it comprises only about 8 percent of Earth’s surface, this area supports more than 25 percent of total global primary production and yields nearly 90 percent of present world fisheries production (Ryther, 1969; Sherman, 1994). Oceanrelated activities and industries provided over 2.3 million jobs in 2004.2 About 35 percent of the world’s population currently lives within 100 km of a shoreline (Nicholls and Small, 2002); this number is projected to grow to 75 percent in a few decades (Vitousek et al., 1997). Over two-thirds of the world’s largest cities, with populations greater than 1.6 million, are located in coastal areas. These are often in the vicinity of estuaries or coastal wetlands, accounting for more than 50 percent of wetland loss (Walker, 1990; Anderson and Magleby, 1997). Coastal governance issues (e.g., coordination and support of ocean and coastal management; coastal and marine spatial planning3) are currently at the forefront of both public attention and national priorities (CEQ, 2010); and this is not expected to decrease by 2030.

The polar regions will almost certainly also be of profound importance in the next 20 years, as noted by inclusion in the National Ocean Policy (NOP) objectives (CEQ, 2010; E.O.13547). Although they do not have significant populations in numbers, they are presently subjected to rapid environmental changes (e.g., warming, sea ice reduction, changes in freshwater fluxes) that may have great impacts for commercial activity, including resource extraction and transportation. These also require special considerations when discussing ocean infrastructure needs. The following 13 questions were chosen to encompass a broad range of issues regarding environmental stewardship from the poles to the equator.

How Will Sea Level Change on a Range of Spatial and Temporal Scales and What Are the Potential Impacts?

The trapping of heat by anthropogenic greenhouse gases is likely to lead to sea level rise on a wide range of spatial and temporal scales (NRC, 2010b). As so many people live and work near sea level, sea level study and prediction will continue to be a topic of active research in the coming decades. In 2007, the Intergovernmental Panel on Climate Change (IPCC) estimated sea level rises between 0.18 and 0.6 m by 2100 (IPCC, 2007). More recent estimates that take into account ice melt on Greenland and western Antarctica increase these estimates to between 0.8 and 2.0 m (Pfeffer et al., 2008). Increased heat in the ocean-atmosphere system causes sea level rise in two ways: (1) a warmer ocean is less dense, and thus has more volume even if its mass remains constant; (2) melting of ice on land adds mass to the ocean, raising sea level (Nicholls and Cazenave, 2010). Even if these fundamental effects were perfectly understood and predicted, there would still be issues related to regional sea level rise that depend strongly on local conditions (Milne et al., 2009), including subsidence, tides, and storm activity. Tides and storms contribute to local inundation, so the most damaging effects of a higher sea level will likely be felt more frequently. Seasonal effects could be significant, as runoff contributes to flooding in areas of high precipitation. For low-lying coastal communities, sea level rise will be a threat to societal infrastructure (e.g., streets, buildings, sewage, drinking water supplies, gas, electricity [Nicholls and Cazenave, 2010]). Ports and naval facilities, in particular, will need to address the impact of sea level rise and changing dynamics of coastal erosion and sedimentation in order to maintain effective operations. Also of concern are more than 200 existing marine laboratories that currently provide support for a wide range of ocean research and education activities (Sebens, 2009), which will have to adapt to coastline changes as a result of rising sea level. On regional and global scales, ocean temperature and therefore sea level will continue to change in response to natural, interannual modes of climate variability such as the El Niño-Southern Oscillation (ENSO), and many of these changes will be irreversible over both short and long time scales (Solomon et al., 2009).

How Will Climate Change Influence Cycles of Primary Production?

Major changes have and will continue to take place in the world’s ocean (e.g., changes in temperature, stratification, circulation, oxygen distributions, trace metals inputs, and pH) (e.g., Sarmiento et al., 2004; Doney et al., 2009; Reid et al., 2009; Keeling et al., 2010; Steinacher et al., 2010). These changes all have direct and indirect impacts on ecosystem processes, including limitation of primary production by nutrients, shifts in the major phytoplankton groups that dominate open ocean waters, and changes in zooplankton behavior and distributions (Reid et al., 2009). Global trends in primary productivity have been linked to changes in surface temperature and mixed layer dynamics (Behrenfeld et al., 2006; Martinez et al., 2009; Chavez et al., 2011). While some of the basin-scale trends are correlated with natural oscillatory cycles (e.g., the North Atlantic Oscillation, Pacific Decadal Oscillation), the exact mechanisms that force changes in ecosystem productivity are still uncertain (Martinez et al., 2009). Indeed, a recent study concludes that long (~40 years) records of persistent, high-quality, global-scale data are needed to separate decadal oscillations from climate effects on ocean productivity (Henson et al., 2009; Chavez et al., 2011).

Modulation of the surface ocean ecosystem’s composition, stock, and productivity influences the biological pump that functions to transport atmospheric carbon dioxide (CO2) incorporated into organic carbon into the deep ocean

2

http://www.oceaneconomics.org.

3

According to the Final Recommendations of the Interagency Ocean Policy Task Force (CEQ, 2010), U.S. coastal and marine spatial planning “is a comprehensive, adaptive, integrated, ecosystem-based, and transparent spatial planning process, based on sound science, for analyzing current and anticipated uses of ocean, coastal, and Great Lakes areas.”



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