Scientists meeting in the Thai capital have warned extreme weather caused by climate change will reduce fish stocks and major crops in the Mekong River Basin if countries in Southeast Asia fail to adapt. However, they also warn dam building, much of it for hydropower, is the largest single threat to fisheries that sustain millions of people.
An estimated 60 million fishermen and farmers depend on the Mekong River for its rich nutrients and abundant fish.
A new study by a group of scientists said by 2050 climate change could raise temperatures in parts of the Mekong basin twice as fast as the global average.
That would intensify extreme weather events, such as flooding, and reduce fish and crop production says study leader Jeremy Carew-Reid. He said, "In Laos alone there are some 700 species that are used by families to sustain their livelihoods. We know so little about them."
While some species will benefit from hotter climates, important crops such as coffee in Vietnam and rice in Thailand could be forced to move.
But fish in the Mekong system, the largest inland fishery in the world, cannot relocate so easily and fish farming has already reached its environmentally sustainable capacity.
Some 30,000 man-made barriers, such as hydropower dams, compound the effects of climate change, said Carew-Reid.
“When you take those in concert with climate change, we're looking at a pretty, a pretty negative scenario for fisheries in the basin,” he said.
Scientists at the study's release in Bangkok said dams and other barriers constitute the single largest threat to fish diversity and production.
Laos, controversially, is set to build the first of several hydropower dams on the mainstream of the Mekong.
Hans Guttman, chief executive officer for the Mekong River Commission, warns the extent of damage from the dams is still unknown.
He said, “How much damage is under intense speculation. And, whether all of the dams will be built according to some of the plans or whether some of them will be built and that will then cause a different level of impact, and how the benefits that are generated will be used to compensate or to deal with some of these impacts, is still very much uncertain.”
The U.S. Agency for International Development funded the study as part of its Lower Mekong Initiative.
Alfred Nakatsuma, the regional director of USAID's environment office, said, "The governments in general in these regions are very interested in climate change because the welfare of their people is at stake. And, it's better to address these activities now rather than later when they're surely going to be more costly.”
But just as economics are driving dam construction, scientists say poverty will make it harder for people to adapt to rising temperatures.