CLIMATE change refers to any significant change in measures of climate. Potential effects of this climate change are likely to include more variable weather, stronger and longer heat waves, more frequent heavy precipitation events, more frequent and severe droughts, extreme weather events such as flooding and tropical cyclones, rises in sea level, and increased air pollution. Other effects may result from ecosystem shifting and disruption.Climate change is an emerging risk factor for human health. According to the third assessment report of the Intergovernmental Panel on Climate Change, Climate change can affect human health directly (e.g. impacts of thermal stress, death/injury in floods and storms) and indirectly through changes in the ranges of disease vectors, waterborne pathogens, water quality, air quality, and food availability and quality. The actual health impacts will be strongly influenced by local environmental conditions and socio-economic circumstances, and by the range of social, institutional, technological, and behavioural adaptations taken to reduce the full range of threats to health.Broadly, a change in climatic conditions can have three kinds of health impacts: those that are relatively direct, usually caused by weather extremes; the health consequences of various processes of environmental change and ecological disruption that occur in response to climate change; and the diverse health consequences traumatic, infectious, nutritional, psychological and other that occur in demoralised and displaced populations in the wake of climate-induced economic dislocation, environmental decline, and conflict situations.Climatic changes over recent decades have probably already affected some health outcomes. The World Health Organisation estimated, in its World Health Report 2002, that climate change was estimated to be responsible in 2000 for approximately 2.4 per cent of worldwide diarrhoea, and 6 per cent of malaria in some middle-income countries. Marked short-term fluctuations in weather can cause acute adverse health effects: extremes of both heat and cold can cause potentially fatal illnesses, e.g. heat stress or hypothermia, as well as increasing death rates from heart and respiratory diseases. In cities, stagnant weather conditions can trap both warm air and air pollutants leading to smog episodes with significant health impacts. These effects can be significant. Abnormally high temperatures in Europe in the summer of 2003 were associated with at least 27,000 more deaths than the equivalent period in previous years. Other weather extremes, such as heavy rains, floods, and hurricanes, also have severe impacts on health.Approximately 600,000 deaths occurred worldwide as a result of weather-related natural disasters in the 1990s; and some 95 per cent of these were in poor countries. To a large extent, a changing climate is likely to affect public health which depends on safe drinking water, sufficient food, secure shelter, and good social conditions. Reviews of the likely impacts of climate change by the IPCC suggest that a warming climate is likely to bring some localised benefits but overall the health effects of a rapidly changing climate are likely to be overwhelmingly negative, particularly in the poorest communities, which have contributed least to greenhouse gas emissions.Recent analyses show that human-induced climate change significantly increased the likelihood of the European summer heat wave of 2003; more variable precipitation patterns are likely to compromise the supply of freshwater, increasing risks of water-borne disease. Rising temperatures and variable precipitation are likely to decrease the production of staple foods in many of the poorest regions, increasing risks of malnutrition. Rising sea levels increase the risk of coastal flooding, and may necessitate population displacement. More than half of the worlds population now lives within 60km of the sea. Some of the most vulnerable regions are the Nile delta in Egypt, the Ganges-Brahmaputra delta in Bangladesh, and many small islands, such as the Maldives. Changes in climate are likely to lengthen the transmission seasons of important vector-borne diseases, and to alter their geographic range, potentially bringing them to regions which lack either population immunity or a strong public health infrastructure.Heat exposure has a range of health effects, from mild heat rashes to deadly heat stroke. Heat exposure can also worsen several chronic diseases, including cardiovascular and respiratory disease. The results can be severe and result in both increased illness and death. Heat also increases ground-level ozone concentrations, causing direct lung injury and increasing the severity of respiratory diseases such as asthma and chronic obstructive pulmonary disease. The direct effects of extreme weather events include drowning from floods, injuries from floods, and structural collapse. Potential indirect effects include aggravation of chronic diseases due to interruptions in healthcare service, significant mental health concerns both from interrupted care and geographic displacement, and socioeconomic disruption resulting from population displacement and infrastructure loss.Air quality is highly affected by weather and climate conditions. In turn, certain aspects of air quality are known to affect health. Ozone causes direct, reversible lung injury; increases premature mortality; worsens respiratory diseases such as asthma and chronic obstructive pulmonary disease; and may cause chronic lung damage. Storms and extreme precipitation events have several direct health effects. Extreme precipitation events are associated with outbreaks of gastrointestinal disease.Heat waves are already the most deadly weather-related exposure in the US. Studies suggest that, if current emissions hold steady, excess heat-related deaths in the US could go up from an average of about 700 each year currently, to between 3,000 and 5,000 per year by 2050. Climate is one of many variables known to affect the rates of vector-borne and zoonotic diseases such as vector mosquito species, which spread malaria and viral diseases such as dengue and yellow fever. Malaria, today, is mostly confined to tropical and subtropical regions. The diseases sensitivity to climate is illustrated by desert and highland border areas where higher temperatures and rainfall associated with El Nio may increase transmission of malaria. Dengue is the most important arboviral disease of humans particularly in urban settings. Between 1970 and 1995, the annual number of dengue epidemics in the South Pacific was positively correlated with La Nia conditions (i.e. warmer and wetter). In the tropics diarrhoeal diseases typically peak during the rainy season. Both floods and droughts increase the risk of diarrhoeal diseases. Major causes of diarrhoea linked to heavy rainfall and contaminated water supplies are: cholera, cryptosporidium, E.coliinfection, giardia, shigella, typhoid, and viruses such as hepatitis A.Various analyses have shown that health impacts are often the largest single contributor to the costs of environmental damages. The governments health authorities should undertake a comprehensive evaluation of the possible health implications of such changes and need to determine priorities for planning and decision-making. The health sector should be involved jointly with agricultural, meteorological, environmental, and planning agencies to ensure that health considerations are given adequate weight. But not only for these individual awareness is also needed such as lifestyle change, behavioural change, efficient use of energy, etc.