By 2050 it is estimated that the world's population could have increased to around 9 billion. Of these, some 60 percent will live within 60km of the sea. The agricultural and industrial activities required to support this population will increase the already significant pressures on coastal areas.
For more on marine pollution, visit Wikipedia Marine Pollution.
Major oil spills from tankers are the most obvious form of oil pollution in the oceans, these spills, however, account for only 10-15 per cent of all the oil that enters the ocean every year.In addition to the major visible short term impacts of an oil spill, severe long term problems can also result. In the case of the Exxon Valdez which ran aground in Alaska in 1989, biological impacts from the oil spill were still present 15 years after the event.
The oils spills can be toxic to many organisms and can smother other organisms. The layer of oil on the surface of the water prevents oxygen from entering the water. For seabirds, the most common cause of death is from drowning, starvation and loss of body heat following fouling of feathers by oil.
Used engine oil can end up in waterways. Much oil in runoff from land and municipal and industrial wastes ends up in the oceans. Every year oily road runoff from a city of 5 million could contain as much oil as one large tanker spill. Every year, bilge cleaning and other ship operations release millions of gallons of oil into navigable waters, in thousands of discharges of just a few litres each.
Air pollution, mainly from cars and industry, places hundreds of tonnes of hydrocarbons into the oceans each year. Particles settle, and rain washes hydrocarbons from the air into the oceans.
Some ocean oil "pollution" is natural. Seepage from the ocean bottom and eroding sedimentary rocks releases oil.
For more on environmental impact of oil spills, visit here.
For more on other sources of oil pollution, visit here.