Geoffrey Lean in The Independent claims:
Rising seas, caused by global warming, have for the first time washed an inhabited island off the face of the Earth. The obliteration of Lohachara island, in India’s part of the Sundarbans where the Ganges and the Brahmaputra rivers empty into the Bay of Bengal, marks the moment when one of the most apocalyptic predictions of environmentalists and climate scientists has started coming true. ..
Two-thirds of nearby populated island Ghoramara has also been permanently inundated. Dr Sugata Hazra, director of the university’s School of Oceanographic Studies, says “it is only a matter of some years” before it is swallowed up too.
This story doesn’t seem right. While global warming has increased sea levels, the increase to date has only been a couple of centimetres, which doesn’t seem enough to submerge an island. Let’s do some checking.
First, you can confirm that Lohachara island really has vanished by using Google maps. I’ve superimposed the map view with the satellite view, so you can see that where the map shows the island, in the satellite view there is only water.
Second, when did the island vanish? India’s Telegraph reports:
Shamila and her mother never thought the sea would completely devour their tiny island of Lohachara in the Sundarbans. And then one day, it did. The family of four was forced to pack its modest belongings and head for Sagar, the largest island in west Sundarbans. In the late 1990s, more such families followed suit. …
The team first noticed that the islands were vanishing while working on a Government of India funded project in 2001. The government census was still showing a population of 5,000 in Ghorama, one of the fast submerging islands. “But we could not find the island in the satellite images. Official records showed 102 islands in the estuary, but we found only 100. Where had the other two gone,” says Hazra of the basic premise which stoked his team’s curiosity.
So some of it was still there in the late 1990s, but it was all gone in 2001.
Third, why did it vanish? According to the Indian Express:
Prof Sugata Hazra, director, School of Oceanographic Studies, said: “A preliminary survey reveals that around 7,000 people have been displaced from their original habitat in Sunderbans over the last 30 years. They have turned into environmental refugees due to the sea-level rise, coastal erosion, cyclone and coastal flooding.”
The migrants, now living in various refugee colonies, are just an indication of what is in store for the world-renowned mangrove islands, the scientists warned.
So sea level rise was just one of the factors. And sea level rise can also be caused by land sinking as well as the ocean rising. I found a scientific paper on the topic by Gopinath and Seralathan in Environmental Geology. (Yes, the same journal that published Khilyuk and Chilingar‘s tripe.)
Gopinath and Seralathan studied Sagar island which is just 1 km from where Lohachara used to be, so their conclusions apply to Lohachara as well. They found that reduced flows in the river were causing sediments to be deposited further upstream instead of replacing erosion at Sagar island. Furthermore, the major cause of the relative sea level rise which made for more erosion, was land subsidence, not global warming.
So it is wrong to blame Global Warming for the disappearance of Lohachara island. This isn’t much comfort for people living on the other islands in the Sundarbans, since Global Warmingis likely to produce significant sea level rises in the future and Lohachara demonstrates that these islands are vulnerable to small rises in sea level.