5.3.3.3. Adaptation Options
Of all the systems that are sensitive to climatic change, the cryosphere may
be the most vulnerable; no adaptation measure can counter the disappearance
of snow and ice in an environment that is likely to experience more frequent
episodes of above-freezing temperatures than at present. In very restricted
situations, the use of snowmaking equipment may help to extend the skiing season
in particular areas, but this solution is expensive, and its environmental impact
has not been fully evaluated.
In terms of water resource management, technological measures-including land-use
criteria and erosion control, reservoirs and pipelines to increase the availability
of freshwater supply, and improvements in the efficiency of water use-can be
envisaged. Socioeconomic options should include direct measures to control water
use and land use, as well as indirect measures such as incentives or taxes;
institutional changes for improved resource management also may be needed. Specific
examples of possible options include supplementing rain-fed agriculture with
irrigation; water-conserving irrigation practices; enhanced coordination of
surface and groundwater management; changes in cropping patterns; watershed
management; structural and nonstructural flood-control management; and reallocation
of water resources among water-use sectors and among nations.
5.3.4. Coastal Zones
Coastal zones are characterized by highly diverse ecosystems that are important
as sources of food and habitats for many species. In many areas in Europe, population,
economic activity, and arable land are concentrated in coastal zones, which
has led to a decrease in their resilience and adaptability to variability and
change. Some coastal areas-such as much of The Netherlands, the fens in eastern
England, and the Po River plain (Italy)-already are beneath mean sea level;
many more areas are vulnerable to flooding from storm surges. Fixed, rigid flood
defenses and sea-level rise already are causing "coastal squeeze" (i.e., a decline
in intertidal coastal habitats).
Sea-level rise and possible changes in the frequency and/or intensity of extreme
events-such as temperature and precipitation extremes, cyclones, and storm surges-represent
consequences of climate change that are of most concern to coastal zones. Except
for sea-level rise itself, there currently is little understanding of the possible
interaction of different aspects of climate change in the coastal zone. Other
possible changes in climate could be costly. In The Netherlands, the costs of
protection against an adverse 10% change in the direction and intensity of storms
may be worse than the costs of a 60-cm rise in sea level (Peerbolte et al.,
1991; IPCC 1996, WG II, Chapter 9).
Under the IS92a scenario, global sea level is projected to rise by about 5
mm/yr (with an uncertainty range of 2-9 mm/yr). This increase is two to five
times the rate experienced over the past century. Regional and local sea-level
rise will not necessarily be the same as the global average because of vertical
land movements (glacial isostatic rebound, tectonic activity, subsidence) and
possible changes in ocean water characteristics (oceanic circulation, wind and
pressure patterns, ocean water density). Other climatic change in Europe is
uncertain. An increase in precipitation intensity seems likely, increasing the
flood risk in low-lying coastal areas.
Without adaptation, a rise in sea level would inundate and displace wetlands
and lowlands, erode shorelines, exacerbate coastal storm flooding, increase
the salinity of estuaries, threaten freshwater aquifers, and otherwise impact
water quality. The impacts would vary from place to place and would depend on
coastal type and relative topography. Areas most at risk would be tidal deltas,
low-lying coastal plains, beaches, islands (including barrier islands), coastal
wetlands, and estuaries. Tidal range also is a key factor: In general, the smaller
the tidal range, the greater the response to a given rise in sea level. This
pattern suggests that the Mediterranean and Baltic coasts, with their low tidal
range, may be more vulnerable to sea-level rise than the open ocean coasts.
Examples of susceptible coasts include the Rhone, Po, and Ebro deltas (Jimenez
and Sanchez-Arcilla, 1997; Sanchez-Arcilla and Jimenez, 1997). These areas already
are subsiding because of natural and sometimes human factors, and they are sediment-starved
as a result of changes in catchment management. For example, the Ebro delta
has lost 97% of its sand supply since the 1950s. Reduction or loss of these
areas would impact important agricultural and natural values. Many of Europe's
largest cities-such as London, Hamburg, St. Petersburg, Thessaloniki, and Venice-are
built on estuaries and lagoons (Frasetto, 1991). Such locations are exposed
to storm surges, and climatic change is an important factor to consider for
long-term development. In Venice, a 30-cm rise in relative sea level this century
has greatly exacerbated flooding and damage to this unique medieval city; permanent
solutions to this problem are still being investigated. Beaches tend to erode
given sea-level rise, which destroys a valuable resource and exposes human activities
landward of the beach to increased wave and flood action. Intense recreational
use of beaches in many coastal areas, particularly around the Mediterranean,
makes this erosion a particular problem; some response to such changes often
is essential. In higher latitudes, gravel beaches are more common than sand
beaches (Carter and Orford, 1993). Gravel beaches often provide an important
coastal protection function, which sea-level rise may disrupt.
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