Geoscience Reference
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nario might unfold and then discuss its implications for global warming
policy.
Forecasting future technological developments is inherently diffi cult.
If I knew what future technologies would succeed, then, as with fore-
casting future stock market movements, I could be fabulously famous
and wealthy. But let's consider some technological science fi ction. Sci-
entists and technologists who speculate about future trends generally
anticipate that breakthroughs might come from some combination of
advanced computation, robotics, and new materials.
Inventor-futurist Ray Kurzweil has proposed a vision for a low-
carbon but energy-rich future. He suggests that molecular nanotech-
nology can reduce the fabrication costs of solar power to a tiny fraction of
the current level, enabling placement of inexpensive solar cells on build-
ings, vehicles, and even clothing. He also envisions using solar power in
space to beam vast quantities of energy to earth via microwaves, with
the materials lifted to space using a space elevator.
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As with other forecasts of revolutionary breakthroughs, it is hard
to know how seriously to take them. Is the likelihood of such a break-
through in the next half century 20 percent? Or 2 percent? Or 0.002
percent?
To begin with, we defi nitely should not rule out these kinds of
radical technological breakthroughs. A century ago, no one would have
dreamed of today's Internet, artifi cial intelligence, or DNA sequencing.
Moreover, if we look at Figure 39, we see that solar photovoltaic costs
have declined sharply in the past fi ve decades.
But a little refl ection suggests that potential radical technological
breakthroughs will not solve the global warming dilemma. The reason
is that we need insurance against bad outcomes, not to cover good out-
comes. Fire insurance is a useful analogy. We buy fi re insurance in case
our house burns down, not for the surviving house, or for a house
whose value rises sharply. Our premiums insure against the worst-case
scenario, not the best-case scenario.
Here is a fable that will make the point. Suppose someone invents
an ingenious bug that eats carbon in the atmosphere and then fl ies into
