A new report by the bank released in Sydney, "Economics of Climate Change in the Pacific", showed that losses would range between 2.9 per cent and 15.2 per cent of annual gross domestic product by 2100.
The Pacific contains some of the smallest nations on Earth and there are growing fears that global warming and rising seas threaten their very existence, with some of them atolls barely a metre above sea level.
"It is critical that countries contributing to the problem of climate change step up to assist Pacific friends and neighbours in the fight to protect their countries against natural disasters, crop losses, and forced migration," Yao said.
"Our findings show that if not adequately addressed, climate change could overturn the region's development achievements."
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Yao did not say which countries were being referred to but the United States, China, India, Australia and the EU are among the world's major polluters.
East Timor's GDP is predicted to drop by up to 10 per cent, followed by Vanuatu (6.2 per cent), Solomon Islands (4.7 per cent), Fiji (4.0 per cent), and Samoa (3.8 per cent).
Under a medium emissions scenario, Fiji, PNG, Samoa, Solomon Islands, East Timor and Vanuatu could see temperatures rise by 2-3 Celsius (3.6-5.4 degrees Fahrenheit) by 2070, the report said, which could lead to significant decreases in rain-fed agriculture, reduced fish catches, widespread coral bleaching, and falling tourism numbers.
It recommended policy leaders take urgent action to mainstream climate change mitigation into development planning and develop forward-looking strategies.