Source: Shipping density data adapted from National Center for Ecological
Analysis and Synthesis, A Global Map of Human Impacts to Marine Ecosystems.
(Detailed PDF Map)
Domains of Maritime Circulation
Oceanic masses and rivers are the two major components of maritime
circulation. Oceanic masses account for 71% of the terrestrial surface.
The four major oceans relevant to maritime circulation are: the Pacific
(165 millions square km), the Atlantic (82 million square km), Indian
(73 million square km) and the Mediterranean (2.5 million square km).
Although the Pacific is by far the largest ocean, it is not the most
significant as far as maritime circulation is concerned. It supports
about 25% of the global maritime trade (this share is growing
rapidly) and only a small portion of it
is used for commercial transportation purposes. The northernmost parts
of the Atlantic as well as the southernmost parts of the Atlantic, Indian
and Pacific oceans are not much used mainly because of hazardous
(mainly ice) and their remoteness to the centers of economic activity.
The shipping density is derived from the paths of mobile data
points of a sample of commercial vessels (about 11% of the world
fleet) counted over a year on a grid of 1 square kilometer cells. It
is not weighted by ship size and is not necessarily fully
representative of all commercial activity. Even if maritime transportation has experienced remarkable improvements
in its safety and reliability, maritime routes are still hindered by
dominant winds, currents and general weather patterns. The North Atlantic
and the North Pacific (50 to 60 degrees north) are subject to heavy
wave activity during the winter that sometimes impairs navigation, and
may cause ships to follow routes at lower latitudes, thereby increasing
route lengths. During the summer monsoon season (April to October),
navigation may become more hazardous on the Indian Ocean and the South
About 50 countries have an inland navigation network of more than
1,000 kilometers. Rivers may not be useful for commercial navigation if their orientation
does not correspond to the directions of transport demand. Thus, many
of the major rivers of Russia flow north-south, while the main trade
and passenger flows are east-west. Shallow draught and extensive obstacles,
such as rapids, may also limit navigation. However, many rivers, such
as the Rhine or the Chang Jiang, are significant arteries for water
transport because they provide access from the oceans to inland markets.
Geographically, maritime activities can be divided in two major categories:
- Interior (Fluvial) Waterways. Fluvial transportation is well suited
to transport bulk cargo, has low costs and is the most environmentally
friendly. It plays an important role for several industrial countries
with large waterway systems such as the Volga, the St. Lawrence
/ Great Lakes, the Mississippi, and the Rhine. All these
networks have a tree-like structure which has been broken by the
construction of canals linking different tributaries. Domains of inland
navigation in North America, Europe and China are not equivalent
in terms of size of ships implying different operational characteristics.
Most waterways are solely justified by bulk cargo requirements.
However, accelerated integration of industrial and market regions to maritime
shipping because of container barge services can be noted, especially
in Western Europe. A growth and diversification of activities on the Chinese
waterways has also been a dominant trend as China integrated the
global economy and as the growth of its domestic economy resulted
in a growth of freight shipped on its fluvial network.
- Transcontinental Waterways. Seaborne trade has experienced
very strong growth, especially over the Pacific. This is notably
linked to the dependence of developed countries for energy, minerals
and agricultural products. There is an increased importance of large
maritime companies as well as a division of labor and capital in
the maritime industry. Markets, technology and capital are provided
by developed countries and labor by developing countries.