Global Warming, Sea Level Rise, and Saltwater Intrusion: Some Management Considerations

Long-term and short-term global temperature fluctuations influenced human cultural development prior to the mid-19° Century. Now evidence suggests that human activities may be altering the earth\u27s global temperature. By rapidly adding to the atmosphere large amounts of gases opaque to long-wave (thermal) radiation to the atmosphere, such activities may be enhancing the earth\u27s natural greenhouse effect . Spatial zero-dimension, one-dimension, and General Circulation computer models have been developed which quantify such parameters as atmospheric C02 concentrations, surface albedo and water vapor. These models then attempt to simulate present atmospheric circulation patterns and climate conditions and use the results to project future conditions. The results are used to suggest possible future regional climate scenarios. A global rise in temperature of 1.5-4.5°C by 2050 is predicted. Sea levels may be expected to rise by thermal expansion of ocean surface layers as warmer surface temperatures decrease water density, and by the addition of alpine glacial meltwaters. A rise of 15-75 cm by 2050 may be expected. Coastal areas will be impacted by beach erosion, wetland loss, complete inundation, and saltwater intrusion. Saltwater intrusion is a major concern of coastal communities and further intrusion can be anticipated in the coastal aquifer systems of southeastern Florida and the Keys where surface elevations are low. As population densities increase, greater demands will be placed on already stressed potable water resources and supplies. Although the degree to which projected effects will impact upon water resources is uncertain, it is certain that impacts will occur. A systems approach rather than separate responses to coastal zone management is the most flexible approach to the control of, and adaptation to, saltwater intrusion. Such an approach includes both physical structures, such as aquifer recharge, pumping configurations, well relocations, salinity control structures, and the Federal, state and local legislative policies already in place. A combination of these viable approaches needs to be considered now and the choices included in future development plans