By Janet Ranganathan, Sarah Parsons and Jasmine Qin
More than 200 small islands rise from the jade waters of the Bay of Bengal. Gnarled roots, shrubs and trees stretch across thousands of miles of land and sea. Villagers paddle along waterways in search of crabs and fish. Bengal tigers lurk within dense forests, emerging to swim the narrow channels.
Welcome to the Sundarbans, a swampy stretch of low-lying islands and coastal forest spanning from the eastern edge of India to southwestern Bangladesh. More than 13 million people call the area home, making their living fishing, shrimping, farming and gathering honey. The region also supports more than 300 types of plants and nearly 700 species of wildlife, including threatened Indian pythons, estuarine crocodiles and Ganges river dolphins.
Sundarbans means “beautiful forest” in Bengali, and the area is true to its name. It’s home to the world’s largest contiguous stretch of mangroves, trees and wetlands that survive in brackish water. Mangroves provide timber and food, prevent soil erosion, support marine life, and buffer India’s and Bangladesh’s coasts against storms and tidal waves.
Mangroves, highlighted in green above, stretch from eastern India to southwestern Bangladesh.
But the mangroves are also increasingly threatened. Pressures like population growth and sea level rise are pushing in on the Sundarbans’ forests from all sides.
We used Resource Watch to explore threats to mangroves and the people who rely on them. Here’s a visual look:
A Changing Landscape
The landscape is already changing rapidly in this area of the world. Some parts are getting drier — mainly to the northeast and west of the mangroves — while others are getting wetter, especially directly north of the mangroves.
The map above shows increases and decreases in surface water occurrence from 1984 to 2015. In the mangroves and four districts surrounding them (covering 4.8 million hectares), 47 percent of the area got drier and 38 percent got wetter.
Flooding and Rising Seas
Seas are rising twice as fast in the Sundarbans as the global average. A 2013 study from the Zoological Society of London found that the area is losing up to 200 meters of coastline a year. Salt water regularly engulfs rice paddies and fish ponds. Floods wash away villagers’ thatched-roof huts and destroy their belongings. Many people have fled to nearby cities — those who stay live in fear of when the waters will come for them.
The situation is poised to worsen. Scientists predict oceans to rise up to 2 meters by 2100 due to climate change. In the mangroves and neighboring districts, this amount of sea level rise would inundate 320,000 hectares (791,000 acres), an area of land three times the size of Hong Kong. A 1.5-meter rise in seas would flood 208,000 hectares (514,000 acres).
Two meters of sea level rise would inundate 320,000 hectares of land in the mangroves and areas surrounding them.
Mangroves would typically adapt by retreating further inland to escape the rising seas. This isn’t an option in the Sundarbans, though, because threats also loom to the north.
The population in the Sundarbans region has exploded over the past 40 years. The slider below shows population change from 1975 to 2015. You can see people spreading out from Kolkata, India, a major city, to the surrounding areas. This population growth is pushing right up against the mangroves, hampering their ability to retreat inland and continue protecting people and infrastructure from the growing effects of climate change.
As the population and resulting infrastructure development move further toward the coasts and salt water pushes further inland, mangroves are becoming impossibly squeezed.
A Critical Moment to Act
There is a silver lining here: While deforestation is rising in many forests throughout the world, the Sundarbans’ mangroves have been remarkably well-preserved. Much of the mangroves have been designated as protected areas and nature reserves. WRI research found that the area experienced almost no tree cover loss from 2000-2012.
Much of the Sundarbans’ mangroves are designated as protected areas.
Yet it’s clear that these conservation methods of the past — protecting nature from people — won’t suffice in the future. Establishing a nature reserve does nothing to stop rising seas. What’s needed now is a new approach, one that also invests in mangroves for people’s sake — in this case as a first-line defense against storms and rising seas.
It will require reining in climate change by reducing emissions, creating a buffer zone between mangroves and the growing populations around them to give them room to retreat, and implementing urban planning measures that limit development along vulnerable coasts. The Sundarbans’ mangroves have protected people for generations. Now it’s time for us to start protecting them.
RESEARCH NOTE: This analysis covered the Sundarbans’ mangroves and the four districts surrounding them, a total land area of 4.8 million hectares.