About 24 000 inhabitants of the low-lying Mekong Delta in Vietnam , which has an estimated population of 18 million, are forced to leave the area due to global warming every year.
The Mekong Delta is one of the most agriculturally productive regions in the world and is renowned for exports of rice, shrimp and fruit.
In 2013, Alex Chapman, a research fellow in human geography at the University of Southampton and Van Pham Dang Tri, head of the department of water resources at Can Tho University, carried out research on agricultural yields in the An Thanh Dong region of the delta.
“We soon realised that virtually no farmers of An Thanh Dong had any yields to report. The commune had lost its entire sugarcane crop after unexpectedly high levels of saltwater seeped into the soil and killed the plants,” Chapman said.
In 2015/2016, the situation was exacerbated by the worst drought in a century, which caused saltwater to intrude more than 80km inland, and destroyed at least 1 605km2 of crops.
In one of the worst affected provinces, Kien Giang, with a population of 1,7 million people, the net migration rate increased substantially with about one resident in every 100 leaving.
In addition to wanting to escaping poverty, there was a range of climate-linked drivers behind migration in the delta, according to the research findings.
These included homes literally falling into the sea as the coast was becoming eroded in the south-western part of the delta. In some places 100m of coastal belt has been lost in a year.
In addition, hundreds of thousands of households had been affected by the intrusion of saltwater as the sea rose, with only a small number of people able to switch their livelihoods to saltwater tolerant commodities.
Others had been affected by the increased incidence of drought.