Geoscience Reference
In-Depth Information
systems would be available? Would electronic detection and monitoring
be so advanced that advanced hybrid road-air-water drones would be
patrolling the borders and ready to zap transgressors with some as-
yet-undiscovered device so frightening that even a coyote would hesi-
tate to cross?
Perhaps we could take a stab at answering these questions. But even
then our job would be only half done. Recall that people migrate primar-
ily to improve their economic fortunes. We would then need to mea-
sure the impact of global warming on the future incomes of countries
and infer the impact of these income changes on migration trends. To
be realistic, we could probably make an estimate of the impact of global
warming on today's world, incomes, borders, and technologies. But these
elements are likely to change dramatically over the coming century, so
we need to be very cautious in any assessment of the impacts of global
warming on migration more than a few years into the future.
Environmental migration exemplifi es the diffi culties of projecting
climatic impacts. Human societies and economies are extensively man-
aged systems. If climate change increases exposure to heat waves or
vulnerability to the rising seas, we would expect that societies would
take steps to reduce vulnerabilities through air conditioning and coastal
policies. Moreover, if most countries continue to improve technologies
and living standards, we would expect that most poor countries (who
today can barely afford such investments) will increasingly be able to
protect themselves against climatic extremes just as Miami and Rotter-
dam do today. While no law of economics ensures that historical trends
will continue, it seems likely that the poorer countries will follow the
path of richer countries and will protect their peoples and societies
from environmental stresses.
The lesson here is that we are likely to overestimate the economic
impacts if we simply impose estimated climate changes on current soci-
eties. In considering the impact of climate change in the late twenty-
fi rst century, two major trends can be seen—even through the fuzzy
telescope. The fi rst is that, under the scenarios that produce dangerous
climatic change, most countries will be much richer than they are
today. Clearly we should not assume that African countries will have
