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 world’s 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 disease’s sensitivity to climate is illustrated by desert and highland border areas where higher temperatures and rainfall associated with El Niño 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 Niña 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 government’s 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.

Nobody knows how many species there are in the world -- or how fast they are disappearing. Fewer than 2 million have been cataloged and estimates of the total vary wildly, ranging from 7 million to as many as 80 million. The currently accepted working estimate is 13.6 million.

Biodiversity is a term applied to describe the complexity of life. It is generally measured at three levels: the variety of species; the genetic diversity found within members of the same species (what makes you different from your neighbour); and the diversity of the ecosystems within which species live. These three levels are intimately connected. Genetic diversity is essential to the prosperity of the species, giving it the resources to adapt. And the number of species within an ecosystem is closely tied to the health and size of the ecosystem itself. However it is defined, biodiversity is the stuff of life. However far we may be removed from "wild" biodiversity in our daily lives, it remains the source of our food and most of our medicines. In addition, 15 percent of our energy is derived from burning plant materials. Even in the United States, wild species contribute around 4.5 percent of GDP. Due to agricultural modernisation, changes in diets and population density, humankind increasingly depends on a reduced amount of agricultural biological diversity for its food supplies. A dozen species of animals provide 90% of the animal protein consumed globally and just four crop species provide half of plant-based calories in the human diet. FAO estimates that about three-quarters of the genetic diversity found in agricultural crops have been lost over the last century. Of 6 300 animal breeds, 1 350 are endangered or already extinct. This rapidly diminishing gene pool is cause for concern.

At least 40 per cent of the world's economy and 80 per cent of the needs of the poor are derived from biological resources. In addition, the richer the diversity of life, the greater the opportunity for medical discoveries, economic development, and adaptive responses to such new challenges as climate change Biodiversity is an immense resource, built up over 3.5 billion years of evolution. It embraces not only the number of species on Earth, but the range of habitats and genetic diversity within species as well. It is of enormous importance to humans. Of the 270 000 known plants, some 3000 are exploited for food, and between 25000 and 50000 more are used in traditional medicine. Wild plants are potential sources of new medicines and of material for genetic engineering. Biodiversity is a major attraction for tourism, and not least a lasting source of human aesthetic pleasure.

Around 1.75 million species have been scientifically described. More than half of these are insects, while vertebrates -- including fish, birds, mammals, reptiles and amphibians -- make up only 2.5 percent. But the real number is certainly far higher. Most recent estimates fall in the 7 to 20 million ranges, though a widely acceptable working estimate, used by the United Nations Environment Programme's Global Biodiversity Assessment of 1995, is 13.6 million.

Most ecologists believe that we are currently undergoing a mass extinction driven by human activities. Since 1600,484 animal and 654 plant species are known to have become extinct through human actions. But these are only the tip of a vast iceberg. Since most species are as yet undescribed, the majority of current extinctions are going unrecorded -- species are dying out before we even learn of their existence. Projections of future losses vary widely, from 2 to 25 percent of all species over the next 25 years. But even the low end of this range is 1 000 times the background rate of extinction.

The total extinction of a species is drastic and at present irreversible. But local extinctions are serious, and far more common. Data on species are far from complete, but countries and taxonomic groups with more complete information have a higher share of species threatened, so it is quite likely that as more data become available, the percentage judged to be under threat will rise. The prospects for the coming decades look gloomy. Forests are the home of between 50 and 90 percent of all land species in the world. If tropical deforestation continues at present rates for the next 30 years, it is estimated that 5 to 11 percent of forest species will eventually be lost. Wildlife habitat is becoming increasingly fragmented by human activities -- making way for cities, farms and roads. Fragmentation lowers the size of individual populations, reducing their genetic variability, and making them more vulnerable to extinction. Human barriers also make it difficult for animals and plants to migrate in response to environmental change.

At the same time, global warming will be shifting present temperature zones generally polewards and uphill. Species will have a greater need to migrate but will encounter human barriers blocking their way. Some species which prefer cold temperatures will see their natural habitats disappear completely. Meanwhile genetic engineering -- unless it is rigorously controlled -- may introduce new genes which could spread to wildlife with unforeseeable consequences. There is no doubt that genes from existing commercial crops can pass to wild relatives, and even with rigorous control measures, it is unlikely that accidental transfers could be prevented indefinitely. The extent to which this is likely to have negative impacts on the environment and biological diversity is still not known.

The Global Biodiversity Assessment found that the major threat to biodiversity was habitat loss, fragmentation and degradation, due to the need for land for farms, dwellings, industry, services, transport and leisure. Of those species that are threatened, habitat loss affects 44 percent of the bird species, 55 percent of the fishes, 68 percent of the reptiles, and 75 percent of the mammals. Other direct pressures are overexploitation of species for commercial gain, for subsistence or for sport. The introduction of alien species, pollution and climate change are all major threats. Population is a major indirect cause underlying most of these threats. Population density is closely linked with most forms of habitat loss. A sample of 50 non-desert countries in Asia and Africa where wildlife habitat loss has been estimated showed that the percentage loss tends to be highest where population density is highest. The top 20 percent of countries, ranked in terms of habitat loss, had lost an average of 85 percent of their original wildlife habitat. Their average population density was 189 people per square kilometer. The 20 percent with lowest population density had lost an average of only 41 percent of their wildlife habitat -- and their average population density was only 29 people per square kilometer.

Governments are gradually moving to give wider areas protected status, but progress is slow. Globally, in 1997, only 6.4 percent of the land area was protected. To protect the full range of species, large areas are needed, but 88 percent of protected areas in 1997 were smaller than 100000 hectares -- a square with sides of about 32 kilometers.

Biodiversity is one of the integral parts of our life as different aspect of activities. For our survival, we must be aware of the biodiversity and to withstand the mass extinctions. It is high time for Sustainable use and conservation of biodiversity unless our extinction will come soon.

HUMAN population growth is the primary threat to the world's environment. Each person requires energy, space and resources to survive, resulting in environmental losses. Our population is rapidly rising beyond the earth's ability to regenerate and sustain us with a reasonable quality of life. We are exceeding the carrying capacity of our planet, challenging the existence of several species, including our own.

When people think of human impacts on the environment, they often think in terms of total population and population growth. The scale of our activities depends on population, consumption and the resource or pollution impact of technologies; all three of these factors are steadily increasing.



Urbanisation
Rapid urban growth can bring environmental problems for cities. With many cities growing at 4 to 5% a year, provision of clean water, sewage, electricity and roads can rarely keep up with population growth. Lack of sewage treatment leads to water pollution, eutrophication and biodiversity loss in rivers and around outlets. Water demand may lower river and groundwater levels. The International Decade for Drinking Water Supply and Sanitation (1980-90) documented the growth of those without clean water in urban Africa, rising from 28 million to 31 million; those without safe sanitation rose from 38 million to 47 million.

We have transformed half the world's land for our own uses -- around 11% each for farming and forestry, 26% for pasture, and another 2 to 3% for housing, industry, services and transport. In most parts of the world, cultivated land has not expanded in line with population growth, decreasing the amount of farmland per person. The area per person has declined slowly in developed countries, from 0.65 hectares in 1965, to 0.51 hectares 30 years later. In developing countries, where population growth is faster, the area per person fell from 0.3 to 0.19 hectares over this same period.



Freshwater
Freshwater is crucial for survival, health, agriculture, industry, comfort and leisure. But freshwater sources are limited -- there is only so much to go around: the larger the population, the less there is for each person.

In 1995, some 436 million people were already suffering water scarcity or stress, causing severe development problems. There are conflicts among farmers and between rural and urban needs, and heightening tensions between countries dependent on the same resources, such as with India and Bangladesh.

The UN's 1996 population projection has estimated that, by 2050, the projected number of people suffering water stress or scarcity will have risen to 4 billion approximately.



Biodiversity
Most ecologists believe that human activities are causing mass extinction. Since 1600, 484 animal and 654 plant species are known to have become extinct through human actions. The total extinction of a species is drastic and irreversible, but local extinction is also serious, and far more common. The Global Biodiversity Assessment listed the major threats to biodiversity as habitat loss, fragmentation and degradation, due to the need for land for farms, dwellings, industry, services, transport and leisure. Of those species that are threatened, habitat loss affects 44% of bird species, 55% of fishes, 68% of reptiles, and 75% of mammals.

Population density is closely linked with most forms of habitat loss. A sample of non-desert countries where wildlife habitat loss has been estimated showed that the percentage loss tends to be highest where population density is highest. The top 20% of countries, ranked in terms of habitat loss, had lost an average of 85% of the original wildlife habitat. Their average population density was 189 people per square kilometre. The 20%, with lowest population density, had lost an average of 41% of their wildlife habitat -- and their average population density was only 29 people per square kilometre.



Forests
We lose forests at the rate of 112 million hectares each decade, an area twice the size of Kenya or France. Highly populated countries such as India and China have almost come to the end of their period of deforestation and have begun to reverse forest loss. Some of the fastest rates of deforestation are found in middle-income developing countries with strong commercial logging interests (Indonesia 2.4%, the Philippines 3.5%, and Thailand 2.6%).

A number of studies have found a strong correlation between population density and deforestation rates on national levels. A recent report by the United Nations Population Fund estimated an average loss of 1.8% of forests per year between 1980-90, where the population density was 89 people per square kilometre. Areas with slower deforestation tend to have lower population density; where there are just 34 people per square kilometre, the deforestation rate was only 0.5%.



Coastal environment
High percentages of human population and activity are located on or near coasts. Coastal areas have always been important for trade, transport and defence, containing some of the densest concentrations of human population and activities today. Nearly two-fifths of the world's populations live within 150 kilometres of a coastline. A recent assessment found that over half the world's coastlines are at risk from coastal development, with over one- third at high risk. Nearly three quarters of the world's marine protected areas are similarly threatened. In addition, human activities over vast inland areas impact coasts and coastal waters. Much of the water pollution and sediment eroded from whole watersheds is transported to the sea.



Mangroves
Mangroves cover an estimated 18 million hectares of the earth's tropical coastlines, around one quarter of the total. Mangroves host unique species, and are important nurseries for commercial marine species.

It is estimated that around half of all tropical mangroves have been destroyed. The Philippines, Puerto Rico, Kenya and Liberia have lost over 70%. Major pressures are cutting for fuel wood and timber; habitat conversion for coastal development or aquaculture (often shrimp farming); and damming of rivers which alters water salinity. Other direct and indirect causes of these pressures include: population growth, tourism and resource consumption in and around coastal areas.



Coral reefs
The world has an estimated 255, 000 square kilometres of near-surface coral reefs, constituting one of the richest resources of biodiversity on the planet. A recent study estimated that 58% of the world's reefs are threatened by human activity, almost half of these seriously so. In Southeast Asia, which has very high levels of coral and fish diversity, more than 80% are potentially at risk.

The threats to coral reefs are many: over-fishing, pushing fish stocks below their maximum sustainable yield; destructive fishing practices; and extraction. Water pollution from industry, sewage, fertiliser, and sediment eroded from deforested or badly farmed areas, all wash into the sea, reducing light levels and physically smothering corals.



Marine environment
Oceans make up seven-tenths of the planet's surface, and we use an estimated 8% of their total primary productivity. Yet we have fished up to the limits or beyond, altering the ecology of a vast range of marine species.

Assessments from 1999 found that 44% of major fish stocks have already been exploited to their maximum sustainable yield. Another 16% are over-fished, meaning future catches will fall unless remedial action is taken.

Pollution from oil spillages, runoff and rivers includes sewage, industrial effluents, fertilisers, pesticides and herbicides. Air pollution is the source of one-third of marine pollutants.

There are now around 50 known "dead zones" with no or low oxygen. Most of these have appeared over the last half-century, and are blamed on excessive influx of nitrogen and phosphorus from farming and sewage. The dead zone in the Gulf of Mexico is 4,144 square kilometres, doubling in size since 1993.

We need to voluntarily limit our growth, and promote contraceptive use, before nature controls our population for us with famines, droughts and plagues. Our children's future depends on us.

How people preserve or abuse the environment largely determines whether living standards improve or deteriorate. Population growth, urban expansion, and resource exploitation do not bode well for the future. Without practicing sustainable development, humanity faces a deteriorating environment and may even invite ecological disaster.