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DESERTIFICATION, DROUGHT AND THE GLOBAL ENVIRONMENT
Professor Robert Balling, Arizona State University, USA: Prof. Balling spoke about the inter-relationships between the global climate system, drought and desertification, including the impact of desertification on climate change and global warming. The first part of his presentation addressed what is known about climate in the drylands. The major characteristic of dryland climates is their unusual variability. Precipitation varies from season to season and year to year and consistent cycles are not typically found in dryland rainfall data.
He then addressed the question of whether dryland droughts can be predicted. Dryland precipitation levels are linked statistically to sea surface conditions, the impact of El Ni¤o and southern oscillation events, general atmospheric circulation patterns, solar patterns, volcanic eruptions, typhoons and hurricanes. At this point scientists understand what is driving the climate patterns in drylands and can predict the rainfall in seasons, if not in months.
Human activities have impacted the surface and atmosphere in drylands primarily by reducing vegetation cover through overgrazing and cultivation practices. He elaborated on the scientific debate on the relationship between a decrease in soil and vegetative cover and climate change. With regard to the greenhouse effect, he commented that drylands are not major emitters of greenhouse gases or major carbon sinks. Climate change is bad news for drylands where temperatures may increase by 2-5 degrees.
In the discussion that followed, Egypt commented on the role of drylands as a sink for greenhouse gases and the important issue of deserts as an emitter of particulates in the atmosphere. He stressed the point that no one country alone can do early weather forecasting that can predict drought. The UK mentioned the large areas of uncertainty in the links between climate and desertification. He added that the UK had commissioned a report on this subject and that he would make it available to other delegates.
Professor A.M. Imevbore, Obaferni Awolowo University, Nigeria: Prof. Imevbore spoke about desertification as a threat to the conservation and utilization of biodiversity. He emphasized the need to redefine desertification. He pointed out that desertification can be defined by vegetation cover, short savanna, woodlands, and by impact of human activity such as logging, reduced availability of water and reduction in woody biomass. He emphasized the importance of conserving biodiversity in the drylands and said that 64 out of 300 species of medicinal plants are located in the drylands and that the few existing plant species in the drylands serve multiple purposes. He also highlighted the importance of the tourism industry based on wildlife found in the drylands, such as Kenya. He concluded that there is need to conserve biodiversity and underlined the vast amount of research required to manage the drylands efficiently. These include availability of remote-sensing data for drought preparedness, strengthening of institutional structures for the management of wildlife, fauna and flora and the search for greater perenniality.
In the discussion that followed, Egypt emphasized that they should not redefine terms but use the definitions provided in Agenda 21. He also emphasized the need to distinguish between desertification and drought. The constraint of poverty in biodiversity conservation was also raised.
UNESCO (Habib Zebidi, Programme Specialist in Hydrology, Division of Water Sciences): Mr. Zebidi spoke on the effects of desertification on surface water and groundwater systems and on water availability and quality. He began with definitions of desertification and noted the fact that there are 6,100 million hectares of arid lands, home to one-fifth of the world's population, with Africa, the Arabian Peninsula and Australia as the regions most affected. He focussed on the characteristics of these areas. The first characteristic is that rainfall is limited and irregular, with the greatest variability of rainfall found in arid and semi-arid land. High sediment transport is a feature of surface flow, due to run-off fluctuations. Another characteristic is that groundwater is often found in these regions. The availability of water depends on the type of catchment system used. He noted the effects of desertification on groundwater systems. He also discussed surface run-off from flood waters and rain and the collection of this water with dams. He concluded by noting the potential for conflict over water resources in the event of drought and the need for national policies to distribute scare water resources. He also noted the possibilities of more violent flash floods due to the soil's lower retention capacity to absorb irregular rainfall.
In the discussion, Egypt cited facts on total water availability and experiments in more aggressive means to find fresh water, including from icebergs and deeply seated aquifers. Germany noted a case in Argentina where an artificial dam created micro-climatic change. Iran stated that there is a need to utilize traditional methods of scarce water development in arid and semi-arid areas.
UNEP (Dr. Norberto Fernandez, GRID Facility): Dr. Fernandez spoke about modern techniques for assessing the global environment, including satellite imagery, remote sensing and geographic information systems. He mentioned that sound management of the environment requires good assessment of situations, which, in turn, requires timely and reliable data and information. He explained that the transfer of data and information from the sectorial sources to the decision-making level is an on-going process. The Global Resource Information Database (GRID) has helped to bridge the gap between scientific understanding of earth processes and sound management of the environment.
He then explained the uses of geographic information systems (GIS) that can integrate data from different sources and add a spatial dimension, bringing flexibility into data analysis. Although GIS cannot give the real answer to the problem of desertification, it can help build hypotheses. He explained how the World Atlas of Desertification is an important contribution to the understanding of this issue and provides information in a clear, concise, geographically-referenced format. It shows interactions between socio-economic and environmental factors and helps governments and policy-makers to assess the scope of the problem, examine alternatives and decide on a course of action. The discussion on this presentation will take place on Tuesday.