The Asia-Pacific region needs to spend about $40 billion a year to "climate proof" its economies against the impact of global warming, Asian Development Bank vice president Bindu Lohani said Monday.

Countries need to undergo "transformational change" to build resilience to climate change disasters, Lohani told the Asia-Pacific Climate Change Adaptation Forum in Bangkok.

The event itself was cancelled last year after Thailand suffered its worst floods in half a century, which killed more than 800 people and deluged hundreds of thousands of homes.

"There are going to be more such frequent natural disasters and they will complicate the challenge of achieving sustainable development in Asia," Lohani said.

"As the region's economies become increasingly linked through commercial supply chains... the impacts of such disasters are no longer confined to the place of occurrence but have wider regional and local impacts," he said, noting that the Thai floods disrupted supply chains for Japanese automakers.

Addressing some 200 delegates from around the region, Lohani said countries would have to undertake a transformational change to build societies that are resilient to climate change.

"Recent estimates indicate that roughly $40 billion will be required annually to neutralise the impacts of climate change ... through 2050, of which less than 10 percent has been available to date," he said.

"With the likelihood of the increase in the frequency and intensity of the climate-related disaster, such as floods, droughts and tropical storms, the costs of both disaster risk management and post-disaster relief and construction will further increase."

He said it cost 5-15 percent of baseline investment costs to manage climate-related risks to infrastructure, and had even climbed above 20 percent on some recent road transport projects.

"Although developed countries have agreed to mobilise up to $100 billion by 2020 for mitigation and adaptation, this impressive figure, actually we need to have it today and I think we may even need more," he said.

Thailand's vice environment minister Pithaya Pookaman said last year's floods illustrated the scale of the problem.

"The adverse impacts of climate change are among the most important challenges of our time. The severe flooding last year in Thailand is a stark indication of the magnitude of the problem which should not be repeated if we pursue a more sustainable development path," he said.

While Asia was home to a wide diversity of eco-systems, economies and climates, Pithaya stressed that it also faced a range of environmental challenges.

"Deltas are eroding, forests are cleared, coral reefs are degraded, coastal ecosystems are over-exploited, mega-cities have expanded, poverty is rampant and climate change presents a clear and present danger to our lifestyle and existence," he said.