Global warming may cause large-scale flooding after 2100, leading to water shortages and the spread of infectious diseases, according to the draft of a report to be issued next year by the Intergovernmental Panel on Climate Change.

If allowed to continue increasing after 2100, greenhouse gases may cause irreversible environmental changes, entailing heavier rainstorms, larger floods, serious droughts and crippled circulation of ocean water on a global scale, says the draft, obtained by Kyodo News last week.

The draft, drawn up by one of three working groups under IPCC, says recent mathematical modeling estimates that between 260 million and 320 million more people stand to be infected with malaria around 2080 in climate scenarios that average 3 degrees of warming by that time period.

IPCC, an international organization established in 1989, assessed scientific, technical and socioeconomic data relevant to the understanding of the risk of human-induced climate change. About 2,000 scientists from various nations have taken part in projects launched by the body.

Working Group II addresses the vulnerability of socioeconomic and natural systems to climate change, negative and positive consequences of climate change and options for adapting to it.

“Should climate change reduce food supply in areas of low food security, tens of millions of people could be placed at risk of hunger with attendant negative health effects” around 2080, it says.

“If extreme events such as heavy rainfall events, floods, droughts and cyclones increase in frequency or intensity, they would adversely impact human health through displacement of population, contamination of water and increased risk of injury and loss of life,” it says.

It says per capita water availability is anticipated to decline substantially in most countries by 2050 relative to the present due to population growth, with or without projected changes in climate.

“Differences between developed and developing countries in the factors that determine adaptive capacity suggest that developing countries have lower adaptive capacity than do developed countries,” the draft says, citing a lack of funds and technologies by developing countries. It is necessary to improve medical systems and infrastructure in both urban and rural areas to alleviate damage brought by global warming, the draft says.

It also reports that changes in glaciers and species composition have occurred as a result of greenhouse gases.

The draft will be published next March along with reports by IPCC’s two other working groups — Working Group I and Working Group III.

Working Group I assesses the scientific aspects of the climate system and climate change, while Working Group III assesses options for limiting greenhouse gas emissions and otherwise mitigating the effects of climate change.