Cover page |
by R. Gommes and J. du Guerny,
Sustainable Development Department
and F. Nachtergaele and R. Brinkman
Food and Agriculture Organization of the United Nations
THIS SD-DIMENSIONS SPECIAL addresses issues related to the potential
impacts of sea level rise on the world's coastal populations and agriculture.
This is a "global" study mostly based on national data.
The literature confirms that indirect effects of sea level rise, as
well as the potential impact of extreme events, may be more significant
than direct effects in the future. In the absence of an accepted methodology
for building long-term scenarios, two approaches are explored here: an
analysis of a large database of extreme events that have occurred over
the last 100 years, and an analysis of population statistics in relation
to a national Vulnerability Index based on physiographic features and
Recent historical data are examined to identify trends that could be
extrapolated into the 21st century. This is achieved by separating
those factors that are more specifically associated with the oceans -
tropical cyclones, tsunamis - from other, more land-bound or population-bound
disasters, such as droughts and epidemics. Despite the limitations of
the data sets, some trends do emerge, but they do not necessarily
point in the direction of greater property and population losses in
the future owing to sea-caused disasters. Rather, they indicate that
difficulties - independent of the global changes - will be relatively
larger on land than along the coasts, and that the major component of
life and property losses are associated with levels of economic development.
The "national vulnerability index" confirms that vulnerability - if
considered at a global scale - varies considerably, over several orders
of magnitude. In addition, the index exhibits a marked positive skew.
Combined with changes in population concentrations and the positive
skew of many climatological elements (such as wind and rainfall), as
well as sea-level rise itself, this indicates that relatively greater
disasters are likely.
The paper stresses that both the impacted system (population and coastal
agriculture) and the extreme physical factors have their own dynamics,
and that those dynamics are not independent. Some thought is given to
the notion of "shock-waves", i.e. the repercussions at some distance
from the rising seas.