1998 Year of the Ocean Impacts of Global Climate Change 



EXECUTIVE SUMMARY 



The Earth's weather and chmate are the resuU of the redistribution of heat. The major 

 source of heat to the surface of the Earth is the sun, principally through incoming visible 

 radiation most of which is absorbed by the Earth's surface. This radiation is redistributed by the 

 ocean and the atmosphere with the excess radiated back into space as longer wavelength, infrared 

 radiation. Clouds and other gases, primarily water vapor and carbon dioxide, absorb the infrared 

 radiation emitted by the Earth's surface and remit their own heat at much lower temperatures. 

 This "traps" the Earth's radiation and makes the Earth much warmer than it would be otherwise. 



Most of the incoming solar radiation is received in tropical regions while very little is 

 received in polar regions especially during winter months. Over time, energy absorbed near the 

 equator spreads to the colder regions of the globe, carried by winds in the atmosphere and by 

 currents in the ocean. Compared to the atmosphere, the ocean is much denser and has a much 

 greater ability to store heat. The ocean also moves much more slowly than the atmosphere. Thus, 

 the ocean and the atmosphere interact on different time scales. The ocean moderates seasonal and 

 longer variations by storing and transporting, via ocean currents, large amounts of heat around 

 the globe, eventually resulting in changing weather patterns. 



The ocean also plays an important role in climate change. Long-term impacts of climate 

 change in coastal areas, such as sea level rise or storm surges, could result in the increased 

 erosion of shores and associated habitat, increased salinity of estuaries and freshwater aquifers, 

 altered tidal ranges in rivers and bays, changes in sediment and nutrient transport, and increased 

 coastal flooding. Such changes have considerable implications for U.S. coastal areas where the 

 majority of the country's population and significant economic activity is concentrated. 



The purpose of this document is to consider how the ocean influences weather and 

 climate and how climatic changes could impact valuable coastal areas. It also addresses the 

 barriers to progress and the opportunities presented by the 1998 Year of the Ocean to better 

 understand and predict weather and climate variability and to address the coastal impacts of 

 global climate change. This topic spans such a broad array of considerations that it will be split 

 into three parts: seasonal to interannual climate impacts, decadal to centennial climate impacts, 

 and coastal global climate change impacts. Options for consideration to further advance efforts in 

 each topical area are included. 



Seasonal to Interannual Climate Impacts 



The global atmosphere and world ocean are an interactive system. The most important 

 air-sea interaction signal comes from the El Nino/Southern Oscillation (ENSO) which originates 

 in the tropical Pacific. In a warm episode (El Nino), the pool of warm water that is normally 

 found in the western Pacific expands eastward, carrying with it portions of the precipitation 

 normally found in the far western Pacific. This shift in the distribution of tropical convection 

 leads to shifts in jet stream tracks, resulting in climatic anomalies around the world. The ENSO 



G-2 



