The Asia Pacific region is home to over 60% of the world's people, of which according to the United Nations two-thirds of whom live in extreme poverty. With such large proportion of the current population living in poverty, climate variability already has a significant impact on the health and wellbeing of people across Asia. Climate change exacerbated natural disasters, health problems and threats to water and food security will undoubtedly affect the lives of those who are without social and economic resources to adapt to climate change.

Infrastructure and housing is extremely vulnerable to climate change as many people live in environmentally marginal areas. According to the New Economics Foundation, more than 60% of Asians will be living in urban areas by 2015. The World Bank estimates that between 25-40% of all urban inhabitants in developing countries live in slums, with little or no access to clean water, sanitation or refuse collection. As global temperatures increase, cities with limited sanitation, and stressed water and waste systems are likely to become hotspots for diseases such as gastroenteritis (ibid).

In Bangladesh, around half of the country's population lives in areas less than five meters above sea-level. The Asian mega cities of Shanghai, Bangkok, Jakarta, Bombay and Manila are all built on low-lying coastal areas. The IPCC forecasts that mean sea levels will rise by approximately 80cm between 1990 and 2080. The combined effects of storm surges and elevated peak tides will particularly threaten communities of people living in low-lying areas.

According to major re-insurance company Swiss Re, 90% of the world's climate related disasters occur in Asia. The human cost has been the death of half a million people from climate related events since 1970 (ibid).

The New Economics Foundation considers water stress to be a major impact of climate change with some of Asia's major rivers such as the Tigris, Euphrates, Indus and Brahmaputra projected to fall by as much as a quarter. In the short term, the Himalayan glaciers have already retreated by 67% since 1990, and further summer glacial melt could increase summer river flow and floods over the next few decades (DFID). While flooding increases the likelihood of contamination of fresh water supplies, this pattern would be followed by a serious reduction in flows thereafter as glaciers permanently retreat. The trend of glacial retreat and reduced rainfall combined with the growing concentration of Asia's population in urban areas and higher per capita water demands, could prove catastrophic if freshwater reserves are exhausted (New Economics).

These changes in water security and environmental flows will not only affect health of the people of Asia, but also agriculture yields for the domestic and export market. This is an international issue with the United Nations Food and Agriculture Organisation estimating that climate change could cost 65 developing countries about 280 million tons in lost cereal production, equivalent to about 16 percent of agricultural output. Across the developing world, climate change could potentially reduce the amount of rain-fed land by 11 percent by 2080. A United States Department of Agriculture study indicates that initially staple crop yields may rise but, as temperature increases beyond 1.2 degrees, yields will begin to decrease. The IPCC has already recorded a temperature increase of 1 degree since 1970 in temperate Asia and many other studies indicate reductions in yields due to reduction in rainfall and increased temperatures:

• In India, a temperature rise of 2ºC could lower yields of staple crops, wheat and rice by 10% and reduce farm revenues by up to 25% (Springerlink)
• The IPCC reports that marine products will be affected by increasing frequency of El Niño events, causing declines in catches along the coasts of south and southeast Asia, affecting food security and fish exports in countries such as Thailand, Vietnam and Cambodia.
• Scientists from the Manila based International Rice Research Institute found that for each degree in temperature increase, there is predicted to be a 10% reduction in rice yield.
  See also: Geo Year Book 2006

The IPCC anticipate the incidence of epidemic potential of malaria, schistosomiasis, and dengue and the likely spread of these diseases to new regions on the margins of presently endemic areas in tropical Asia. Water-borne and water-related infectious diseases, which already account for the majority of epidemic emergencies in the region, are also expected to increase when higher temperatures and higher humidity are superimposed on existing conditions and on projected increases in population, urbanisation,water contamination and other factors (ibid).

According to the Intergovernmental Panel on Climate Change (IPCC), daily mortality and morbidity increases during very hot weather in Asia. Older age cohorts and the urban poor are most vulnerable. In May 2002, in the state of Andhra Pradesh temperatures rose to 48.88°C, resulting in the highest one-week death toll on record. Given the IPCC Third Assessment Report projections of surface temperature increase of 1.4 to 5.8ºC from 1990 to 2100, it is likely that heat related mortality and morbidity in the Asia-Pacific region will increase substantially.

Adverse health impacts in the Asia-Pacific region also result from the build-up of high concentrations of air pollutants such as nitrogen dioxide (NO2), ozone, and air-borne particulates in large urban areas. Combined exposures to higher temperatures and air pollutants appear to be critical risk factors for cerebral infarction and cerebral ischemia during the summer months (ibid). In temperate Asia, the IPCC also forecasts that an increase in the frequency or severity of heat waves would cause an increase in (predominantly cardiorespiratory) mortality and illness. Studies of urban populations also indicate that the number of heat-related deaths would increase several-fold in response to modeled climate change scenarios for 2050.

The IPCC has predicted that extreme weather events such as droughts, floods, heat waves, avalanches and windstorms will increase in frequency and/or severity during the 21st century. Four typhoons in the Phillipines in 2004 killed more than 1,600 people. An estimated three million people were affected by the storms and more than 800,000 displaced. As well as death and displacement, physical injuries arising from these kinds of events can be expected to increase as climate change worsens.