How Bangladesh Can Tackle Rising Seas

Salt levels in the coastal soils of Bangladesh will grow with the rising seas, putting two-fifths of its farmland at risk. Can farmers stay put? Report by Tim Radford for Climate News Network.

Ganges-Brahmaputra river delta. Image: NASA

LONDON, 29 October, 2018 − By 2140, rising seas are likely to be inundating the coastal lands (that are right now home to 1.3 billion people worldwide) in Bangladesh. Much of it is a vast estuarine silt bed fed by one of the world’s great river systems; the country is among those most vulnerable to sea level rise.

But, says a new study, many of the nation’s 165 million inhabitants may not be forced to become climate refugees.

As salty water seeps into the fertile muds and sands of the estuary of the Ganges-Brahmaputra river system, farmers could lose up to a fifth of their crop revenue each year.

An estimated 200,000 farmers may have to move inland. But the lucky ones with money to make the change may compensate by switching from rice cultivation to aquaculture, according to a new socio-economic study in the journal Nature Climate Change.

The most vulnerable people will be the least resilient in the face of climate change, because they have limited resources to adapt.

“Unfortunately, this is likely to be most challenging for those farming families who have the fewest resources to begin with”, said Joyce Chen of the University of Ohio.

“My concern is that the most vulnerable people will be the least resilient in the face of climate change, because they have limited resources to adapt their farming practices or move longer distances in search of other employment.”

Bangladesh was once, notoriously, dismissed as a “basket case” by the US statesman Henry Kissinger. The low-lying terrain has always been vulnerable to the sea: in 1970, a storm surge propelled by a cyclone drove 10 metres of water over its lowlands, claiming an estimated 500,000 lives. In 1991, a six metre-high storm surge killed 138,000 and destroyed 10 million homes.

Global Threat

Melting ice caps and expanding oceans threaten coasts everywhere: an estimated 13 million US citizens could be driven from their homes to count as climate refugees. But the spectre of sea level rise driven by profligate human combustion of fossil fuels puts Bangladesh in the front line of the challenge of climate change.

Dr Chen and a research colleague assembled as much data as they could about populations, incomes, soil geography and changing climate to try to guess what rising sea levels and ever-higher soil salinity will do to the nation over the next 120 years. Their calculations found 40% of the country’s croplands at risk, with coastal residents already experiencing frequent flooding.

But many of these had found ways to adapt: rice might not flourish in saline soil, but those who had made the big switch from crops to shrimp and fish farms had actually created more employment.

Accordingly, Dr Chen and her fellow researcher report that internal migration is likely to increase by at least 25%, as many are displaced by rising tides. But migration to other countries could actually fall by 66% because the supply of new work in labour-intensive fish farms could keep the locals at home.

Persistent Risk

The coastal landscape will remain vulnerable to potentially devastating cyclones and storm surges, and this will be made worse by soil subsidence of from 10 to 18 mm a year.

Dr Chen sees her research as a test case for adaptation to climate change: other nations should take note. “The Bangladesh study offers interesting insights for governments of countries facing similar imminent threats of sea level rise,” she said.

“As internal migration patterns are expected to shift in countries vulnerable to sea level rise, ministries of planning may benefit from developing economic strategies that integrate and even leverage the expected additional number of workers coming from vulnerable areas.”

But, she warns, climate change will continue to create climate migrants. “Additional financial support from the international community may be necessary to foster resettlement programmes.” − Climate News Network