Climate change controversy: Its impacts and opportunities

Michael Richardson ,  Singapore   |  Thu, 07/10/2008 10:14 AM  |  Opinion

We know that the world is gradually warming. Most scientists agree this is due to man's activities, particularly the burning of fossil fuels like coal, oil and natural gas, and the release of huge amounts of carbon dioxide and other greenhouse gas emissions into the atmosphere.

However, there is debate over the rate of climate change and some uncertainty about its impact. Even so, the World Health Organization is worried that climate change endangers human health in fundamental ways.

While the warming of the planet may be gradual, the effects of extreme weather induced by climate change -- more storms, floods, droughts and heatwaves -- will be acute and immediate.

But the consequences won't be evenly distributed. Scientists predict that developing countries, particularly those with big populations in Asia and Africa, and small, low-lying island states such as those in the Pacific and Indian oceans, will be first and hardest hit.

The WHO is concerned that climate change will further degrade the basic determinants of health: Water, air, food, shelter and freedom from disease. 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, and more frequent droughts and floods are likely to reduce crop yields in many areas.

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 already affects four out of every ten people. Shifting rainfall patterns, increased rates of evaporation and melting of glaciers, combined with population and economic growth, are expected to raise the number of people living in water-short regions to between three and six billion by 2050, from about 1.5 billion in 1990.

Increases in malnutrition are projected to be especially severe in countries like China and India where large numbers of people depend on rain-fed subsistence farming.

Malnutrition, much of it caused by periodic drought, 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. Approximately 600,000 deaths occurred worldwide from weather-related natural disasters in the 1990s, nearly all 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 and floods, like those that struck Myanmar and southern China recently, are already among the most frequent and deadly forms 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 approximately 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 centers.

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.

It says that 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 like malaria, and dengue and Chikungunya fever, that are transmitted by mosquitoes or other insects. Malaria kills almost one million people each year, mainly in Africa and Asia. The WHO estimates that there may be 50 million cases of dengue infection annually, chiefly in the tropics. Some 500,000 case require hospitalization 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, favors 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.

The aim is to find ways to protect health in a hotter world with more extreme weather. One safeguard is to strengthen basic public health services.

In Asia, this helped cut the number of reported dengue fever cases to under 345,000 cases in 2005, from over 760,000 in 1990.

But it will be difficult to sustain this progress if the demands on government resources multiply as climate change exacerbates other challenges to global stability and economic growth.

The writer, a former Asia editor of the International Herald Tribune, is an energy and security specialist at the Institute of South East Asian Studies in Singapore.

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