A new European report says the warming oceans caused by climate change are leading to the spread of dangerous bacteria in the sea.

The report to be presented Wednesday at a two-day global warming conference in Brussels predicts that millions of people may be exposed to contaminated food and water. They also could become sick by swimming and sailing in the dirty seas.

The study by 17 European marine institutes says the warming is leading to a proliferation of the Vibrio bacteria, which has been linked to such diseases as cholera and gastroenteritis.

The report also says the Earth's oceans are heating up at a rate faster than previously thought, causing ice sheets to melt and putting some island nations and coastal regions in peril.

Many scientists believe human activity, such as pollution from cars and factories, is contributing to global warming. They are demanding rich and developing countries take immediate action to cut emissions.

Others call climate change a natural phenomenon and say there is still no proof humans are a major contributor. They argue that taking drastic action could hurt global economies.