Geoscience Reference
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a wide range of estimates on this number. A further spin might fi nd
that farmers can adapt well and global food production is unaffected,
while a ball in a red pocket might lead to particularly adverse climate
impacts in the current grain belts of the world and therefore much
greater damages than we had anticipated.
But in the Climate Casino, the ball also might land on zero or dou-
ble zero. If it lands on zero, we fi nd signifi cant loss of species, ecosys-
tems, and cultural landmarks like Venice. If it lands on double zero, we
see those impacts and even more serious ones. We might begin to see a
rapid collapse of the West Antarctic Ice Sheet, or melting of vast por-
tions of permafrost, or changes in the ocean currents that currently
warm the North Atlantic community, or mass extinction in the oceans
because of the cascading impacts of ocean acidifi cation.
We might also worry that the climatic roulette wheel has a weird
construction. We might not even know what the numbers are, and per-
haps there are many more red pockets than we thought because we
underestimated the number of tipping points. Also, the numbers might
change depending upon the outcome of the earlier wheel spins. We
also fi nd that when there are multiple unfavorable spins, the outcomes
are even more costly because of nonlinearities in the physical system.
Three reds in a row plus a double zero might lead to even more unfa-
vorable outcomes as rapid growth in emissions adds up to a larger-than-
expected climate impact plus a shift in monsoonal patterns that has a
yet further impact on the Indian subcontinent. In the Climate Casino,
the total climate impacts are more than the sum of the individual
parts.
A sensible strategy would suggest an insurance premium to avoid the
roulette wheel in the Climate Casino. We should add a premium in our
damage estimates to refl ect the casino risks on top of the identifi ed dam-
ages shown in Figure 22. We need to incorporate a risk premium not
only to cover the known uncertainties such as those involving climate
sensitivity and health risks but also the zero and double zero uncertain-
ties such as tipping points, including ones that are not yet discovered.
How large a risk premium should we add? This is the subject of in-
tensive research and discussion among specialists today, and experts
