Michael Richardson, Straits Times 12 Jul 08;
THERE is a scientific consensus on global warming and its causes, mainly man's activities.
However, there is debate over the rate of climate change and some uncertainty about its impact. There is also disagreement between leading advanced and developing economies over how to apportion the costs of countering global warming, an impasse underlined at this week's meeting of the Group of Eight, China, India and other big emerging economies hosted by Japan.
Even so, the World Health Organisation (WHO) is worried that climate change endangers human health in fundamental ways. It has identified five major health consequences of climate change.
First, farming and food production are extremely sensitive to climate variation. Rising temperatures, bigger fluctuations in rainfall as well as more frequent droughts and floods are likely to reduce crop yields. At a time of rising food prices, this is an added challenge to global food security. It also makes people more susceptible to illness.
Water scarcity affects four out of every 10 people. Shifting rainfall patterns, increased rates of evaporation and melting of glaciers, combined with population growth, are expected to raise the number of people living in water-short regions to between three billion and six billion by 2050, from 1.5 billion in 1990.
More widespread malnutrition is projected in China and India, where large numbers of people depend on rain-fed subsistence farming. Malnutrition is already responsible for an estimated 3.5 million deaths each year.
Second, more frequent extreme weather will intensify the spread of disease, as well as cause more deaths and injuries from storms and floods.
In the 1990s, some 600,000 people died from weather-related natural disasters, mainly in developing nations. Flooding in poor countries is often followed by outbreaks of cholera and other diseases when water and sanitation services, often inadequate in the first place, are damaged or destroyed.
Storms, floods and earthquakes, such as those that struck Myanmar and southern China recently, are among the most frequent and deadly of natural disasters.
Third, both scarcity of water, which is essential for hygiene, and excess water from more frequent torrential rain will worsen diarrhoeal disease spread through contaminated food and water. Diarrhoeal disease already accounts for 1.8 million deaths each year.
Fourth, heatwaves - especially in cities, which are natural heat traps - can raise death and illness rates from heart and respiratory illness. This will be a growing problem as more and more people settle in urban centres.
Recent studies suggest that the heatwave in Europe in the summer of 2003 caused an estimated 70,000 more deaths than the equivalent periods in previous years. Higher temperatures affect levels and seasonal patterns of soot, dust and natural airborne particles, such as plant pollen, which can trigger asthma.
About 300 million people suffer from this condition and 255,000 people died of it in 2005. According to the WHO, asthma deaths are expected to rise by almost 20 per cent in the next 10 years if climate change continues unabated.
Fifth, global warming is expected to spread diseases such as malaria, dengue and chikungunya fever that are transmitted by mosquitoes or other insects. Malaria kills almost a million people each year, mainly in Africa and Asia.
According to WHO estimates, there may be 50 million cases of dengue infection annually, chiefly in the tropics. Some 500,000 cases require hospitalisation and about 12,500 cases are fatal.
Warmer temperatures, higher humidity and more places where water can collect for mosquitoes to breed, such as in the tropics, are conditions that favour malaria, dengue and chikungunya transmission. Cooler countries and places, associated with higher altitudes and latitudes, have been free of these mosquito-borne diseases. But this is expected to change as temperatures rise around the world.
The WHO and other United Nations agencies are intensifying research into the likely impact of climate change on human health to find ways to protect health in a hotter world with more extreme weather conditions.
One step to take now is to strengthen basic public health services. In Asia, this helped cut the number of reported dengue fever cases to fewer than 345,000 cases in 2005, from more than 760,000 in 1990.
But it will be difficult to sustain this progress if demands on government resources multiply as climate change exacerbates other challenges to global stability and economic growth.
The writer is an energy and security specialist at the Institute of Southeast Asian Studies.
