拉丁美洲海岸侵蚀的现状英文文献和中文翻译(4)
Figure 3. Population and LECZ by continent and for Latin America. Because the socioeconomic conditions of Latin America vary between countries, and because the cost of living and free market conditions are not the same, it is difficult to establish an economic basis for comparison between Latin American countries. For this reason it was decided to use the human development index (HDI) proposed by The United Nations Environment Programme (UNEP/RSP, 2006). The HDI is an index of socioeconomic development that allows comparisons to be made across regions. UNEP considers HDI = 0.7 threshold as the limit of countries with high human development. Half the countries have a relatively high HDI: Chile, (highest), is followed by Argentina, Uruguay, Cuba, Panamá, Mexico, Costa Rica, Venezuela, Peru and Brazil (lowest) (Figure 5). In contrast, HDI in the remaining 10 Latin American countries has slowly increased and is still suboptimal. Overall, HDI in Latin America has increased slowly and to a relatively low level, but it has reached much higher values in comparison with HDI estimates for the world as a whole. Figure 4. Relative and total population relative to the national total in each country, population density and LECZ by country for Latin America. COASTAL HAZARDS AND RESILIENCE “Vulnerability” refers to the weakness of the exposed system (e.g., the number of people killed per million exposed) and “resilience” is the capacity of a system to experience shocks (a disturbance) while essentially retaining the same function, structure, and feedbacks (Holling, 1973; Walker et al., 2006; Escudero et al., 2012). A resilient shoreline reduces population risk because vulnerability is reduced. The coasts of Latin America are exposed to a wide range of hazards that affect the coastal population.
Here we explore some of the frequent and intense hazards faced (tropical cyclones/hurricanes, sea level rise, ocean acidification, earthquakes and tsunami events), and analyse how population vulnerability and coastal resilience determine local risk. In order to evaluate the most frequent hazards for coastal zones in LatinAmerica, a database was built using information of cyclones (Knapp et al., 2010), sea level rise (NOAA, 2014), acidification (Halpern et al., 2008), earthquakes and run up from tsunami (NGDC / WDS, 2014). In the following sections some of the most common, documented, natural hazards which affect Latin America are presented. Figure 5. Evolution of the human development index (HDI) over time for each Latin American country. Cyclones Tropical cyclones, called hurricanes in North America, when the wind speed is greater than 64 kn (120 km/h), occur in many regions and affect most tropical coasts (Figure 6a). Between 1970 and 2009, these hydrometeorological events claimed 789,000 lives and caused great economic damage in the world (Peduzzi et al., 2012). Because of the coastal population growth, all regions have increasing vulnerability to tropical cyclones. Nevertheless, the risk (exposure times vulnerability) has been reduced in some regions because the vulnerability (number killed per million exposed) is lower. This is the case for North America, where the tropical cyclone/hurricane risk has declined in spite of an increasing coastal population. In Central and South America, as well as Asia, vulnerability has decreased dramatically since 1970, because of improved early warning systems, the construction of shelters and the reforestation of coastal areas (Paul, 2009). Sea Level Rise Trends Based on tide station measurements around the world, the Intergovernmental Panel on Climate Change (IPCC, 2007) Report estimates that over the past century, the global sea level rise has ranged from 1.7-1.8 mm/yr (IPCC, 2007). Tide stations measure Local Sea Level, which is the height of the water along the coast relative to specific, stable, vertical points (or bench marks) on land. However, the measurements at any given tide station reflect sea level rise as well as vertical land motion, such as subsidence, glacial rebound, or large-scale tectonic motion. Because these two levels are changing, the land-water interface can vary spatially and temporally and must be defined over time. Local sea level trends may differ greatly from the average rate of global sea level rise, and can vary widely from one location to the next. For instance, in some places in the north of the Gulf of Mexico (Figure 6b) significant subsidence is occurring and so relative sea level trends show an increase of over 10 mm a year, while areas of Chile reflect a decrease in relative sea level because the land is subjected to regional uplift, related to tectonic factors and subduction effects (Baker et al., 2013). Relative Sea Level Trends are critical for many coastal applications, including coastal mapping, marine boundary delineation, coastal zone management, coastal engineering and sustainable habitat restoration design. These values focus on relative sea level trends, computed from the monthly averages of hourly water levels from specific tide stations, called monthly mean sea level. Figure 6. The most frequent and intense hazards for the coastal zones of Latin America. (a) tropical cyclones (from Knapp et al., 2010); (b) sea level rise (IPCC, 2007); (c) ocean acidification (after Halpern et al., 2008); and (d) earthquakes and tsunami runup (NGDC/WDS, 2014). Acidification Changes in CO2 concentration alter the aragonite saturation state (ASS) of the ocean, among other chemical properties of seawater. As ASS levels drop, the ability of calcifying species such as corals and shelled invertebrates to create calcium carbonate structures declines (S22). The global distribution of 源:自*优尔`%论,文'网·www.youerw.com/