Climate change, species extinction, water scarcity 329Extensive redistributions of urban populations also provide the opportunity for
implementing different transportation modes, such as diverse flexible people-
movers, small raised monorails, horizontal ski-transport technologies, dual-level
shop-front sidewalks, and other methods for relatively short- and medium-
distance movement in metro areas.
Climate-change specialists also point to an expected increase, both in size
and frequency, ofextreme weather eventssuch as intense winds and heavy precipi-
tation. Floods and hurricanes/cyclones tend to cause especially serious problems
in urban regions, because of the density of both people and solid human struc-
tures like buildings, roads, and bridges. These structures carefully designed by
the engineer or architect for society typically have less give, less resilience, than
ahealthy wetland or natural area, so when confronted with a strong enough
force theybreak.
One solution against extreme-weather events is to build using both nature
and engineering (including bioengineering), and nature and architecture (bio-
philic design, including green roofs). Another approach is a higher investment
priority in identifying, and placing nature in every location likely to be heavily
impacted by extreme-weather events. Steep slopes and narrow floodplains would
become building-free, wetland vegetation would cover low areas, and shrubby
strips would cover riparian zones. Minimizing abrupt boundaries and provid-
ing multiple lines of defense are additional strategies against extreme-weather
events. For example between deep water and uplands, protected gentle slopes,
shallow water bodies, wetlands, and natural ridges all help to absorb or dissipate
disruptive energy pulses (Costanzaet al.2006).
Climate-change scenarios offer an opportunity for urban regions to address
many large knotty issues. Reducing carbon-dioxide production calls for citizens
and cities alike to change. Implementing solutions to temperature increase, sea-
level rise, and extreme-weather events does too. Educating a region’s residents of
theproblems and laying out possible solutions is a key step. Then, capitalizing
on the resulting expectation of change, a broader, bigger set of urban-region
issues can be addressed than simply climate change.
Species extinction
Species extinction is forever, one of those rare phenomena, like death,
that is irreversible. Habitat loss is the major cause, though habitat degradation
and perhaps fragmentation are significant overall (Wilson 1992, Wilcoveet al.
1998, Groomet al.2006, Primack 2004, Lindenmayer and Burgman2005). Loss of
isolated habitats, such as on islands and in lakes, and of tropical rainforest that
holds about half the Earth’s species, has been the core of species extinction.