The study, conducted by the Mekong Adaptation and Resilience to Climate Change Project for the U.S. Agency for International Development, marks the first step of the project's aim to help communities in the four countries to develop local climate change adaptation assessments and action plans.
Considered one of the most fertile areas of Southeast Asia, the Mekong basin is known for its production of rice and maize. About 70 percent of the basin's population of 60 million people earns a living as farmers and fishers.
"Our study is producing very surprising results," said Jeremy Carew-Reid of the International Center for Environmental Management, lead author of the study, in a statement. "We've found that this region is going to experience climate extremes in temperature and rainfall beyond anything that we expected."
While climate scientists generally agree that an average annual temperature increase in the Earth's temperature to 2 degrees Celsius -- 3.6 degrees Fahrenheit -- is the critical threshold for climate change, the study indicates that some areas in the basin could experience temperature increases that are double that by the year 2050.
As a result, the Lower Mekong countries will experience "dramatic changes" in land suitability for some industrial and subsistence crops, USAID says.
"As the climate changes, decision makers will need to consider how they prepare for the future," said USAID Regional Mission Director Michael Yates.
The Mekong ARCC project, he said, aims to help promote planning for food security and economic development by using science to minimize the risks to communities and countries so they can withstand the impact of climate change on agricultural production.
"Adaptation to climate change does not just mean shifting from one crop to another," says Paul Hartman, director of the ARCC project, Climate News Network reports.
"It also means being aware of potential changes, looking out for warning signs that these changes are beginning to occur, and being prepared to respond."
Aside from the looming danger of climate change, plans to build a series of mega-dams across the river to generate electricity also pose a threat to the Mekong countries, experts say.
International Rivers, a non-government organization in the United States, says there are 11 mainstream dams and scores of tributary dams planned on the Mekong.
"By blocking the transport of sediment, the dams will contribute to even greater erosion in the fertile Mekong Delta, which is already threatened by increasing saltwater intrusion as a result of rising sea levels," Aviva Imhof, the group's campaigns director told Voice of America.