CLIMATE change could affect human health by disrupting food and fresh water supplies, disp lacing millions of people and altering disease patterns in dangerous and unpredictable woys

"Human health could be al fee ted by even quite small changes In average mean temperature. and there is the prospect of some major dis eases flourishing in warmer conditions and of more rests tant strains of infection emerging." noted the Commonwealth secretariat recently.

The populations most vulnerable to the negative Impacts of global warming or the "greenhouse effect" are tn de veloptng countries, in the lower Income groups, residents of coastal lowlands and islands, those living In semi arid grasslands, and the urban poor In the squatter settle ments, slums and shanty towns of large cities

Present strategics for tm munfzation. coping with dis ease vectors or carriers, providing safe drinking water, and Improving nutrition are all based on existing climate regimes. ecosystems, sea and solar radiation levels. These arc all expected to change, but exactly how much cannot be predicted It to. therefore, virtually impossible to adjust health and nutritional strategies to take account of possl blc climate changes.

Human can adapt to mod erate changes In temperature and to occasional extremes. But this adaptive capacity to relatively low In Infants and the elderly; it rises through childhood and adolescence to reach a maximum which can be maintained up to about 30 y^ of age Currently, the temperature In Washington, D C exceeds 38”C on an average of one day per year; it rises above 32* C about 35 days every year. "But by the middle of the next century, these figures could rise to 12 and 85 days respectively per year", according to the World Meteorological Organization. The effect of such temperature rises on human health In Washington and similar crisis throughout the world is difficult to predict. But there is no question that increased urban

heat stress could come to claim many lh«".

A changing climate would alter the ecosystems of the

or cause many diseases whether these be viruses, bacteria. parasites plants, insects or other animals (mosquitoes snails etc.) As the a>eather srarow. the boundaries of the tropics may extend into the present subtropics, and parts of temperate areas may become subtropical. As air tem peratures Increase. some dis eases will become common in regions which once rarely knew them. Death rates may also climb significantly. Bacterial viral and parasitic diseases prevalent in tropical climes, such as those caused by the tetanus bacterium, will spread

It to possible that warmer weather around the arorid will cause increases In summer diseases and decreases tn those associated with winter Diseases like hepatltto B, epidemic cerebral meningitis, poliomyelitis, cholera and bacillary dysentery flourish In hot humid weather

In a warmer climate, mosquitoes and other vectors also may migrate vertically, up Into highlands which were once too cold for them. This may be particularly hazardous In tropical highland areas where there to no natural resistance to malaria.

Changes in temperature, rainfall. humidity and storm, patterns may affect diseases borne by vectors In tow ways First, they will directly affect the vector's reproduction rate, biting rate, and the duration and frequency of human expo sure. Second, they may modify agricultural systems or plant species, thus changing the relationship between host and vector.

Development rates of malarial mosquitoes, for ex ample, increase with warmer temperatures, but these pests need wet areas In which to breed. The snall-bome disease schistosomiasis or bilharziasis to likely to increase if global warming forces increased ir rigation or causes people to migrate towards irrigation projects. And changed human migration patterns, along with increased temperature and rainfall may extend the geo

graphic rar^^of^hookworms more favourable for the props K1. of air borne and water

In the oceans toxic "red Udes' - which kill off marine life due to the proliferation of minute marine organisms called dinoflagellates — may become more frequent as temperatures rise and nutrients from agricultural fertiite era teach into rivers and coastal waters This proliferation will disrupt marine food

uS^troptoaTfisl^or^eM^ which have consumed organisms that have Ingested di

Sca-tevel rise could also spread infectious disease by flooding eraw rage and oanite tton systems in coastal cities, and IncTToer the incidence of diarrhoea tn children. The flooding of hazardous waste could head to long-term con lamination of crop lands

Rising seas may also disrupt marine habitats and aquatic food chains Since fish constitute 40 per cent of all animal protein consumed by the people of Asia, such a dto ruptton of the marine ecooys tem would affect the food supplies of many millions of people and dramatically in crease protein deficiency and malnutrition

Some of the factors contributing significantly to global warming. such as the burning of fossil fuels and the use of chlorofluorocarbons (CFCs) and halons, threaten human health In other ways too. A typical petrol-driven motor car. far example. emits carbon monoxide, sulphur and nitro-En oxides, hydrocarbons, r-level ozone, and lead, all of which are hazardous to health. For thetr part, the ozone -depleting CFCs and halons also subject humans to increased risk of skin cancer, cataracts and tower immunity to other Illnesses as a result of increased exposure to ultra violet B radiation from the sun.

Finally, changes in the availability of food and water as well as radical shifts tn disease patterns could Initiate large migrations of people, leading to overcrowding, social stress and instability.