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[edit] First Global Alert on Oceans

Scientists have sounded a worldwide alert on the adverse effects of human actions on the world’s oceans which has left only 4% of the seas pristine. In the first ever portrait of dispersed human impacts on the oceans , scientists have revealed a mix of as many as 17 different kinds of worldwide resource depletion and ecosystem degradation, by accident and intent, which are broadly termed as organic pollution. This includes agricultural runoff and sewage; damage from bottom-scraping trawls; and intensive and traditional fishing along coral reefs.

As a result about 40% of the ocean areas are strongly affected and just 4% (Polar seas) are still pristine, but poised to change. Some familiar human impacts are damages to coral reefs and mangrove forests through direct actions like constructions or subtler ones like loss of certain fish which shape the ecosystems. The densely populated coasts have been heavily affected by continental shelves and slopes as well.

A slow drop in the pH of surface waters around the globe is believed to be the most significant and widespread human impact. The billions of tons of carbon dioxide added to the atmosphere from fuel and forest burning each year, is absorbed in water where it forms carbonic acid, leading to high levels of oceanic acidification.

Hence this progressive shift in ocean chemistry could eventually disrupt shell-forming plankton and reef-building species.