Sustainability and policy - Climate Change: Biological and Human Aspects - page 516

Leaving aside temperature, in terms of human global distribution, sea-level rise
is arguably one of the factors that will incur both impacts and adaptation costs.
Worldwide some 70% of the global population live in coastal areas or near rivers. A
significant proportion of these could potentially be affected by sea-level rise and/or
possible flooding due to increased (seasonal?) precipitation. The IPCC (2001b) estim-
ate that in Western Europe alone in 1990 some 25.5 million people were exposed to
coastal flood risk and that of these roughly one in 1000 actually experienced flooding.
Assuming no adaptation the IPCC consider that between half as much again to 90
times that number might be affected by the 2080s (see also section 7.3.3 and Table
7.1). The degree of uncertainty reflects the combination of uncertainty in the pro-
portion of the population with a degree of flood-proofing and the uncertainty in the
IPCC's forecasts. However, either way this represents a significant cost.
Adapting to climate change-related impacts, such as flooding, does not mean
reducing risks or flooding to zero. This is for two reasons. First, to eliminate all risks
and flooding would be the most expensive option and is likely to be too expensive for
society/communities to condone. Second, not all flooding does significant damage
or incurs a permanent cost. For example, you may be aware of a street near you
that becomes difficult to traverse after a heavy sustained downpour but then drains
comparatively quickly. There are also land areas that are naturally prone to, and
might even benefit from, occasional flooding. Marshes and other wetlands are obvious
examples. Finally, extreme flooding for some will be a very rare event and proofing
everyone against these may be too expensive. In these cases 'soft' measures (such
as allowing fields and parks to flood) as opposed to physical infrastructure (flood
barriers) may be more economical. It is a question of assessing costs and risk.
There are two key problems of assessing costs and risks with climate change. First
there is the fundamental assumption that the risk and cost assessments are accurate.
The 2005 example of Hurricane Katrina and New Orleans is illustrative. The 1998
proposed protection plan Coast 2050 had a potential cost of some US$14 billion. It
did not get implemented as nobody was prepared to pay; the risk or hazard was not
considered to be worth the cost. It was a gamble that such an event would not happen.
Yet following Katrina the economic losses were in excess of $125 billion. (We will
return to this shortly.) The second problem is that climate change is by definition
dynamic and not static: past experience cannot be used as a guide to the future.
For example, most of the New Orleans levees breached by Katrina were designed
to deal with floods that occur once every 30 years or so. Now, notwithstanding
whether this itself was an appropriate judgement of the degree of protection required,
given the change in strength and frequency of extreme weather events due to global
warming (Chapter 6), basing safety decisions on past criteria will be unreliable
whereas including forecasts of future change would be prudent. That there is and will
be global warming is not a gamble, even if the exact rate and extent of this warming
are not exactly certain.
One of the countries that has historically spent the most on sea protection per
length of coastline is The Netherlands. Quite simply this is because it is a low-lying
country, with some 60% below sea level, and it is also a wealthy Western European
nation. In addition, some 70% of its gross national product is earned in its low-lying
areas and this provides a certain financial motivation. Indeed, the country is due to