The UN will hold a once-in-a-decade meeting on disaster risk reduction this weekend, with policymakers gathering in tsunami-struck Japan after warnings that the cost of climate change-related calamities could bankrupt future generations.

The meeting will review what lessons have been learned since the last conference, which came months after a quarter of a million people died in the December 2004 Indian Ocean tsunami.

It comes after a report by the UN Office for Disaster Risk Reduction (UNISDR) said economic losses from disasters around the world total an average $250 billion to $300 billion annually.

"We are playing with fire," UN Secretary-General Ban Ki-moon warned earlier this month.

"There is a very real possibility that disaster risk, fuelled by climate change, will reach a tipping point beyond which the effort and resources necessary to reduce it will exceed the capacity of future generations," he said.

The conference will open in the northeastern city of Sendai on Saturday, days after Japan marked the fourth anniversary of a 9.0-magnitude earthquake. The undersea quake on 11 March 2011 triggered a tsunami and a nuclear disaster, killing around 19,000 people.

Ban, who will attend the gathering, has highlighted the rise in extreme weather as global warming has accelerated over the past 10 years.

"Disaster risk reduction is a front-line defence against climate change and it is essential for sustainable development," he said in New York on Wednesday.

Margareta Wahlstrom, the United Nations' head of disaster risk, told AFP in a recent interview that progress had been made in mitigating the human cost of large-scale natural catastrophes.

"One of the things that has clearly improved (in the past decade) is the spread of early-warning systems... that demonstrated it can save lives," she said.

But there are several areas that need work, she added, citing public education as an example.

Post-disaster reconstruction is a long-term task, she said, taking at least a decade in many cases, including the 2004 Indian Ocean tsunami and the 1995 mega earthquake in Kobe in western Japan, she said.

"If you go back and talk to people in Kobe today, and last year in India, anywhere, 20 years after the disasters in these cases, people still feel they are incomplete because of the social havoc," she said.

"There's too little effort to put together the lessons learnt" about the complexity of reconstruction which is "very expensive" and "always full of frustrations," she said.

The five-day conference is expected to be attended by about 20 heads of state or government and dozens of ministerial-level delegations.

With hundreds of NGOs and interest groups also involved, organisers are expecting around 40,000 people in Sendai, offering a potential $200 million windfall to the region, including from associated tourism.

Miki Nakamura, a 39-year-old mother of four small children, who last year returned to Fukushima prefecture after three years of evacuation, said she hoped visitors "will see how things have improved here thanks to efforts made by residents".