Mangrove forests are growing back, new study says

The world's mangrove forests, which protect millions of people from storms - and soak up vast amounts of planet-warming gases - are staging an unexpected comeback, scientists have found.

For decades these swampy trees had been declining as they were cleared for fish farms and housing.

However, since 2010, the world has been gaining more mangroves than it has been losing, in a win for climate change, according to a new study.

Mangrove forests are made up of thick trees that have adapted to live in saltwater.

They usually grow in mud along coastlines in tropical climates, and have a network of roots that stick out of the water.

Their growth is really important for combatting climate change, because they can store up to five times more carbon dioxide than land forests.

The study also found that many existing mangrove forests were actually becoming healthier.

The lead author of the study, Dr Zhen Zhang from Tulane University in the US, said: "We are moving in the right direction because you can see a very clear trend of decreased loss rate."

Scientists think this is driven by stronger legal protections and more people understanding the importance of mangroves.

"So, I think we are going the right way," said Dr Zhen.

Mangroves have been under threat from human activity.

The rise of fish farming and the expansion of coastal cities has meant many have been chopped down.

From the 1980s to 2010, more than 12,000 sq km (4,600 sq miles) of mangroves were cleared or destroyed across Asia, Africa and South and central America.

That is equivalent to an area the about the size of Jamaica.

Since the 1980s, that area has reduced to around 849 sq km (328 sq miles).

Mangroves are one of the world's unsung environmental heroes.

Mangrove forests are found in the tropical regions of 123 countries.

Not only do they store up to five times more, external carbon dioxide than land-based forests, but their tangled roots can also slow down waves and protect coastal communities from storm surges and tsunamis.

These same roots provide a perfect nursery for many species of fish and other marine life - protecting them from predators and providing ample food.

They support an estimated 2.4 billion people living along the coast by providing timber, medicine and coastal protection.

These benefits, though, have come under serious threat over the past century as the rise of fish farming, agriculture and the expansion of coastal cities and towns have seen mangroves chopped down and rapidly removed.