BANGKOK (Reuters) - Developing countries will need to spend as much as $100 billion annually for the next 40 years to adapt to more extreme and severe weather changes, according to a World Bank study issued on Wednesday.

The report said poorer countries would need to invest in large-scale infrastructure projects to cope with floods, drought, heatwaves and more frequent and intense rainfall if the Earth’s temperature rose by 2 degrees Celsius by 2050.

“Faced with the prospect of huge additional infrastructure costs, as well as drought, disease and dramatic reductions in agricultural productivity, developing countries need to be prepared for the potential consequences of unchecked climate change,” said Katherine Sierra, World Bank vice president for sustainable development.

Previous estimates of adaptation costs by other groups ranged from $9 billion to $104 billion, but the World Bank said the latest projection of costs are the most in-depth analysis to date of the impact of climate change.

The report gave a costs range of $75 billion to $100 billion based on two different scenarios, the first a drier world that would require less investment than wetter conditions, which would need measures such as building sea walls or deeper drainage canals.

HARDEST HIT

East Asia and the Pacific, home to some of the world’s fastest-growing economies, would be the hardest hit financially, accounting for at least a quarter of total costs, mostly due to increased urbanization, especially in coastal areas, said Warren Evans, director of the Bank’s environment department.

According to the study, the cost of adapting to a warmer world is on the same scale as the amount of aid developing countries currently receive. Aid agencies say it is essential that aid money is not cut to fund climate change initiatives.

“Any financing that comes in must be additional money,” Oxfam’s senior climate policy advisor, Antonio Hill, told Reuters. “If it’s not, then it’s just robbing Peter to pay Paul.”

Conservation group WWF voiced concern that the World Bank’s estimate was based on the assumption that the world would work together to restrict the temperature rise to two degrees.

“The commitments from developed countries in the present negotiations don’t come anywhere near this level of ambition,” WWF said in a statement, referring to global climate change talks taking place in Bangkok.

“This underlines the need for much stronger commitments on the table from developed countries, both in terms of emissions reductions and in terms of financing for climate action in developing countries.” (Editing by Martin Petty and Alex Richardson)