Trends in Land Degradation in Latin America and the Caribbean, the Role of Climate Change

Abstract

Latin America has a rich reserve of genetic resources. About 40% of the known living species are present in this Region. The continent represents an important reserve of cultivated land and fresh water. About one third of the forest of the world lives in their important tropical and temperate biomes, much of them are in pristine condition. Despite its genetic richness, important deforestation has affected mainly coastal ecosystems, settlement of the most part of its population. Originally, this continent had 6.93 millions km² of forests. At present only 3.66 of its original forest coverage remain. Present rate of forest loss is 15,000 km² yr⁻¹, that is to say, almost 3 ha per minute. About 45% of croplands in South America and 74% in Meso-America are degraded. The arid lands are threatened by desertification and very often by droughts. Both phenomena have high social costs pushing millions of people to move to cities, creating social pressure in urban areas. This is one of the sources of crime increase and political instability in many countries. At present, the tropical rain forest continues to be cleared, mainly using fire, to open lands for annual crops and pastures. There are some biomes like temperate forest in Chile and Argentina, the Mata Atlantica in Brazil, the dry subtropical forest of the Chaco, that have been reduced to small patches.

The main source of human pressure on the environment comes from unsound agricultural practices and interventions on natural ecosystems to extract goods and services. In addition, climate has been fluctuating forcing important landscape changes in the last thousand of years. Climatic trends are evident in extensive areas of the continent. Temperature in tropical Andes shows a significant warming of about 0.33°C per decade since the mid-1970s. Minimum temperature has increased as much as 2°C in some coastal areas. In the South Western Pacific coast, rainfall has shown a clear negative trend throughout the 20^th century. A contrary trend has been observed in the Atlantic coast of Argentina and Southern Brazil. Climatic variability seems to be increasing, making more frequent extreme climatic events of drought and floods. In the overall continent a rapid reduction in the permanent ice bodies is observed, mainly Andean permafrost and glaciers, which moved upward their lower front about 300 m or more in a century. Main biomes of the continent are subjected to different natural and human drivers or pressure. Among the most threatened biomes are the Caatinga in Brazil, the Amazon rain forest, temperate forest of the Patagonia, the arid and semiarid Sclerofylous forest and highlands of Puna.

Increasing climatic hazards are forcing farmers to opt low input agriculture in order to reduce economic risk. This leads to a marginal agriculture, associated with low yields and income, and consequently, social deterioration and very often, the primary cause of massive migrations. In some areas, farmers will never be able to adapt to these conditions at the required speed. Currently, prices of agricultural products are at the lower limit to support reductions on yields, so, farmers are in an extremely vulnerable condition.