Loss of mangroves
The Indian city of Mumbai is losing more mangrove forests every day, as developers cut them down to build blocks of flats, office towers and now an airport.
Mangrove forests are not the first thing most of us envision when we think about protecting the environment. But in Mumbai they save lives - literally.
In July 2005, the city came to a standstill due to massive flooding. About 1,000 people died while tens of thousands were stranded by the floods.
Scientists say that if Mumbai had protected its mangroves, fewer people would have died and less property would have been damaged by the floods.
Mangroves grow along seashores and saltwater swamps in the tropics. The term mangrove is used to describe a wide range of plants and trees.
About 40 per cent of Mumbai's mangroves were cut down between 1995 and 2005. A few patches are still left in the heart of the city, hinting at the luxuriant forests that once covered the whole area.
Mangroves play an important role in protecting Mumbai's shoreline by creating a buffer zone between the sea and the land.
Mangroves are hard to visit because the ground is muddy and often tangled with plants and roots. Many people think that such swampy land is a waste of space, and therefore should be used for building on.
But mangroves help the land to absorb rainwater. When they are gone, the water runs off the land and into the sea much faster, causing flash floods and erosion.
Yet Mumbai continues to cut down mangroves. Plans for a second city airport threaten even more of their habitat.
Hong Kong also has mangroves, and they are under threat from developers, who want to build flats and shopping malls on the sites.
You can see mangroves in the Wetland Park in Tin Shui Wai, New Territories, and learn more about how they protect our coastlines.
Cameron is available to speak to students about environmental and climate change issues as well as his recent Arctic sailing expedition. Contact info@openpassage expedition.com