to quantify. Ehrlich and Holdren meant it to reflect the way dif-
ferent technologies impart different environmental impacts. For example, generating
a kilowatt hour of electricity from coal will impart a greenhouse impact as well as
involve part of the environmental impact of the coal mine. Whereas generating the
same electricity from a hydroelectric scheme will have a smaller greenhouse impact
(there will be a greenhouse impact from creating the cement and the energy used in
the dam's construction), there will also be the environmental impact of the volume of
dammed water on land use and so forth. So the different technologies have different
impacts and so T remains hard to quantify. More recently T has been replaced by some
users with a term reflecting the inverse of environmental efficiency of that population.
Energy that is produced with high environmental efficiency will have a low inverse
value and so contribute to a low environmental impact.
All the above demonstrates that quantifying environmental impact and hence the
cost of global warming is difficult, if not impossible, to assess with any accuracy.
Indeed, there is an entire sub-discipline of environmental economics that attempts
to come to grips with such problems. As we shall see, this problem affects one
type of greenhouse policy whereby permits to release carbon dioxide can be sold by
those who have invested in low-fossil fuel technology to those whose investments
are already tied up in high-fossil fuel technology. Because the estimation of impacts,
identifying of externalities and allocation of costs and benefits to energy technologies
is so fraught with difficulty, any system of greenhouse permit trading is likely to be
very complex and fail to reflect properly the impacts. Such systems also can easily
lead to gamesmanship whereby energy firms, and countries, play the system, so
undermining their contribution to greenhouse solutions (we shall return to this).
These difficulties aside, the consequences are that the impact of two populations
of similar size and affluence can be quite different. Similar ecosystems can support
different numbers of people depending on what they do. This notion did not begin
with, but was developed by, the American demographer Joel Cohen (1995). Spe-
cifically, Cohen suggests that it is the choices a society (or a population) makes that
affect the carrying capacity of that nation's environment. Consider two self-sufficient
populations of the same size. The birth of an extra person (in the absence of any
deaths) in each will increase those populations by one. Yet that extra person in one
population might go on to invent greenhouse-efficient systems or something else
that lowers environmental impact without reducing the goods and services generated
by that population. In the other population that person might become, to take an