14.2.3.1. General Impacts

Information on areas of land loss in several countries of Latin America as a result of sea-level rise is synthesized in Table 6-5 of the IPCC Special Report on Regional Impacts of Climate Change (IPCC, 1998). Fishing production is a sector that would suffer as a consequence of sea-level rise. Along the Central American coastline, sea-level rise will affect infrastructure, agriculture, and natural resources, as well as potentially exacerbate coastal erosion and salinization of aquifers and increase flood risks and the impact of severe storms (Campos et al., 1997; MINAE-IMN, 2000).

Chapter 6 of the Special Report identified information on the economic cost of sea-level rise in Latin America as assessed by Saizar (1997) and Olivo (1997) for the Uruguayan and Venezuelan coastlines, respectively. Saizar (1997) assessed the potential impacts of a 0.5-m sea-level rise on the coast of Montevideo (Uruguay). Given no adaptive response, the cost of such a rise in sea level was estimated to be US$23 million, with a shoreline recession of 56 m and land loss of 6.8 ha. Olivo (1997) studied the potential economic impacts of a 0.5-m sea-level rise on the coast of Venezuela. At six study sites, she identified land and infrastructure at risk—such as oil infrastructure, urban areas, and tourist infrastructure. Evaluating four scenarios, Olivo (1997) suggests that Venezuela cannot afford the costs of sea-level rise, either in terms of land and infrastructure lost under a no-protection policy or in terms of the costs involved in any of three protection policies.

Coastal wetlands in the region endure the impact of population growth, expansion of the agricultural activity, and land-use changes.

Observed sea-level rise at the local or regional level in Latin America could be greater than the global average value (Field, 1995; Codignotto, 1997; Kjerve and Macintosh, 1997). Negative trends in river streamflow along the Patagonian coast may result in reduction of sediments toward deposition areas. Coastal erosion would be affected by this effect as well as increased sea level (Codignotto, 1997; Kokot, 1999).

14.2.3.1.1. Mangrove ecosystem

The response of mangrove forests to changes in sea level within 50-100 years under climate change conditions is complex and controversial; it depends on physiography as well as ecological and biological factors (Villamizar, 1994; Ellison and Farnsworth, 1996; Ewel and Twilley, 1998; Rull et al., 1999).

The land-building function of mangrove vegetation has very important implications in coastal management because it works as a natural barrier to protect adjacent agricultural land by reducing erosion caused by wave action, tides, and river flow. This is important for shallow estuaries that are prone to flooding, especially where the land is below sea level (Twilley et al., 1997; Villamizar and Fonseca, 1999).

In the tropical Americas, the loss of coastal forests, mainly mangroves, occurs at a rate of approximately 1% yr^-1. The rate is much faster in the Caribbean—approximately 1.7% yr^-1 (Ellison and Farnsworth, 1997). Because most commercial shellfish and finfish use mangal for nurseries and refuge, fisheries in mangrove regions are declining at a similar rate as mangrove communities (Martínez et al., 1995; Ewel and Twilley, 1998).

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