why must oil be moved around the world by ocean tankers?
The answer lies in the fact that oil is (mainly) consumed in different
localities than it is produced, globally speaking. This was not always
the case for countries such as the US, which used to produce enough
oil to supply demand in the contiguous 48 states. Most of the countries
that began mining oil early-on also developed a large dependence on
oil to "fuel" their economies; as they used up their own supplies,
they looked elsewhere around the world. It is no suprise that the major
global oil companies are today mostly run by US and western European
corporations, since these are the countires that first began large-scale
petroleum use. It is also no suprise that more oil is consumed by
western nations than by the major producer nations in the Mideast,
South America and Asia (it is worth pointing out however that the
US is still considered a "major" oil producing nation as well).
So, for the reasons given above, oil must be transported between its points of production and its points of use. Why is much of it transported by ship? Well, this is simply the most efficient way to move large quantities of oil across the oceans. Keep in mind however that large quantities of oil are also moved over land by pipelines (for instance, the Alaska pipeline and similiar pipelines in parts of the Mideast and former Soviet Union).
The problems associated with each mode of transport have been largely overcome by advances in engineering. However, accidents (e.g., Exxon Valdez) still happen. In the end, these accidents (and the associated environmental impacts) will never cease until we begin using other sources of energy to "fuel" our lifestyles.
Dr. Ken Rubin, Assistant Professor
Department of Geology and Geophysics
University of Hawaii, Honolulu, HI 96822