Page 528 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

492 part III The earth–atmosphere interface
Earth’s vast oceanic, atmospheric, and lithospheric profound changes that had transpired in the ocean sys-
tem over the 10 years since the first conference—see www .oceanobs09.net/.
Wind is an important geomorphic agent along coast- lines as well as in other environments. Although wind’s ability to erode, transport, and deposit materials is small compared to that of water and ice, wind processes can move significant quantities of sand and shape land- forms. Wind contributes to soil formation (discussed in Chapter 18), fills the atmosphere with dust that crosses the oceans between continents (discussed in Chapter 3), and spreads living organisms. One study found related mosses, liverworts, and lichens distributed among islands thousands of kilometres apart in the Southern Ocean.
In this chapter: After beginning with a brief look at our global oceans and seas, we discuss the physi- cal and chemical properties of seawater. Next we look at coastal systems, discussing tides, waves, coastal erosion, and depositional landforms such as beaches and barrier islands. A systems framework focusing on inputs (components and driving forces), actions (movements and processes), and outputs (results and consequences) organizes our discussion. We also look at the important organic processes that produce cor- als, salt marshes, and mangroves. Lastly, we examine wind processes—first, wind erosion and the resulting landforms, and then wind deposition, sand dunes, and sand seas.
Global Oceans and Seas
The oceans are one of Earth’s last great scientific fron- tiers. Remote sensing from orbiting spacecraft and sat- ellites, aircraft, surface vessels, and submersibles now provides a wealth of data and a new capability for un- derstanding oceanic systems. Earlier chapters have touched on a number of topics related to oceans. We discussed sea-surface temperatures in Chapter 5 (please review Figure 5.9) and ocean currents, both surface and
deep, in Chapter 6 (Figures 6.18 and 6.20). The location and surface area of the world’s oceans is in Chapter 9 (Figure 9.3).
A sea is generally smaller than an ocean and tends to be associated with a landmass. Figure 16.2 shows the world’s principal seas (a more detailed map of over 60 seas is on the MasteringGeography website). The term sea may also refer to a large inland, salty body of water, such as the Black Sea in Europe. Fisheries and Oceans Canada conducts oceans research (see www.dfo- mpo.gc.ca/science/oceanography-oceanographie/ index-eng.html); in the United States the Na- tional Ocean Service coordinates many scientific activities related to oceans; information is available at oceanservice .noaa.gov.
systems reach a meeting point along seacoasts. At
times, the ocean attacks the coast in a stormy rage of erosive power; at other times, the moist sea breeze, salty mist, and repetitive motion of the water are gentle and calming. The coastlines are areas of dynamic change and beauty.
Commerce and access to sea routes, fishing, and tourism prompt many people to settle near the ocean. In fact, about 40% of Earth’s population lives within 100 km of an ocean coast (Figure 16.1). A 2007 study de- termined that, globally, 634 million people live in low- elevation coastal areas that are less than 30 m above sea level, meaning that 1 in 10 people on Earth live in a zone that is highly vulnerable to tropical storm dam- age, flooding, and rising sea level. Given this population distribution, an understanding of coastal processes and landforms is important for planning and development.
Pollution is also a major concern in coastal areas. According to the United Nations Environment Program (UNEP), about 6 trillion gallons of sewage is discharged into coastal waters each year, along with about 50000 tonnes of toxic organic chemicals and 68000 tonnes of toxic met- als. Aside from the potentially dangerous biological haz- ards it poses, coastal and marine pollution affects coastal tourism, which is a large component of the economy in many coastal cities.
Oceans are intricately linked to life on the planet and act as a buffer for changes in other Earth systems, ab- sorbing excess atmospheric carbon dioxide and thermal energy; yet climatic shifts over the past several decades may now be overwhelming oceanic systems. In 2009, the second Conference on the Ocean Observing System for Climate took place in Venice, Italy, summarizing the
▼Figure 16.1 Bondi Beach, Sydney, Australia. in australia, over 85% of the population lives within 50 km of a coast. The country as a whole has over 36 000 km of coastline and over 10 000 beaches. Pictured here are surfers and beachgoers at one of Sydney’s most popular beaches. [Patrick Ward/Corbis.]