x Abu Dhabi, UAETuesday 25 July 2017

Abu Dhabi plants 250,000 saplings to save mangroves

University scientist warns the ecosystems will have few places to retreat to when climate change causes rises in sea levels.

A dredger near the capital's coastline moves sand from an area near mangroves.
A dredger near the capital's coastline moves sand from an area near mangroves.

ABU DHABI // The Environment Agency-Abu Dhabi has planted 250,000 saplings in an attempt to offset the threat posed to kilometres of lush mangroves by development along the capital's coast. "You cannot stop development, but you can do it so that development is sustainable," said Dr Thabit Zahran al Abdessalaam, the agency's director of biodiversity sector.

"It is not that we have not made mistakes. We have, but we are trying to correct them," he said. "Each and every project has to go through a process of environmental impact assessment. We have stopped some, not many, but some projects." Tomorrow, M, this newspaper's magazine, takes a sweeping look at Avicennia Marina - the black or grey mangrove - the only species that grows in the UAE and one that is threatened by development and climate change.

There are about 50 species of mangroves in the world and they thrive in conditions that would kill other plants - tides, salty water and soils poor in oxygen. Also known as the sea forests of Arabia, mangroves are salt-tolerant trees that grow naturally in low-lying mudflats along the coast. With 31 square kilometres, Abu Dhabi is home to the vast majority of the country's mangrove swamps, and accounts for almost a quarter of all mangroves in the Gulf.

Among avicennia marina's adaptations are aerial roots that stick out from the mud, which allow it to breathe, and pores along its leaves through which it secretes salt. Development - such as the dredging that can be seen from Al Salam Street - is not the only worry. The mangroves are also vulnerable to climate change, say a team of scientists from UAE University, as different scenarios about rising sea levels suggest they could destroy from five to 80 per cent of the ecosystems.

"In the last 11 years, we had an 11 centimetre increase in the level of the Gulf," said Dr Tarek Youssef, the associate professor at UAE University who leads the team behind the first locally produced report on the mangroves' vulnerability. Quite how water levels will change in future depends on a multitude of factors, some of which scientists are just beginning to understand, so the extent of the threat is as yet unknown.

The International Panel on Climate Change (IPCC), the world's pre-eminent scientific authority on the issue, predicted in 2007 that a rise in sea levels of 18 to 59 centimetres was expected by 2100. "This is the least [worrying] scenario," said Dr Youssef, whose study was funded by the Emirates Foundation. If that happens "we will lose five per cent of the mangrove area in Abu Dhabi". Unfortunately, at the time the IPCC calculation was made, scientists did not account fully for the melting of the polar ice sheets. They now believe the process is occurring more quickly than previously thought.

This means an even greater increase in sea levels, with some researchers now suggesting a rise of more than a metre by 2100. Using digital models of Abu Dhabi, Dr Youssef and his team investigated the effects of various levels of projected flooding. They found that if sea levels rose by 1.5 metres, 45 per cent of mangroves would be lost. A rise of two metres would cause the loss of 65 per cent, while a three-metre rise would cause 80 per cent to disappear.

When it comes to climate change and mangroves, development proves an aggravating factor. Scientists hope that some mangroves would be able to migrate inland as sea levels rise. In this scenario, as trees on the frontline die, they would create a fresh layer in which new saplings could grow. However, with the development of walkways, roads and resorts along waterfronts, mangroves would have nowhere to retreat to, said Dr Youssef. "If we prevent this natural regression, we are doing the wrong thing. There is no room for migration."

The team's final report is expected by the end of the year. vtodorova@thenational.ae