Millions of people in the Asia-Pacific region could be forced from their homes and suffer increasing disease, cyclones and floods caused by global warming. Image: iStockphoto

SYDNEY: Millions of people in the Asia-Pacific region could be forced from their homes and suffer increasing disease, cyclones and floods caused by global warming, scientists warned today.

Climate change will seriously threaten regional human security and national economies this century, according to a report by Australia's national research agency, the CSIRO.

"Chronic food and water insecurity and epidemic disease may impede economic development in some nations," the report says.

"Degraded landscapes and inundation of populated areas by rising seas may ultimately displace millions of individuals, forcing intra- and inter-state migration."

The report, commissioned by a coalition of environmental, aid, church and development groups, analyses predictions of temperature increases of up to 2°C by 2030 and up to 7°C by 2070.

Scientists blame global warming on greenhouse gases such as carbon dioxide, produced mainly by the burning of fossil fuels including coal and oil, for causing rising temperatures worldwide.

"Rapid growth in large regional economies such as China and India has elevated human prosperity," the report says. "However, unless ultimately decoupled from fossil-fuel use, such growth also threatens to exacerbate the climate challenge."

The CSIRO says that remaining below the generally accepted threshold for 'dangerous' climate change of about 2°C would require global greenhouse gas emissions to be reduced by 30 to 55 per cent below 1990 levels.

"If you don't, if you did nothing, you're likely to blow right past it," said Benjamin Preston, key author of the report.

Temperatures are likely to rise more quickly in the arid areas of northern Pakistan and India and western China, according to the report.

But the region will also be affected by a rise in the global sea level of up to 16 cm by 2030 and by up to 50 cm in 2070, along with regional variables.

Preston said two studies contained in the report estimate that a sea-level rise of a metre would displace between 75 million and 150 million people in the Asia-Pacific region.

Most at risk are the low-lying river deltas of Bangladesh, India, Vietnam and China, as well as the small Pacific island states.

Changing patterns of temperature and rainfall would also cause a shift in the distribution of dengue and malaria-carrying mosquitoes, likely exposing millions more people to such diseases by the end of the century.

"Higher temperatures may reduce the risk of cold-weather mortality, but increase heat-related mortality, while increased flooding and intensification of tropical cyclones would increase climate-related injuries and deaths," the report says.

The aid groups that commissioned the report said it was a wake-up call for Australia, one of the world's worst polluters on a per-capita basis.

"Climate change will fundamentally change the way we aid the world's poor," said World Vision Australia chief executive Tim Costello, a non-government aid agency. "It will undermine the value and impact of current aid spending and will lead to far greater calls for assistance from those hurt most."

Environmental and rights activists also called on the government to prepare to accept environmental refugees fleeing small Pacific island states hit by rising sea levels.