Environmental Engineering Reference
In-Depth Information
tives. Civilization's course is not preordained but remains
open to our choices.
Not everybody would agree with this conclusion.
We may be embarked on an irreversible course of de-
struction, the only uncertainty being about the eventual
causes of our demise: environmental degradation, nuclear
war, or a virulent pandemic. Gentler, but no less com-
forting, scenarios of human demise are possible. Wesley
(1974) put forth a reasoned case for an early elimination
of people by machines. He argued that the point of no
return came around 1830, when the steam engine be-
came more efficient than muscles. Since then humankind
has become critically dependent on machines, whose
evolution (including vigorous reproduction and selection
for higher fitness, increased speciation, improved ecolog-
ical efficiency, and rapidly growing mass) has destroyed a
great deal of the Earth's life. My calculations show that
by 2000 the global car fleet alone was 1 OM heavier
than the anthropomass (@1.5 Gt vs. @100 Mt) and that
its carbon needs were much higher and are rising much
faster (humans harvest @1.3 Gt C as food; almost 2.5
Gt C goes into car making and fuels).
Eventually machine mass could surpass total planetary
biomass. Machines could become autonomous, in which
case Wesley (1974) would allow no more than one more
century before the complete disappearance of Homo sapi-
ens. More recently Moravec (1999) and Kurzweil (1990)
suggested a much faster takeover by superintelligent
computers, claiming that perhaps as soon as 2040 think-
ing machines cut loose, develop hyperintelligence, and
bring about our demise. These may be incredibly pre-
scient visions or just self-destructive wishful thinking. In
any case, such multidecadal forecasts are always question-
able, and truly long-term perspectives (10
2
-10
4
years,
the latter equal to the time it took us to move from Neo-
lithic foraging to fossil-fueled civilization) remain utterly
elusive.
Hubbert (1962) popularized the notion of fossil-
fueled civilization as a brief interlude between the solar
past and the solar (nuclear?) future. Many believe that
rapid climate change may imperil civilization long before
any real shortages of relatively expensive fossil fuels, per-
haps even before 2100. Four or five generations is a short
span even in historic terms, but what could be accom-
plished during that brief period is best appreciated by try-
ing to look at the end of the twentieth century from the
vantage point of 1900. Crises and discontinuities provide
the challenge and drive adaptive change, and the inevit-
able transition from fossil-fueled societies to a new global
system will not be marked by applying ancient precepts
to unprecedented tasks.
Energy decisions involve often irreconcilable consider-
ations of thermodynamic efficiency, personal comfort,
resource depletion, economic well-being, environmental
degradation, national security, social stability, and demo-
cratic values. This reality is incompatible with any
strategic optima; it merely admits a choice of practical
alternatives. Optimal allocation of finite resources would
not be possible unless we knew the demand over the en-
tire future. Hotelling (1931) knew this, but thousands of
modelers apparently do not. And often there is an intu-
itive sense of an optimum where none exist. During pre-
industrial millennia, the horse provided the fastest
individual land transport, but there is no best way to sit
on a horse (Thomson 1987). True believers sell optimal
photovoltaic, fusion, or hydrogen futures, but the safest
bet is that there is no single best solution of the global
energy challenge.
All we can do with some semblance of rationality
is to map our tasks for the next few generations. The
