The Ganges Delta supports one the world's densest populations (1.1 billion in 143,998 sq. km). The Ganges Delta normally receives over a billion tons of sediment and 971 km³ of fresh water annually. However, the diversion of the Ganges River at Farraka Barrage has led to decreased fresh water and sediment flux into the delta. The negative effect so far has been the increase of saline-water intrusion in inland streams (that can extend up to 240 km inland) and subsidence that remains uncompensated by new sediments. The latter has been inferred to be as much as 2.5 cm/year in some parts of the delta (some 10 times the natural rate). These high subsidence rates, however, may be at least in part due to the rapid withdrawal of ground water from the delta itself. In the 1980s over 100,000 tubewells and 20,000 deep wells were sunk in the delta for fresh water supply that increased subsurface water withdrawal by six-fold in a relatively short time. The dire prognosis for potential inundation of sea in the Ganges Delta and loss of land and economic activity require drastic and expeditious actions. By the middle of 21^st century the relative sea level could locally rise by as much 1.8 m by the combined effect of accelerated subsidence and eustatic rise. The sea level could locally rise by as much as 3 m by the end of the century, with a loss of land to invading seas of up to 23% that supports 25% of the population and 25% of the current GDP of the nation.

　　If increase in greenhouse emissions go unabated and global temperatures continue to rise, increases in sea surface temperatures (SST) also may mean an increase in frequency and intensity of cyclones. The SST is, in effect, a major controlling factor for the frequency of tropical storms. An increase in global temperature of 1° to 2℃ is likely to spawn more cyclones, thereby multiplying the devastating effects on the coast. At present storm surges with tidal highs of up to 6 m over normal that can reach up to 200 km inland are associated with individual cyclones. This could conceivably worsen, if present trends are not reversed.

　　Egypt's Nile Delta differs from the Ganges Delta in that the Nile has been effectively dammed since the mid 1960s, allowing little fresh water and almost no new sediments into the delta. Most of Egypt's 57 million inhabitants live in the narrow fringe along the fertile Nile Valley and the Delta, only 4 % of the total land of Egypt. This makes the Nile Delta more densely populated than Bangladesh.

　　Since the completion of the High Aswan Dam on the Nile in 1971 the loss of replenishing sediments in the delta has led to greater shoreline erosion, which has increased five-fold at the river mouth. In places the shoreline retreats landward as much as 10 m per year. Lack of nutrient-rich Nile water has already nearly wiped out sardine fishery and led to increased salinization of soil within the delta. The projected sea-level rise in the delta of 1 m by the end of 21^st century is estimated to inundate as much as 15% of productive land that support 13% of Egypt's GDP.

　　Nearly 40% of the world's population is concentrated within 80 km of the coastline. In the developing countries up to two-third of the population is projected to live in coastal urban areas at the turn of the century, which will further increase the already overstretched demands for resources and services in the coastal zone. The problems of accelerated subsidence and deterioration of water resources exemplified by Bangkok are also common to many megacities along the coasts, such as Shanghai and Tianjin in China.

　　Bangkok has seen a burgeoning population increase in the recent decades, reaching to ca. 8 million in the year 1990. This has created increased demands for local resources and services. Greater fresh-water demands have meant withdrawal of ground water at an increasingly rapid rate. The depletion of ground-water acquifers has led to unprecedented rates of subsidence in some parts of the city, up to 10 cm/year subsidence has been measured downtown. These rates of subsidence have had detrimental impacts on the city's infrastructure. Deteriorating ground-water quality, damage to the city's drainage system and inundation during high tides are already evident. Since much of Bangkok lies about a meter above mean sea level, further subsidence could permanently flood large portions of the city by the middle of this century. Greater salt-water intrusion in acquifers, disruption of transportation, and backing-up of the drainage system, are all expected to become a severe problem under the scenario of unabated subsidence.

　　Small island nations, most of which are coral reefs and atolls, are in a special category where local subsidence may not be a significant threat, but because they are at or just-above sea level, the global sea-level rise due to greenhouse warming alone may pose a significant threat. Under favorable conditions, a healthy reef can grow fairly rapidly, keeping pace with sea-level rise of as much as 1 cm/year. The production of carbonate sediment associated with reef growth keeps the island in equilibrium with the sea level. However, when the reef has been damaged extensively and the ecosystem is stressed it may not be able to keep pace with sea-level rise. Such may be the case with many mid ocean islands where poor fishing practices may have severely damaged the reef. The Maldives and Laccadives provide examples of such vulnerable small island nations in the Indian Ocean and the Marshall Islands in the Pacific.

　　In their report to the world community, IPCC (1990) emphasized the urgency for maritime countries to undertake advance planning for adaptive strategies to potential sea-level rise in order to avoid adverse impacts - an opportunity that may be lost by inaction. Impacts of accelerated sea-level rise include the threat of coastal inundation and erosion, changes in the salinity of the economically important coastal estuaries and lagoons, loss of wetlands, and intrusion of salt water into fresh-water acquifers. Wetlands are especially vulnerable to sea level rise. When marshes cannot grow upward due to lack of sediment deposition and fresh-water flux, or when they cannot migrate landward due to artificially protected coastlines, a significant loss of the wetlands may occur. The economically important mangroves may be especially threatened due to their impeded ability to migrate landward. These threats underscore the need for expert management of the coastal zone.

　　The IPCC identified three adaptive strategies at local levels: retreat, accommodation and protection. The retreat response characterizes relinquishing structures in existing developed areas that are threatened by advancing seas. It may entail significant resettlement of local population further inland, beyond the area projected to be affected. The second strategy accommodates the advancing sea, by accepting the fact of future flooding, and by scheduled conversion to alternative economic activities, e.g. switching from agriculture to aquaculture. This response, characteristically, is more inclined to preserve a balance between nature and human needs. The protective response embodies a defensive strategy, where economically prized structures and resources are shielded from the advancing threat. Building sea walls, dams, and locks are common protective strategies.

　　There are numerous examples where mitigation activities, instituted at the eleventh hour, have made less than the full impact that they would have made if they had been attempted earlier. The city of Venice is a celebrated example, where the threat of relative sea-level rise due to accelerated subsidence was finally heeded in the late 1960s and steps were taken to reverse the trend.

　　In the later part of 19^th century subsidence rates in Venice and surroundings had accelerated to 2.6 - 3.7 mm/year because of withdrawal of artesian water in Vince and the surrounding areas. This rate accelerated further in the 20^th century due to rapid depletion of ground water. In the 1950s and 1960s subsidence rates of between 14 and 17 mm/year were measured. The imminent threat to this historical city led to several corrective measures, including building of locks on the inlets to the Venetian Lagoon to control inflow from the open ocean. More importantly, the practice of using artesian water was reserved. A rapid decline in extraction of ground water since the 1970s has slowed the subsidence - parts of the city have actually rebounded by as much as 20 mm. Experience in other areas have shown that total rebound is never much more than about 20 % of the cumulative subsidence. Venice is expected to rebound by a total of only about 30 mm.

　　Mitigation and reversal of adverse consequences of human developmental activities often involve a complete rethinking of long-practiced traditions. A rare example of such a change in policy concerns the northwest coast of the Netherlands. On the Wadden Sea coast past practices had accelerated the subsidence rate to a high 13 mm/year in the last two decades. According to previous practice there would have been an attempt to reclaim the land for agricultural use. Instead, a revised government policy has designated the Wadden Sea area as a sort of "Biosphere Reserve" park, allowing only those activities that avoid conflict with the natural processes. Such forward-thinking policies are imperative if we are to combat the growing threat the combined effects both the global and the local components of advancing seas.