find refuge), we need to also consider the possibility that the heat index is probably also higher in these places,
and air pollution worse. Multilevel studies that consider multiple aspects of the local environment, even multiple
dimensions of the social environment, are quite rare (Entwisle 2007). We need to think of local contexts as
“places,” socially interconnected and spatially situated. We also need to consider processes embedded in contexts
at multiple levels.
Climate change as reflected in changes in the environmental conditions present in specific places will
undoubtedly have many outcomes. I would like to draw attention to migration. Migration is both a response to
environmental change and also, by determining patterns of settlement, a factor affecting exposure to place-specific
risks of climate change. Environmental factors may act as “push factors,” contributing to a decision to move
out of a particular area. They may also serve as “pull factors,” shaping the desirability of particular locales as
potential destinations.
If people move as a consequence of climate change, the impact will be felt locally, but elsewhere as well.
For instance, international migration into the U.S. may be stimulated directly and indirectly by climate variability
and change elsewhere. Environmental refugees illustrate a direct impact, but indirect impacts are likely to be even
more important. Given the size and persistence of migration streams from Mexico and other parts of Central and
South America, for instance, it is important to consider the possibility that climate variability and change in these
regions may further increase immigration pressures. A global perspective on climate variability and change is
necessary even if ultimately, the concern is with impacts within the borders of the U.S. This is true not only with
respect to issues of human settlement, but also with respect to health and welfare. Climate variability and change
are global phenomena and impacts outside of the U.S. may have direct consequences for social systems within the
U.S.
Migration is a micro behavior with potential consequences at a macro level. When people move from
place to place, they change the local context in which they are themselves embedded as a kind of a swap. These
moves have consequences for neighborhoods as well, both the origin as well as the destination. Schelling
(1972), Bruch and Mare (2006), and Macy and van de Rijt (2006) have studied this process from the perspective
of residential segregation. Unless replaced by households similar to them, the racial/ethnic composition of a
neighborhood changes as households move out. There may also be consequences for other characteristics of
places such as poverty. Neighborhood turnover may exacerbate the negative consequences of climate change.
One of the “truisms” about migration is that it is selective. Migrants are positively selected from places
of origin. Those leaving particular areas are generally better off than those staying. So long as those places of
origin have positive qualities, those leaving will be replaced by other in-migrants. If those places of origin are
undesirable as potential destinations for other migrants, however, they will become increasingly disadvantaged
as out-migration continues. Climate change will have a deleterious effect on some places, and may serve to
advantage others (CCSP 2008). Depending on response, social inequality may increase as a result of dynamic
feedbacks in the system related to the selectivity of migration. Across multiple social and spatial scales, marginal
populations may be particularly likely to be affected by climatic events, partly because of their attachment to
marginal environments.
At the global level, projected impacts of climate warming show countries that are already at significant
disadvantage globally are the most likely to suffer from flooding associated with sea rise. Bangladesh is one
example. At a regional level, when Hurricane Katrina struck the southern coast of the U.S., already marginalized
populations were disproportionately affected. In New Orleans, the lower ninth ward was devastated and recovery
has been extremely slow. The contrast with Bourbon Street is stark. In the examples just given, the joint