Global warming could have serious consequences for agricultural production. Some effects may be beneficial but many would be adverse. Not only might yields and quality be affected but crops may have to be grown in different locations as climate conditions alter.
Agricultural production is likely to be affected by:
Sea level rise presents a major threat to Vietnamese agriculture.
Agricultural lands are concentrated along the coast in the two major deltas. Sea level rise threatens these regions and would drastically affect their peoples. Arable land might be reduced, some areas could become salinated and people may have to be relocated, increasing pressure on resources in neighbouring regions.
Analysis of the response of crop yields to past climate fluctuations shows that the productivity of the food crops and cereal crops of Vietnam varies greatly. Crop productivity variations in the north are more marked than those of the south and cereal crop yields vary more distinctly than those of rice.
Crop losses are often caused by an accumulation of factors.
The most serious losses are caused by typhoons (20-50%), although the area affected tends to be limited. Droughts, long periods of sunshine in winter and water-logging are also important (10-30%) and affect a wider area. Cold spells, dry spells and dry-hot winds causes less severe damage (5-20%) and affect a limited area. In the past, rainfall has been a more important factor than temperature.
Studies by Vietnamese scientists have shown that the northern region, especially the Red River Delta, is the most sensitive to present-day climate variability. Rainfall fluctuations are strongest in this area and drought and flooding frequently limit crop yields.
In the north of Central Vietnam, meteorological disasters such as storms have their greatest impact on agriculture. There is concern that the typhoon season may increase in severity and become more prolonged in the future. This will have serious consequences for the region, increasing wind damage and flooding.
In upland regions, the rise in temperature may enable cultivation at higher elevations, although crops grown at present may be lost completely in some areas.
The vulnerability of southern regions is likely to rise as global warming develops. Where climate used to be stable, and impacts on agriculture less frequent, climate change is now occurring at a higher rate.
The increased incidence of drought in the south of the country as rising temperature increases evaporation water loss would be a major impact of global warming. The range of crops that can be grown may be reduced. Pest outbreaks may become more frequent as temperature and humidity increase in the winter months.
Taking future trends into consideration, the Mekong Delta and the coastal areas in the north of the central region are considered the most vulnerable to the changes expected to occur as a result of global warming.
Further research is necessary to define the likely impacts of global warming on Vietnamese agriculture in greater detail and to identify the most appropriate means of adapting food production to the changing environment and ensuring sustainable yields.
Based on material provided by
Dr Nguyen Huu Ninh, Director, Center for Environment Research Education and Development
Dr Hoang Minh Hien, Hydrometeorological Service