The benefits and downsides of building into the sea

As urban areas get more crowded, building new land and even floating homes is becoming more economic - but is it storing up future problems?

All around the world, cities are edging further into the sea. Plans are afoot to build huge islands and giant constructions in coastal areas, featuring the dredging and dumping of million of tonnes of material.

What are the implications for ocean life and ecosystems as we build more and more into the ocean?

This is one of the questions that will be discussed at the BBC Future's World-Changing Ideas Summit in Sydney in November.

IN WHAT WAYS ARE WE BUILDING INTO THE SEA?

Cities have been creeping further into the ocean ever since we first starting building harbours.

Land reclamation is big business and today, numerous countries are 'taking back' land from the sea to expand their coastlines and territory.

Almost every coastal province in China has projects underway to build out the coastline, either by dumping soil from the mainland, dredging it up from further out to sea, or by blocking river estuaries and allowing the silt to build up.

The island-state of Singapore has added 22 per cent onto its size over the past 50 years by building out into the surrounding waters using sand, earth and rock quarried and purchased from elsewhere.

Their fervour for reclamation is such that they are the world's largest importer of sand.

But it is Dubai that is home to perhaps the most famous of reclaimed areas.

Its visually spectacular and entirely artificial Palm Jumeirah archipelago, home to the obscenely wealthy, is built from an estimated 110 million cubic metres of dredged sand.

And as one of the most densely populated nations on Earth, the low-lying Netherlands has long been driven to reclaim large swatches of its coastal swamps and marshes to house its ever-growing population.

SOUNDS AMBITIOUS. SURELY THERE ARE DOWNSIDES?

For ocean ecosystems, certainly.

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