In tonnage terms, the amount of oil transported by sea increased from 1,600 million tonnes in 1992 to over 2,400 million tonnes in 2008. Over 34,000 million tonnes was carried over the 16 year period. By contrast, the number of major oil spills during the same period shows a steady reduction. Although serious accidents occasionally occur - the loss of the 'Erika' and 'Prestige' being recent high profile examples - the trend shows a continuing improvement, both in quantity and frequency of oil spills each year.

Between 1992 and 2008, world seaborne trade rose from 17,541 billion tonne miles to an estimated 32,746 billion tonne miles, an increase of around 85%. The carriage of oil and petroleum products accounts for a significant part of this increase, rising by about 40% from 8,043 billion tonne miles to an estimated 11,292 billion tonne miles during the same period.

The Changing Landscape of Global Poverty 2005 to 2015. 

There are several causes of ocean pollution including oil pollution, marine debris, toxic materials, and ocean dumping and mining. Oil pollution is not only caused by large devastating tanker spills, it is also caused through runoff from land and industrial wastes which find their way to the ocean through drains. Other causes include intensive farming, septic tank, pesticide, animal dung, household waste, water table, waste water, nuclear waste...