Climate Change Impact Models Research Articles

THE ROLE OF MOISTURE TRANSPORT BETWEEN GROUND AND ATMOSPHERE IN GLOBAL CHANGE

▪ Abstract Projections of the effect of climate change on future water availability are examined by reviewing the formulations used to calculate moisture transport between the ground and the atmosphere. General circulation models and climate change impact models have substantially different formulations for evapotranspiration, so their projections of future water availability often disagree, even though they use the same temperature and precipitation forecasts. General circulation models forecast little change in tropical and subtropical water availability, while impact models show severe water and agricultural shortages. A comparison of observations and modeling techniques shows that the parameterizations in general circulation models likely lead to an underestimate of the impacts of global warming on soil moisture and vegetation. Such errors would crucially affect the temperature and precipitation forecasts used in impact models. Some impact model evaporation formulations are probably more appropriate than those in general circulation models, but important questions remain. More observations are needed, especially in the vicinity of forests, to determine appropriate parameterizations.

Role of hydrological forecasts and river flow modelling in rational agricultural water management in the perspective of a climate change — A case study of the Rivers Upper Nile and Niger

An international scientific conference under the auspices of WMO, UNEP and ICSU on the role of CO 2 and other greenhouse gases in climate variation made a statement that, if the concentration of CO 2 in the atmosphere doubles in the near future as present trends indicate, the global mean surface temperature would increase by 1.5–4.5°C. The paper discusses the impact such a climate change may have on water resources and on their management in agriculture. It stresses the importance of the possible increase in variance and frequency of extreme climatic events and subsequent water yield. It further outlines the ways of exploring the consequences of such development by using hydrological and water management models. It also proposes that real-time hydrological forecasting systems, able to produce forecasts with long, medium and short lead times, are one of the most effective measures to offset possible negative effects of the climate change, by increasing the effectiveness of storage management. These propositions are documented by means of case studies from developing countries using models on the River Nile, in particular in the basin of Lake Victoria, and of a hydrological forecasting system on the River Niger. It is proposed that it is important to develop a simulation model of the whole River Nile, together with a real-time forecasting system on the river in order to operate efficiently existing and future storages. Modelling of climate change impact on the water yields of River Niger is also discussed.