Vulnerability, Impacts and Adaptation of Coastal Zones to Global Change - Vulnerability of Coastal Ecosystems and Adaptation - page 135

social cohesion, economic resources and their diversity, political
organization and living conditions. The concept of resilience, which
means the capacity of an organism or a system to adapt to a changing
environment and to maintain its essential function, identity and
structure, is also often used instead of adaptive capacity although they
are different concepts. We also speak of risk when faced with an
uncertain hazard (a dangerous phenomenon or process) for a system or
geographical zone where there are stakes that can be human, economic
or environmental. Risk is often represented as a probability of
occurrence of hazardous events or trends multiplied by the
consequences if these events occur.
Regarding the effect of cumulative global changes on coastal
zones, the question is more complex. Due to the fact that coastal zones
are very dynamic regions where several drivers interact originating a
large variety of different effects, attributing an origin to the impacts
observed is difficult. The main driver that determines the dynamic of
the anthropogenic global changes and their impacts on the coastal
zones is socio-economic development and population growth.
According to estimates for the year 2000 [MCG 07], the low elevation
coastal zones, which only constitute 2% of the Earth's surface above
sea level, shelter 10% of the world's population, corresponding to
approximately 610 million people and 13% of the global urban
population (about 360 million people). On a global level, about 65%
of the world's cities with more than 5 million inhabitants, the majority
of small island states and deltas with a high population density are
situated in low elevation coastal zones.
In coastal towns, the risk of losses due to flooding, associated in
some regions with subsidence, is currently increasing significantly due
to increases in population and exposed assets, to urbanization and to
the construction of infrastructure. According to Hallegatte et al.
[HAL 13], the annual losses due to floods in the 136 most populous
coastal cities were, in 2005, in the order of 6 billion dollars. Without
new, efficient adaptation measures in these cities, the annual
cumulative losses would reach more than 1,000 billion dollars in
2050. Even with adaptation measures, assuming a constant flooding