Geoscience Reference
In-Depth Information
5
TIPPING POINTS IN THE
CLIMATE CASINO
People might wonder how concerned they should be about the tem-
perature trends described thus far. A change of 2 or 3°C does not seem
that alarming. After all, we often experience that much change in one
hour in the morning. Moreover, the temperature changes envisioned are
small relative to those that individuals and groups experience through
migration. People today happily move from Snowbelt to Sunbelt to en-
joy the warmer lifestyle. If you move from Minneapolis to Phoenix, you
will be moving to a climate that is 13°C warmer.
But this description ignores the real risks. The problem is not a
simple rise in average temperature but rather the accompanying physi-
cal, biological, and economic impacts of such a change—in particular,
the thresholds and nonlinear responses that may be encountered. A
rise in our body temperature from 98°F to 104 or 105°F does not sound
like a large change, but it may signal a deadly infection.
The importance of thresholds is easily illustrated by the following
example. Consider what happens when you are driving along on a wet
road. The surface temperature changes from 1 degree above freezing to
1 degree below freezing. In an instant you go from slippery to poten-
tially deadly conditions.
A less dramatic example is what happens every year to my out-
door basil plants. They happily produce leaves to have with pasta until
one night in the late fall when the temperature drops below freezing.
When I go out to gather some leaves, they have turned black and are
ruined.
