sustainable development 20 years on from the ... - José Eli da Veiga

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Although the Central American region is privileged in terms of average water availability, water
distribution among countries, regions and in the Pacific and Atlantic watersheds is highly uneven, with
wide variations both during and between <strong>years</strong>. This, coupled with rainfall, causes flooding to alternate
with periods of severe drought. Population growth could drive up water demand by nearly 300% by <strong>20</strong>50
and by more than 1,600% by 2100 under a trend scenario without conservation measures and without
climate change. With climate change, demand could increase by a further 24% under the trend scenario
for GHG emissions (IPCC scenario A2). At the same time, the total availability of renewable water
resources could fall by approximately 60% by the end of this century under scenario A2 compared with
current availability. Unless adaptation and conservation measures are taken, changes in demand and
availability, coupled with climate change, could lead to water use intensity similar to that of Egypt and
some countries of the Arabian peninsula today (ECLAC, <strong>20</strong>10b).
Many climate change problems will be associated with changes in water resource availability and
the resulting effects on hydroelectric power generation, drinking water supply and water use for irrigation
and other production sector activities, including manufacturing and mining (ECLAC, <strong>20</strong>10a). This raises
the need to consider possible climate variations when designing and implementing infrastructure projects
and when formulating water resource management policies and strategies, so that new infrastructure is
resilient enough to withstand the risks of disasters.
7. Protection of coasts, oceans and seas
Approximately 50% of the region’s population and many of its <strong>development</strong> activities are concentrated
within 100 kilometres (km) of the coast. This exerts strong pressure on coastal ecosystems and poses a
threat to the resources that ensure people’s survival in coastal areas (UNEP, <strong>20</strong>07).
The region’s oceans receive high pollutant loads and face a number of threats as a result: 86% of
wastewater (up to 90% in the Caribbean) enters rivers and oceans untreated; eutrophication caused by
land-based sources of nutrient pollution; inadequate wastewater treatment in cities; salinization of
estuaries owing to declining flows of freshwater; and the introduction of invasive alien species through
the uncontrolled release of ballast water from vessels. Another threat is acidification of oceans as a result
of CO 2 concentrations, affecting fisheries and coral reefs (UNEP, <strong>20</strong>10b).
In the past 10 <strong>years</strong>, the region’s marine and coastal ecosystems have contributed between 15%
and 30% of the world’s total fish supply. The west coast of South America, the west coast of Central
America, the Gulf of Mexico and the Caribbean coasts are the most degraded coastlines in Latin America
and the Caribbean (UNEP/CATHALAC, <strong>20</strong>10).
Some of the region’s most degraded ecosystems are mangroves, wetlands and coral reefs. These
coastal habitats play an important role in protection against weather-related risks, stabilization and other
ecosystem services, as well as in the <strong>development</strong> of ecosystem-based economic activities. The ecosystem
services provided by mangroves include protecting marine rangelands and reefs by filtering pollutants;
contributing to the catch of economically valuable fish and crustacean species by providing nesting and
nursing grounds; reducing coastal erosion; and offering high recreational value. In addition, they play a
key role in adaptation to climate change by acting as a buffer against extreme weather events (Granek and
Ruttenberg, <strong>20</strong>07) and in climate change mitigation by absorbing up to four times more carbon dioxide
than terrestrial forest (Crooks and others, <strong>20</strong>11; Nellemann and others, <strong>20</strong>09). However, they are at risk
because of urban and tourist <strong>development</strong>, aquaculture, invasive alien species, pollution and changes in