Land/Sea Interface 



This is the newest program of Global Geosciences and is a cross-directorate effort involving the 

 Division of Biotic Systems and Resources of the Biological, Behavioral and Social Sciences 

 Directorate (BBS) and the Biological and Chemical Oceanography Programs of the Division of 

 Ocean Sciences. It is part of Global Ecosystem Dynamics within Global Geosciences. 



Interfaces between land and ocean are only a small part of the earth's surface, but they are of 

 great global importance in terms of biological productivity, geochemical processes, origin of 

 sedimentary rocks, and the evolution of life. Human activities have already wrought significant 

 changes upon the interconnections of land, freshwater, and the coastal ocean. Furthermore, these 

 couplings are highly sensitive to changes in global climate. 



As a result of land- and water-use practices, flow volumes of many of the world's rivers have 

 been significantly altered. Their content of dissolved and particulate substances has changed, 

 resulting in two- to fivefold Increases in river nutrient levels In developed regions during the 

 latter half of this century. Such changes are also likely to be occurring in developing countries 

 as a result of deforestation, population growth, and wider use of fertilizers. 



Present day coastal environments are the product of relatively stable sea level conditions over 

 the last 7,000 years. The widely-predicted atmospheric warming could cause a rapid rise in 

 eustatic sea level at a rate of perhaps more than one centimeter per year in about fifty years. 

 Significant melting of polar ice could raise sea level several meters more in the next century. 

 Global climatic changes may dramatically alter regional temperature regimes and precipitation 

 (and, consequently, runoff) patterns. These changes may,in turn, influence terrestrial, 

 freshwater, and coastal marine ecosystems and their biota. 



Some major questions to be addressed are: 



• How do modifications in the flux of materials from land to rivers and from rivers, 



wetlands, and estuaries to the coastal ocean, caused by complex interactions of global and 

 local human activities, affect aquatic and marine ecosystems and global biogeochemical 

 processes? 



• Do these changes have significant implications for the global carbon budget? 



• What will be the effects of global climate changes, including changes in temperature, 



precipitation, and sea level rise, on aquatic and coastal ecosystems and on the large 

 human populations that live In these environments? 



The major elements of this initiative are: 



• Utilization of the new generation of satellite sensors to provide visualizations and promote 



computer modeling of these environments as integrated systems; 



• Integrated studies of fluxes of materials within watersheds and receiving estuaries and the 



biological responses to variation in these fluxes; 



18 



