Geoscience Reference
In-Depth Information
areas more than 10 meters above sea level are relatively invulnerable to
SLR for the next century or two.
The global total might be of less concern if people, output, and eco-
systems could migrate freely around the world. In that unrealistic case,
people threatened by fl oods in Bangladesh would simply move to India
or Thailand or some other high ground, and continue their lives in a new
spot. Or take the case of Pudong, which is part of Shanghai, China. It lies
in a river delta, and geologists might worry whether this is a good place
for the tallest building in China. Yet the population of Pudong has grown
from 300,000 in 1950 to over 5 million today. Will they simply let the
building sink, or build a seawall, or move away when the oceans rise?
I emphasized above the diffi culties of projecting migration patterns
over long time horizons. Over short time horizons of less than a decade,
there is relatively little international migration for most countries. We
can take the extreme case—which is probably unrealistic over the time
frame of SLR—where people cannot move outside their country, or
where the cost of moving is large. For this question, we can examine
the distribution of human settlements in the red zone by country. Table
2005 population of each country living at or below 10 meters of eleva-
tion. The top part of Table 4 shows the ten countries that are most at
risk from SLR. More than half of the population and output of these
countries is in the 10-meter red zone. Most of these at-risk countries
are relatively small, but two are populous: the Netherlands and Ban-
gladesh.
The bottom part of Table 4 lists the eleven most populous countries
and shows the fraction of their populations, output, and area at risk.
Aside from Bangladesh, less than 10 percent of the populations and
output of the large countries are at risk. However, between 5 and 10
percent of the populations of the three most populous countries live in
the red zone.
Table 4 also illustrates the large differences in climate-change im-
pacts among different regions. Some countries will be greatly affected
by SLR (Bangladesh, the Netherlands, and the Bahamas), while others
will be completely untouched (land-locked Austria, Kazakhstan, and Bo-
