The nature and magnitude of the human activities

Communications and transport

The network of shipping routes covers the whole ocean. There are particular choke points, where large numbers of ships pass through relatively limited areas, with consequent increases in the risks of both disasters and chronic pollution problems. The impending opening of the Panama Canal to larger ships will tend to modify the pattern of ship movements. Global warming is likely to lead to more use of the routes between the Atlantic and Pacific Oceans through Arctic waters, with increased risks to ecosystems that have slow recovery times, and where infrastructure for response to disasters does not currently exist. Shipping traffic grows in relation to world trade, and considerable further growth is therefore likely. Cargo ships have been steadily increasing in size, but limits are probably being reached because of the draught limitations of some of the world's choke points. More emphasis is being placed in many areas on coastwise movement of goods by ship to reduce pressures on roads. Passenger shipping is largely divided into cruise ships and ferries. The cruise-ship market is growing steadily and is also moving to larger vessels. Ferries are most important around the Baltic Sea, the North Sea and the Mediterranean Sea (where there are large international cargo movements over relatively short crossings) and in States with a large scatter of islands (such as Greece, Indonesia and the Philippines).

Ports form the nodes of the network of shipping routes. General cargo ports have changed completely over the past 50 years with the introduction of containerization. A hierarchy of these ports is developing, with transhipment as cargoes are cascaded to the ports nearest to their final destinations. Specialized oil and gas ports are naturally located near the sources of supply and the major centres of demand. This pattern is likely to change as a result of changes in the oil and gas markets. Other bulk terminals respond to the same drivers. In some cases, there are challenges because of the location of sources of supply or established delivery centres near important sites for marine ecosystems and biodiversity.

Submarine cables likewise cross nearly all ocean basins. The development of fibre-optic cables in the 1980s permitted the parallel development of the internet.