These areas are already vulnerable to weather-related disasters such as typhoons, flooding, and cold spells. Drought too can be a problem, particularly in the south. All of these weather variables could change, particularly if, as computerized climate models suggest, global warming affects the strength and location of monsoons. If the monsoons shift northward, for example, the rainfall in northern Vietnam would increase. In the south, meanwhile, water availability would probably decline as warmer temperatures encourage evaporation losses.
Agriculture is the most vulnerable sector of the economy.
Rice is the main food crop and contributes significantly to the national economy, particularly since increased production in recent years has turned Vietnam into one of the world s major rice exporters. The nation s fertile agricultural lands, located in river basins and dependent on irrigation, are highly vulnerable to fluctuations in water levels. The Cuu Long Delta in the south already experiences frequent droughts and, every seven years or so, severe flooding. The flow of the great rivers that bring water to Vietnam s farmlands would be affected by changes in temperature and rainfall, as well as by measures taken by neighbouring nations in response to water shortages. This could result in lower crop yields and growth rates, the weakening or extinction of particular crop species, increased activity by pests and viruses, and a loss of soil fertility.