Though the thin strip
of coastal land at the continental margins and within islands accounts
for less than 5% of Earth’s land area, 17% of the global
population lives within the coastal systems as defined in this chapter,
and 39% of global population lives within the full land area
that is within 100 kilometers of a coast (CIESIN 2000). Population
density in coastal areas is close to 100 people per square kilometer
compared with inland densities of 38 people per square
kilometer in 2000. Though many earlier estimates of coastal populations
have presented higher figures (in some cases, near 70% of
the world population was cited as living within the coastal zone),
previous estimates used much more generous geographic definitions
of the coastal area and may be misleading (Cohen 1995;
Tibbetts 2002). That we have used a narrower definition and refined
the coastal population numbers downwards in no way implies
that coastal systems have lesser importance to humans—on
the contrary, this assessment underlines the central extent to
which human well-being is linked to the health and productivity
of coastal systems