Manila, Philippines (BBN)-The economies of South Asia, home to half the world’s poor, stand to lose almost a quarter of their gross domestic product annually by the end of the century should they fail to fight climate change.

India, Nepal, Bangladesh, Bhutan, Sri Lanka and the Maldives are more at risk than any other region to natural disasters, rising sea levels and disruptive seasonal patterns, reports Bloomberg quoting a report of the Asian Development Bank.

“The added hazards from global climate change will affect them the most, making their escape from poverty even more difficult,” the ADB said, referring to a region where a third of the 1.5 billion people are poor.

Warmer temperatures could reduce rice production in India and Bangladesh.

Rising ocean levels may swallow as much as 90 percent of the Maldives and inundate cities such as Dhaka and Mumbai.

Changes in rain and snowfall could disrupt hydropower plants in Bhutan, which generates 99 percent of its electricity from dams.

Water demand in India may outstrip supply by more than 40 percent, according to the report.

The potential economic losses calculated by the Manila-based lender don’t include extreme events such as storms, floods, and droughts.

“The values could be considered lower-bound estimates,” it said.

Policy and regulatory barriers, including “perverse subsidies on conventional fossil fuels,” prevent the region from adapting. South Asia needs to do more to adopt clean-energy technologies, it said.

Other possible measures include the introduction of drought-tolerant crops, reducing water wastage, and constructing climate-resilient water infrastructure.

BBN/ANS-21Aug14-4:00pm (BST)