Sea Technology

JAN 2018

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www.sea-technology.com January 2018 | ST 41 quences of climate change, the ocean's rapid and drastic transformation will likely have a disproportionate impact on the global population. Scientists are still assessing the full scope of how acid- ification interacts with the ocean's complex systems, but the latest findings indicate the impacts are already be- ing felt today and could become even more severe. The oceans currently absorb roughly a quarter of the carbon dioxide (CO 2 ) humans produce annually. According to the World Meteorological Organization, human activi- ty has pushed atmospheric CO 2 concentrations to their highest levels in 800,000 years, fueling unprecedented changes in ecological systems. This excess of CO 2 has led to the oceans absorbing 560 billion tons of CO 2 over the past 250 years, making surface waters 30 percent more acidic during that span. Alarmingly, the current rate of change in ocean acidity is around 50 times faster than any known historical rate. Projections of atmospheric and oceanic CO 2 concentrations indicate that by centu- ry's end, the average surface ocean pH could reach levels not seen in more than 50 million years. In addition to their rising acidity, ocean waters have also been growing warmer. Although the oceans are able to absorb massive amounts of heat, this process has been kicked into overdrive by anthropogenic climate change, as evidenced by an increase in global ocean surface tem- peratures during the past 30 years. Scientists estimate that since 1955, more than 90 percent of the excess heat re- tained by Earth due to atmospheric greenhouse gases has been absorbed by the oceans. Warmer ocean tempera- tures can alter ocean circulation patterns, which could subsequently shift the availability of nutrients, the struc- ture of existing food webs and the location of preferred habitat temperatures for marine fish and invertebrates. As various fish species migrate to more favorable waters, resource-poor fishers and subsistence-dependent, immo- bile communities will be in danger of getting left behind. An increase in seawater acidity has made it more dif- ficult for organisms with calcium carbonate shells and skeletal components to form and maintain those essen- tial structures. Many marine calcifying animals, includ- ing shellfish, zooplankton, coral and pteropods, are cru- cial parts of the marine food web. For instance, a drop in the availability of foundational food sources, like ptero- pods and other small marine organisms, could result in igate busy waterways. In a 2015 precision navigation project, NOAA partnered with the Ports of Los Angeles and Long Beach to generate comprehensive data on under-keel clearance using a network of observational buoys. When navigating large 1,100-ft. vessels, a pitch of 1° causes the vessel to dip 9.6 ft.—a massive movement in channels with only 11 ft. of under-keel clearance. Pri- or to precision navigation, cargo had to be removed from these vessels offshore to increase under-keel clearance in waterways. Now, port operators can navigate massive ships into docks without removing cargo at sea, a change that could reduce costs by millions of dollars and en- courage increased international business. Recent appropriations have helped to sustain current systems and expand some elements. However, to achieve necessary growth, additional funds and programs will be needed, including those that capitalize on public-private partnerships. Broadening the definition of marine trans- portation infrastructure to include information infrastruc- ture will help to generate new funding streams. With this definition, shipping and freight communities can en- courage consistent funding through ongoing dialogs with congressional leaders, private sector financiers, and state and regional interests. The competitiveness of U.S. industries depends on strong American ports and a thriving shipping industry. Advancements in our ability to monitor, understand and disseminate information about ocean conditions are cru- cial to safe and efficient maritime commerce. Providing specific funding support for information infrastructure is critical for MTS function and U.S. economic security. In- cluding marine transportation in federal initiatives will advance U.S. leadership in technology, leverage proven public-private partnerships and incentivize state, local and private sector investments. ST Review&Forecast Ocean Acidification, Warming Waters Endanger Global Fisheries By Brian La Shier Policy Associate Environmental and Energy Study Institute D iscussions about climate change typically center on the effect of greenhouse gases on the atmosphere, but those emissions have a larger footprint than many realize. Ocean acidification, primar- ily the result of atmospheric carbon being absorbed by the ocean and altering sea- water pH levels, poses a severe threat to aquatic eco- systems. Despite acidification's relatively low profile in the public eye, it poses a grave risk to the world's fish- eries and the billions of people who rely upon them for income and sustenance. Similar to the terrestrial conse- "For every 1° C increase in ocean temperature, the number of cholera outbreaks in humans rose by 200 percent due to the presence of Vibrio cholera bacteria in shellfish."

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