LONG-TERM FORECAST: HOT AND DRY

LONG-TERM FORECAST: HOT AND DRY

A           Melting land ice in the Arctic is set to cause a global rise in sea levels, leading to disastrous effects for both man and wildlife. Many species worldwide are threatened with extinction, and low-lying islands and land masses will disappear entirely. But the havoc wreaked by the effect of greenhouse gases won’t be confined to just too much water, but the absence of it, as well. In other words, desertification. A decrease in the total amount of rainfall in arid and semi-arid areas could increase the total area of drylands worldwide, and thus the total amount of land potentially at risk from desertification.

B          Desertification is officially recognised as land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors including climatic variations and human activities. This degradation of formerly productive land is a complex process. It involves multiple causes, and it proceeds at varying rates in different climates. Desertification may intensify a general climatic trend, or initiate a change in local climate, both leading towards greater aridity. The more arid conditions associated with desertification accelerate the depletion of vegetation and soils. Land degradation occurs all over the world, but it is only referred to as desertification when it takes place in drylands. This is because these areas are especially prone to more permanent damage as different areas of degraded land spread and merge together to form desert-like conditions.

C            Global warming brought about by increasing greenhouse gas levels in the atmosphere is expected to increase the variability of weather conditions and extreme events. Many dryland areas face increasingly low and erratic rainfalls, coupled with soil erosion by wind and the drying-up of water resources through increased regional temperatures. Deforestation can also reduce rainfall in certain areas, increasing the threat of desertification. It is not yet possible, despite sophisticated technology, to identify with an acceptable degree of reliability those parts of the Earth where desertification will occur. Existing drylands, which cover over 40% of the total land area of the world, most significantly in Africa and Asia, will probably be most at risk from climate change. These areas already experience low rainfall, and any that falls is usually in the form of short, erratic, high-intensity storms. In addition, such areas also suffer from land degradation due to over-cultivation, overgrazing, deforestation and poor irrigation practices.

D               It is a misconception that droughts cause desertification. Droughts are common in arid and semi-arid lands. Well-managed lands can recover from drought when the rains return. Continued land abuse during droughts, however, increases land degradation. Nor does desertification occur in linear, easily definable patterns. Deserts advance erratically, forming patches on their borders. Areas far from natural deserts can degrade quickly to barren soil, rock, or sand through poor land management. The presence of a nearby desert has no direct relationship to desertification. Unfortunately, an area undergoing desertification is brought to public attention only after the process is well underway. Often little or no data are available to indicate the previous state of the ecosystem or the rate of degradation. Scientists still question whether desertification, as a process of global change, is permanent or how and when it can be halted or reversed.

E              But desertification will not be limited to the drylands of Africa and Asia. According to the environmental organisation Greenpeace, the Mediterranean will suffer substantially, too. If current trends in emissions of greenhouse gases continue, global temperatures are expected to rise faster over the next century than over any time during the last 10,000 years. Significant uncertainties surround predictions of regional