Briny future for vulnerable Malta

Later this week, scientists on the Intergovernmental Panel on Climate Change will report on how global warming will impact the world now and in the future.

Rising sea levels could cause increased flooding throughout the world, affecting the lives of millions of people.

BBC World Service environment reporter Matt McGrath has been to Malta to see how rising waters could make life more difficult on the Mediterranean island in future.

About 400,000 people live on the tiny island of Malta. It is one of the most crowded spaces in the world.

It is also highly vulnerable to climate change. Rising sea levels in the Mediterranean over the next century caused by global warming threaten to submerge parts of the island.

But there is another aspect to sea level rise that is already having a significant effect on Malta. It is the impact on the supply of drinking water.

In the tourist season Malta's population trebles. All these extra people put great pressure on the island's water supply, which depends on a vast reservoir that lies under the island.

Because the fresh water is less dense than salt water, this reserve effectively floats on the sea.

Down the centuries, the Maltese have developed a clever system of underground tunnels, called galleries, to extract the water for human consumption.

Because the rising sea is poisoning their ground water with salt, the authorities in Malta are investing in desalination to make the sea water drinkable. More than half the potable water on the island is now produced in this way.

But desalination plants contribute significantly to global warming as they are powered by fossil fuels. As a member of the European Union, the Maltese are already facing sanctions for failing to co-operate on carbon cutbacks with Brussels.