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Here is a compilation of essay topics on ‘Climate Change’ especially written for school and college students.
Essay Topics on Climate Change
Contents:
- Essay on Climate Change and Geology
- Essay on Climate Change and Coal Mining
- Essay on Climate Change and Wetlands
- Essay on Climate Change and Aquatic Biodiversity
- Essay on Climate Change and Human Health
- Essay on Climate Change and Greenhouse Gases
- Essay on Climate Change and Diseases
- Essay on Climate Change and Agriculture
Essay Topic # 1. Climate Change and Geology:
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By climate we normally mean that it is simply related to the behaviour of the atmosphere. But it should be mentioned that climate of a region can be changed by the changes in other parts of the Earth’s surface over long periods of time.
“Thus, if the pattern of circulation of the ocean changes so as to warm some parts of the ocean surface and cool others, patterns of atmospheric moisture content, temperature, pressure and wind direction and strength will also change; if biological productivity changes so as to change the atmospheric content of carbon dioxide or methane, which are greenhouse gases, the surface temperature of the Earth will change. If ice sheets grow they will cool parts of the Earth by a latent heat effect, change patterns of wind circulation around them, increase the Earth’s reflectivity and so cool the Earth, lower the ocean level and change the ocean circulation pattern”.
These have led to think of the atmosphere, oceans and ice sheets and the biosphere as parts of the climate system, which is “strongly a coupled system, meaning that change in any one part will lead to changes in the other components”.
Geological system or Earth system is constituted broadly of core (innermost shell, 2900-6371 km depth), mantle (intermediate shell, ≡ 35-2900 km depth), and crust (outermost solid cover (up to av. ≡ 35 km depth), hydrosphere, biosphere and atmosphere Besides the atmosphere, hydrosphere, biosphere and mountain ranges are components of both climate system and part of the Earth system.
Both intrinsic causes (e.g., volcanism, tectonism) and extraterrestrial causes (e.g., solar radiation, bolide impacts, variation of the axial tilt of the Earth, eccentricity of the orbit and precession of the equinoxes) bring about changes in the climate system.
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Man also should be considered as a part of the geologic system because man is a natural animal (cf., palaeolife) and has become an important agent of denudation, landscape and climatic changes. In this article our purpose is to present a brief outline of the impact of climates on the surface geologic system during the geological history of the Earth. It is obvious that the surface and near-surface domains of the Earth will experience the impact of climate change.
The Earth was formed from the solar dusts (nebula) around 4600 m.y. ago. It is inferred that during the first ~ 200 m.y. the Earth probably was a ‘magma ocean’, a boiling ball of molten rock material. During the beginning of the Earth’s history the surface was hot and unsuitable for formation of oceans and continents. The primitive atmosphere, formed by the gases coming out (degassing) of the boiling ‘magma ocean’ is thought to have been composed of hydrogen, helium, CO, CO2, H2O, NOx, H2S and NH3.
Hydrogen being the lightest gas followed by helium escaped to the space. In the history of evolution of atmosphere and hydrosphere the ‘degassing’ hypothesis (atmospheric gases derived from within the Earth itself mainly by volcanic eruptions throughout later part of the Earth history) has been very popular. Recent thinking attributes much of the secondary atmosphere to extraterrestrial sources.
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Anyway, under the very hot climatic condition of the primitive Earth only igneous rocks were solidified from magma. Currently the oldest known rocks are from the Acasta Gneisses of the Great Slave Lake area in Northwest Territories of Canada, dated 4030-4000 m.y. (previously 3960 m.y.) based on U-Pb isotopes. Possibly the primary rocks, older than this have disappeared by re-melting.
The formation of sedimentary rocks was possible only when the hot climate became cooler, water basin was formed and the climate became suitable for weathering. The discovery of detrital zircon crystals of 4400-4200 m.y. age from sedimentary rocks (now metamorphosed) of Narryer Gneiss complex, Western Australia indicates that the proto-continental crustal source rock and water-bearing basin/ocean formed before this time (i.e. 4400 m.y. ago).
The weathering of zircon-bearing crustal source rock gave rise to zircon-bearing sediments for deposition and formation of early sedimentary rock in the ocean basin, which indicates that the Earth was relatively cool to form water in the ocean basin during the above time interval.
The oxygen isotope evidence indicates liquid or liquid-steam hydrosphere £ 250°C during 4400-4200 m.y. ago. These oxygen isotope studies of Archean chemical sediments further suggest that the Archean ocean temperature as late as ∼3500 m.y. ago was likely to be up to ca. 40°C higher than today.
The Earth has witnessed climatic changes throughout its history. The causes of climate change have been described by many authors. The climate changes have left their signature in the past rock record, particularly sedimentary rocks, the formation of which is due to surface processes and pressure-temperature-humidity conditions in the geological past and hence sedimentary rocks have a high potentiality for preserving the signatures of the climate under which they were formed.
The interpretation of the impact of climate on the geological system is based on the Hutton’s Law of Uniformitarianism or, expressed in a different way, as ‘Present is the Key to the Past’.
Essay Topic # 2. Climate Change and Coal Mining:
Mining operations of minerals is no longer an “ecofriendly” activity affecting at least of all of the components of the environment posing some serious impacts on the environment, which maybe permanent or temporary, beneficial or harmful, repairable or irreparable and reversible or irreversible. Mining and its associated activities have several impacts on the different sectors of our environment, viz., impacts on society, impacts on ecology, impacts on land, impacts on water regime and impacts on atmosphere including noise pollution.
Industrial activities bring forth a change in the terrestrial ecology and subsequent effects on air and water quality of the surrounding areas. It poses a great threat on the floral and faunal composition of the medium. In the mining areas, during the production of coal, burning and cutting down of forest covers generate carbon dioxide, methane and nitrous oxide and due to changes in land use these greenhouse gases are released into the atmosphere.
Emission of methane from coal mining is one of the important sources of powerful greenhouse gases. Removal of methane from the atmosphere by chemical reactions is very difficult. The rapid rise in methane started more recently than the rise in CO2, but methane contribution has been catching up fast. However, methane has an effective atmospheric lifetime of only 12 years, whereas CO2 survives much longer.
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In the mining environment this may be worsened by climate change. An increased temperature in mining zone influences the plant growth and human health and agricultural production may also be affected, particularly if combined with water depletion. In and around the mining industry higher concentration of CO2 should stimulate photosynthesis, particularly in C3 plants, such as rice, barley, potato, etc.
This is referred as “CO2 fertilization” because it can increase yields of C3 crops by 15 per cent under optimal situation; where in case of sorghum and millet, the production may not be affected seriously, that is why in developing countries it plays an important role in food security. So, the negative effects of climate change can be limited by changes in crops and crop varieties.
A change in hydrological cycle may result in wetter areas; a change in precipitation may also affect wetness, which then affect evapo-transpiration and cloud formation, which in turn affect precipitation. There is a very good link among climate change, water availability, food production, plant growth, and economic growth, but it is a very complex phenomenon.
Mining of minerals, especially by opencast method, is an activity, which degrades the land in many ways, and since mining is only an intermediate activity, it is the duty of the mining companies to bring the land back to the same status of utilization. The process of bringing the land back to the usable form comprises of reclamation, rehabilitation and mine closure and is theoretically a part of the mine plan.
Invariably efforts are made to reclaim the land in such a manner that the end result is better aesthetic topography with land use commensurate with the post-mining activities of the area. In most of the situations it is desirable to reclaim the land to the uses, such as, afforestation, plantation, grassland, agriculture and pisciculture in the voids or locally called khadan in case of opencast method, etc.
Land degradation is the alteration and spoiling of land rendering it worthless for any useful purpose. The degree of damages the land suffers due to mining varies with the topographic setting and the nature and extent of mining operations. Other factors contributing to the land degradation in the mining areas are the wind velocity, wind direction and the nature and intensity of rainfall.
Essay Topic # 3. Climate Change and Wetlands:
Climate change will have its pronounced effects on freshwater wetlands as well as coastal wetlands (IPCC, 2007). The decrease of wetland areas is a worldwide phenomenon and seems to progress faster than in other ecosystems. Non-climatic direct anthropogenic impacts have been more noteworthy than impacts directly attributed to climate change. The major non-climatic impacts include drainage of wetlands, water withdrawal, deforestation and land reclamation, habitat fragmentation, discharge of sewage, eutrophication and pollution, overharvesting and over exploitation and the introduction of invasive alien species.
Climate change is expected to intensify the loss and degradation of many wetlands not only because of the complex relationships and feedbacks between climate and wetlands, but also because of the likely synergistic effects of the non-climatic and climatic drivers, especially in coastal and low lying areas. It is widely accepted that climate change will increase the likelihood of potentially abrupt changes in wetlands, which can be large in magnitude and difficult, expensive, or impossible to reverse.
Climate change will have its most pronounced effects on inland freshwater wetlands through altered precipitation and more frequent or intense disturbance events (droughts, storms, floods). Relatively small increase in precipitation variability can significantly affect wetlands plants and animals at different stages of their life cycle (IPCC, 2007). Monsoon fed areas are more likely to be affected by more intense rain events over shorter rainy seasons, exacerbating flooding and erosion in catchments and the wetlands themselves.
An ecosystem is a dynamic complex of biotic communities and the abiotic environment, interacting as a functional unit. Climate change is likely to affect both the abiotic and the biotic components (from individual organisms, populations, to communities) of the ecosystems, and in turn, their whole structure and functioning. The major consequences of the climate change will depend on the temporal and spatial scales at which effects are assessed. Transitional scales pertaining to landscape-level shifts in location, morphometric and persistence of wetlands and their biota over decades to centuries.
All the biological processes are generally either enhanced or constrained by temperature. Therefore, a change in the temperature can directly regulate growth and behavioural pattern, e.g. phenology, and influence habitat preference. Thus increased temperatures may exceed the thermal tolerance for some cold water species, mainly in summer. As because species have varying tolerance ranges for temperature, changes in temperature can produce shifts in species composition that, in turn, can affect the overall metabolism and productivity of wetlands (IPCC, 2002).
The feasibility of species to migrate into the new expanded ranges will depend on both the habitat availability and the capability to move along dispersal corridors. However, both circumstances will largely depend on wetland type and on the habitat fragmentation. In fact, the degree of fragmentation of the landscape in which wetlands occur is historically unparalleled. Wetlands are increasingly isolated and disconnected.
Hence, making adjustment to rapid climate change through animal and plant dispersal becomes very difficult. Thus, climate change clearly represents an additional, significant threat to wetlands, one that will interact in complex ways with existing human-caused stresses.
Hydrology directly influences wetland ecosystem structure and functions by determining the extent of suitable habitat for species and many aspects of water quality. Precipitation and run-off regimes of a region determine the seasonal dynamics of the water volume of certain wetland.
By the middle of the 21st century, annual average run-off and water availability are projected to increase by 10-40 per cent at high latitudes and in some wet tropical areas and decrease by 10-30 per cent over some dry regions at mid-latitudes and in the dry tropics, with an increase in heavy precipitation events (IPCC, 2007). Such seasonality strongly influences the species composition that thrives in a wetland.
Therefore, a change in climate that alters the existing hydrologic regime has the potential to greatly modify habitat suitability for many species and cause significant ecological changes (IPCC, 2007). Climate changes driven by global warming has an immense impact on the hydrological cycle as well as a rise in sea level and increase in extreme events like storm surges, which will result in the enhanced erosion of shores and coastal habitats, salinization of groundwater and estuaries, altered tidal ranges in rivers and creeks, changes in sediment inputs and nutrient loads and increased coastal flooding and consequently in a decrease of freshwater availability for human and ecosystems in coastal areas.
Wetlands, such as mangroves, saltmarshes and floodplains, can play a critical role in the physical buffering of climate change impacts. Effects of climate change, on precipitation, wind patterns and the frequency and intensity of storms, have a key influence on wetlands response to climate change (IPCC, 2007).
Climate interacts with lake morphometrics and wind (which affects the depth of the epilimnion) to determine the strength and extent of thermal stratification. Due to wind-driven water mixing and photosynthetic activity the oxygen levels of the epilimnion are high, whereas the hypolimnion may undergo oxygen depletion due to decomposition of dead organic material settling from the productive epilimnion, influencing habitat suitability for many species as stated below.
Lakes will be affected by climate change through warmer temperatures, longer ice-free seasons and modifications in the hydrologic cycle. The response to climate change will largely depend on lake morphometries (surface area and depth), exposure to wind and location (altitude, latitude and elevation). Such factors will determine the occurrence, strength and duration of thermal stratification, and thus, the seasonal extent of cool and warm water habitats available for species.
Since the 1960s, epilimnion of many lakes around the world has warmed by 0.2°C to 2.0°C and the hypolimnion (which reflect long-term trends) has increased by 0.2°C to 0.7°C (IPCC, 2001). In warmer years, epilimnion temperature is higher, evaporation increases, summer stratification occurs earlier in the season and thermocline becomes shallower. In several lakes in Europe and North America, the stratified period has advanced by up to 20 days and lengthened by 2 to 3 weeks, with increased thermal stability.
The extent of ice cap for northern hemisphere lakes during the past 150 years is one of the strongest evidences of climate change. On average, from 1846 to 1995 the freeze data was 8.7 days later and the ice breakup 9.8 days earlier. The supply of water to lakes maybe differently affected by climate change depending on whether the water originates from glacier, snowmelt, rain or aquifers.
Water levels will probably increase in high latitude lakes, where climate models forecast increased precipitation, whereas water levels at mid and low latitudes are projected to decline. Fauna and flora constitute an important component of the freshwater biota. Acknowledging that, there may be complex and unpredictable changes in species composition, an overall increase in system productivity would likely be a common response to climate warming if other factors do not limit the potential for enhanced productivity.
However, if warming and eutrophication occurs together, the respiration of the whole community can easily counterbalance the primary production and the whole system becomes heterotrophic, i.e. a potential source of carbon. Global warming will modify the extent of habitat availability for cool and warm-water species.
Coastal swamps and marshes absorb wave energy, reduce erosion on estuarine shoreline, buffer the land from storms. Coastal wetlands are among the most productive ecosystems on earth. The high productivity of coastal wetlands is largely supported by nutrients delivered by freshwater run-off and the tidal mixing.
Changes in the timing and volume of freshwater run-off will affect salinity, sediment and nutrient availability and moisture regimes in coastal ecosystem. Freshwater inflows into estuaries also influence water residence time, vertical stratification and control of phytoplankton growth rates. Climate change can affect each of these variables by altering precipitation and locally driven run-off or more importantly, run-off from watersheds that drain into the coastal zone.
Hydrology has a strong influence on the distribution of coastal wetland plant communities, which typically grade inland from salt, to brackish, to freshwater species (IPCC, 2007). Coastal wetlands are also among the most altered and threatened natural systems due to multiple human pressures. Many coastal wetlands are likely to change as a consequence of projected sea level rise, increased storm and tidal surges, changes in storm intensity and frequency and subsequent changes in river flow regimes and sediment transport.
Over the next 100 years, the sea level is estimated to increase at a rate up to 2 to 9 mm per year, deposition of sediment will also increase at a much higher rate than that observed over the last century (average values, 1.3 to 2.1 mm y-1). Submergence and erosion of the substrate are causing a substantial loss of coastal wetlands. Such loss will produce negative effects in the ecosystem.
For example, coastal fisheries will be negatively affected, since wetlands are suitable habitats (nursery, feeding and living) for many fish and shellfish species. In addition, sea-level rise will lead to increasing salinity in coastal wetlands (reinforced if river discharge decreases), thereby tending to displace existing coastal plant and animal communities inland if migration is not blocked and if the rate of change does not exceed the capacity of communities to adapt or migrate.
Climate change impacts on one or more cornerstone species, however, can result in abrupt community changes. Saltwater intrusion into freshwater aquifers is also potentially a major problem. Changes in river discharges into shallow near-shore marine environments due to climate drivers will lead to changes in turbidity, salinity, stratification and nutrient availability. Of all ecosystems, however, freshwater wetland ecosystems and coastal ecosystems appear to have the highest proportion of species threatened with extinction by climate change.
Essay Topic # 4. Climate Change and Aquatic Biodiversity:
Biological diversity is identified as the number of taxa within an area, as the number of different life-history stages, the different species interactions within an area, or simply the number of individuals of a selected species or group of species and the geographic distribution of those individuals. In other words biodiversity is the variety and variability of life and its many processes.
It includes all life forms from bacteria, fungi and protozoa to higher plants, insects, fishes, birds and mammals. Biodiversity also includes countless millions of races, subspecies and local variants of species and the ecological processes and cycles that link organisms into populations, communities, ecosystems and ultimately the entire biosphere. Biological diversity exhibits at three levels viz., Genetic, Species and Ecosystem.
Genetic diversity means that species contain characteristic levels of genetic variation within and among their population, including that of extreme population. The foundation of biodiversity is genetic variation. Genetic variation affects a species physical characteristics, productivity, resilience to stress and long-term evolutionary potential.
Climate varies for reasons that are natural, such as volcanic eruptions, changes in solar output and natural changes in the orbital characteristics of the earth, which are known to have profound impacts on global change. However, there is now convincing evidence for a growing human influence on global climate. The industrial economy, through its reliance on carbon-based fuels has continued to alter the properties of the earth’s atmosphere.
In less than two hundred years, human have managed to increase the atmospheric concentrations of greenhouse gases by ca. 50 per cent relative to pre-industrial levels. Given the inertia in the energy systems and the long memory exhibited by the climate system, this human-induced climate change will become increasingly important relative to natural climate variability during the century to come. Certain naturally occurring gases, such as carbon dioxide (CO2) and water vapour (H2O), trap heat in the atmosphere causing greenhouse effect.
Burning of fossil fuels, like oil, coal and natural gas is adding CO2 to the atmosphere. The current level is the highest in the past 650,000 years. The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) concludes, “that most of the observed increase in the globally averaged temperature since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.”
The findings of the IPCC demonstrate that even if by 2050 emissions would be reduced to below half of 1990 levels, a temperature rise of up to 2°C above pre-industrial levels will be difficult to avoid. Unmitigated climate change beyond 2°C will lead to unprecedented security scenarios as it is likely to trigger a number of tipping points that would lead to further accelerated, irreversible and largely unpredictable climate changes.
Historically, earth’s climate has undergone significant changes, by way of warming or cooling. This is evident with the fossil records depicting mass extinctions of species over the past 500 million years, thus affecting a series of ecological changes. However, the present scenario is different from the previous one, as they are induced anthropogenically by emission of greenhouse gases, mainly in the form of carbon dioxide, methane, nitrous oxide, water vapour etc.
According to CBD document (2008), climate change is projected to increase species extinction rates, with approximately 10 per cent of the species assessed so far at an increasingly high risk of extinction for every 1°C rise in global mean surface temperature within the range of future scenarios typically modelled in impacts assessments (usually < 5°C global temperature rise). The impact will be mainly on wetlands, mangroves and coral reefs.
Essay Topic # 5. Climate Change and Human Health:
Climate change is likely to have a greater impact in India compared to other countries. This is due to the unique combination of its geography, varied ecological conditions, diverse population and extremely high carbon related energy dependence. Climate change is bound to affect the basic requirements for maintaining human health- clear air, water, food and freedom from diseases.
Over the last fifty years, human activities particularly the burning of fossil fuel have released sufficient quantities of carbon dioxide and other greenhouse gases to trap additional heat in the lower atmosphere and affect the global climate. In the last hundred years, the world has warmed by approximately, 0.75°C. It is predicted that over the last twenty-five years, the rate of global warming has accelerated, at over 0.18°C per decade.
Heat waves directly contribute to deaths from cardiovascular and respiratory diseases, rapidly among the elderly people. In the heat wave of 2003 summer in Europe, for example, more than 70,000 excess deaths were recorded. High temperature also raises the levels of ozone and other pollutants in the air that exacerbate cardiovascular and respiratory diseases. Pollens and other aero-allergens levels are also higher in extreme temperature regime, which can trigger asthma and other allergic complains.
Changes in the climate are likely to lengthen the transmission seasons of important vector-borne diseases and thus help to alter their geographic ranges. Malaria is strongly influenced by climate. Transmitted by Anopheles mosquitoes, malaria kills almost one million people every year. The Aedes mosquito, vector of dengue, is also highly sensitive to climate conditions. Studies suggest that climate change could expose an additional two billion people to dengue transmission by the 2080s.
Higher ambient temperature accelerates the growth of pathogens that thrive in or on food, such as, Salmonella spp. A cholera epidemic struck Peru and rapidly spread to other southern countries in 1991. This is due to the warm ocean waters in the eastern Pacific, which is termed as El Nino. A meningitis epidemic struck western Africa after a spell of hot and dry weather.
i. Aila and Climate Change:
Global climate change put a serious impact on natural system and thus intensity of high magnitude storms have increased worldwide. Rainfall becomes erratic and more concentric. Concentration of rain to few spells causes floods during peak rain and invites long duration drought and water scarcity for the rest of the seasons. Since 1891, there were 1148 depressions and cyclones occurred in Bay of Bengal, of which 216 are severe cyclonic storms.
This indicates a high frequency of cyclones at costal area, which leads to storm surge, generating high energy waves and consequent coastal erosion and flood. The recent cyclone, Aila, of 25th May, 2009 at Sundarban took a toll of 75 people from Sandeshkkhali I and II and Hingalganj block only. All the property and belonging of the local habitants are damaged. The social and economic system are so altered that many people have lost their livelihood and became ‘climate refugee’.
ii. Brown Cloud in Asia:
In 1995, Paul Crutzen, a Nobel Laureate working on ozone holes, reported that two million people in India were dying each year from respiratory disease caused by air pollution. According to the report of UN, the ‘brown cloud’ covers over south Asia spreading from Afghanistan to Sri Lanka and was three kilometers thick.
It was a cocktail of fly ash, nitrates, sulphates, black carbon, acid aerosols, soot and other pollutant spread over an area of ten million square kilometers. It is the product of forest fires, burning of agricultural wastes, fossil fuels, vehicular emissions and chullahs using wood, coal or cow dung. The cloud is cutting down direct sunlight by 10-15 per cent, reducing rain fall, increasing risks of drought and also of acid rain.
iii. Acid Rain and Human Health:
Acid rain is produced when sulfur dioxide (SO2) and/or the oxides of nitrogen (NOx) and their oxidation products react with the moisture in the atmosphere and come down to earth as rain or any other form of precipitation. Sulfur oxides are usually the main pollutants responsible for the formation of acid rain. They are produced by burning of coal, especially coal with high sulfur content, mainly in power station. Oxides of nitrogen usually originate from power station and from vehicular emissions.
Acid rain affects surface water (such as rivers and lakes) and ground water, as well as soil and vegetation resulting in changes in the chemistry and ecology of lakes, rivers and soil chemistry, productivity of plants and ultimately affecting human health.
Smoke produced by domestic fires, power stations and coal burning industries was the important pollutants but the most dangerous was sulfuric acid, flowing free in aerosol form or attached to the smoke particles. The infamous London smog (1952) developed as a result of meteorological condition which allowed the buildup of pollutants within the urban atmosphere. The sulfuric acid present in the smog aggravated breathing problems leading to 4000 deaths.
Essay Topic # 6. Climate Change and Greenhouse Gases:
The heat generate from sun and enters into the earth system. Sunlight travels through space and our atmosphere, heating up the land surface and the oceans. The warmed earth then releases heat back into the atmosphere. Heat exits the earth system as the earth’s surface warmed by solar energy, radiates heat away. However, greenhouse gases in our atmosphere allow the lower atmosphere to absorb the heat radiated from the earth’s surface, trapping heat within the earth system.
Greenhouse gases, such as water vapour, carbon dioxide, methane and nitrous oxide, are an important part of our atmosphere because they keep earth from becoming an icy sphere with surface temperatures of about 0°F. Over the past century or so, the amount of greenhouse gases within our atmosphere has been increasing rapidly, mainly due to the burning of fossil fuel, which releases carbon dioxide into the atmosphere.
Consequently, in the past one hundred years global temperatures have been increasing more rapidly than the historic record shows. Scientists believe this accelerated heating of the atmosphere is because increasing amounts of these greenhouse gases trap more and more heat and temperatures are expected to increase by another 1.8 to 5.8°C by the end of this century.
The hydrologic cycle will be altered, since warmer air can retain more moisture than cooler air. Some geographic areas will have more rainfall and some more drought and severe weather events-including heat waves and storms are expected to become more common. For these reasons, the term “climate change” is now preferred over the term “global warming.”
Alteration of the global environment by human has triggered the sixth major extinction event in the history of life and caused widespread changes in the global distribution of organisms. These changes in biodiversity deter ecosystem processes and change the resilience of ecosystems to environmental change. This has profound consequences for services that humans derive from ecosystems.
The large ecological and societal consequences of changing biodiversity should be minimized to preserve options for future solutions to global environmental problems. Strong evidence for changes in biodiversity and its ecosystem and societal consequences calls for similar international actions. The most important causes of altered biodiversity are factors that can be regulated by changes in policy like emissions of greenhouse gases, land-use change and species introductions etc.
The climate has a potential impact on human health from vector borne and waterborne infections, e.g. malaria and cholera. For example, there is currently an epidemic of cholera in northern Kenya in the wake of a severe drought. It concentrates on the impact of two possible changes to climate; increased frequency of heavy rainfall events with associated flooding and increased temperature. There have been numerous reports of outbreaks that followed flooding that led to contamination of underground sources of drinking water.
Heavy rainfall also leads to deterioration in the quality of surface waters that could adversely affect the health associated with recreational water contact. Because of rising temperatures and changing rainfall patterns, climate change is expected to have a substantial effect on the burden of infectious diseases that are transmitted by insect vectors and through contaminated water.
Essay Topic # 7. Climate Change and Diseases:
Researchers have found that there is a close link between local climate and the occurrence or severity of some diseases and other threats to human health (WHO, 2005). It is estimated that climate change contributes to 150,000 deaths and 5 million illnesses each year, and the World Health Organization estimates that a quarter of the world’s disease burden is due to the contamination of air, water, soil and food. In the last quarter of the 20th century, the average atmospheric temperature rose by about 1°F.
By 2000, that increase was responsible for the annual loss of about 160,000 lives and the loss of 5.5 million years of healthy life, according to estimates by the World Health Organization. The toll is expected to double to about 300,000 lives and 11 million years of healthy life by2020. The biggest tolls were in Africa, on the Indian subcontinent and in Southeast Asia. Most of the increased burden of death and disease were from malnutrition, diarrhoea, malaria, heat waves and floods.
But those diseases will play a minor role, at best, in many regions that nevertheless will feel the effects of global warming. What is readily apparent from these data is that developing regions of the world have been disproportionately affected by climate change relative to developed regions. Climate-sensitive diseases are among the largest global killers. Diarrhoea, malaria and protein-energy malnutrition alone caused more than 3.3 million deaths globally in 2002, with 29 per cent of these deaths occurring in the region of Africa.
Deadly diseases like the West Nile virus, cholera and Lyme disease, often associated with hot weather, are spreading rapidly throughout North America and Europe because increased temperatures in these areas allow disease carriers like mosquitoes, ticks and mice to thrive.
Therefore, we must focus our efforts on mitigating the effects of climate change, including its potential impact on the global burden of infectious diseases. Additional research is needed on the ecology and epidemiology of infectious diseases that will probably be affected by climate change. The best means for accomplishing this aim would be to incorporate research on the effect of climate change into existing infrastructures, such as the ambitious malaria-eradication program recently launched by the Bill and Melinda Gates Foundation.
It is imperative that organizations such as the WHO continue their missions of treating and preventing otherwise neglected infectious diseases, as part of a multifaceted approach in improving global health. Effective treatments and vaccines will go a long way in preventing human suffering that could otherwise occur as a result of climate change.
The impact of climate change on water availability is likely to be one of the most significant for the health of populations. Higher temperatures are hastening rates of evaporation of surface water thereby reducing the availability of fresh water. Lack of fresh water compromises hygiene and hence increasing incidence of diarrhoeal disease. On the other hand, too much water, in the form of floods, causes contamination of freshwater supplies.
Extreme events like sea level rise coupled with stronger storm surges and coastal flooding can be followed by outbreak of diseases such as cholera. Other water-borne and food-borne infectious diseases pose a great threat to public health in the tropical monsoon region.
In 1995, in eight countries of the region (Bangladesh, Bhutan, India, Indonesia, Myanmar, Nepal, Sri Lanka and Thailand), the total death toll from diarrhoea was estimated to be 1.03 million; 71 per cent and 12 per cent of the deaths occurred in India and Bangladesh, respectively. Children under five years of age are accounted for about 25 per cent of these deaths (WHO, 1996).
The cyclone Aila that lashed the city on May 25th, 2009 is an indication. Kolkata is among the world’s most vulnerable metropolises. Scientists studying the vulnerability of Kolkata from events triggered by climate change have warned that vital services, like water and electricity, are extremely susceptible to cyclonic storms and sea level rise due to its proximity to the Bay of Bengal, 80 km away from the city limit.
Due to climate change, deltas particularly Sundarbans will be threatened by flooding, erosion and salt intrusion. Loss of coastal mangroves will have an impact on fisheries. The major delta area of the Ganga, Brahmaputra and Indus rivers, which have large populations reliant on riverine resources will be affected by changes in water regimes, salt water intrusions and land loss. It is now well documented that the rise in temperature and change in humidity will adversely affect human health in India.
Heat stress could result in heat cramps, heat exhaustion, heat stroke and damage physiological functions, metabolic processes and immune systems. Increased temperatures can increase the range of vector borne diseases such as malaria, particularly in regions where minimum temperatures currently limited pathogen and vector development.
Several reports have highlighted other effects of climate change on infections. For example, El Nino since 1975, and more recently its frequency, has been shown to strengthen the relationship between the cycle and cholera outbreaks in Indian subcontinent.
According to Colwell (1996), the major rivers of the Indian subcontinent that discharge into the Bay of Bengal carry huge amounts of agricultural and industrial waste, providing nutrients sufficient to convert coastal waters to eutrophic conditions. Brackish water extends some distance upriver for all rivers. Salinities between 5 ppm and 30 ppm, which were detected in inland coastal areas and in sea water are favorable for the growth of Vibrio cholera.
In the Bay of Bengal, evidence has been found by synthesizing satellite remote sensing, in-situ hydrographic and meteorological data sets, that cholera cases occur with a rise in ocean temperature. Outbreaks during the monsoon have been substantially smaller. Colwell (1996) also indicated a possible link between outbreaks of cholera in Peru and neighboring countries and a warming El Nino/Southern Oscillation (ENSO) event.
Although the ENSO phenomenon has a substantial effect on the Indian summer monsoon, its linkage with cholera has not been investigated. In addition to enteric pathogens, climate also influences the abundance and ecology of non-enteric and other pathogens which are naturally present in the environment. The best examples of this include the pathogenic Vibrio spp., which are autochthonous in estuarine ecosystems.
Along with V. cholera, the bacteria thrive in warm waters of moderate salinity and are closely associated with aquatic invertebrates. An estimated 94 per cent and 40 per cent of deaths were due to diarrhoeal diseases and malaria, respectively that has relation with environmental factors. In Kolkata, a survey of 13 years observation on cholera revealed that gradual changes in shifting of cholera incidence with single peak (April) followed by two peaks (September- October and continued till December) in a year.
The above cholera infection periodicity has been related to climatic factors like relative humidity, temperature, rainfall, sea surface temperature, sun spot numbers along with influence of El Niño and La Niño. Therefore, with a changing climate, the geographic range of these pathogens may also change, potentially resulting in increased exposure and risk of infection for humans.
Furthermore, changes in plankton populations and other hosts for which vibrios are commensals or symbionts, would similarly alter the ecology of these pathogens that are autochthonous to the aquatic environment. Furthermore, the incidence of cholera may occasionally be surprisingly low at times when climate seems to favour cholera transmission.
We, the Indians, are facing more and more heat during summer and the temperature is increasing day by day. At the same time, the monsoon and other seasons are changing due to global warming. The changing climates affect the human health as well as the environs. As a result, emerging and reemerging diseases are coming up with a great concern.
In spite of extensive research studies, several programme launched by the government and non-governmental agencies for the protection of our earth, still, the nature is progressing in its own way. In reality, we are totally under the influence of nature. It is the nature, does harm to the mankind and also may protect us from the disaster.
Essay Topic # 8. Climate Change and Agriculture:
Climate change is undoubtedly a matter of utmost concern to the humankind as well as many other members of the biosphere and their well-being and even survival till the end of the present century may depend on how effectively the formidable challenge posed by anthropogenic greenhouse gas induced global warming can be countered.
Lack of general awareness on the issue among the general public, even many in the more enlightened section of the people and particularly among many decision makers, is widespread and perhaps underestimated. A clear understanding of the causative factors behind climate change is necessary to visualize its impact on agriculture especially in view of the fact that present day industrial-agricultural system including deforestation is responsible for generation of nearly one third of the anthropogenic greenhouse gas emissions that are responsible for global warming.
Thus, contrary to the general belief of global climate change disrupting agricultural systems, mitigation of overall agriculture related emissions of greenhouse gases is urgently necessary not only to save agriculture itself but also to protect many other vital spheres of human activities.
Fortunately, there are overwhelming and most convincing documented evidences of eco-sustainable agricultural practices that are capable of greatly reducing greenhouse gas emissions and at the same time ensure food security of the people, specifically of the poor small and marginal farmers of the developing countries like India which incidentally is a country with the largest number of hungry people in the world.
The present article deals with the climate change-agriculture interface and brings out the salient features of the climate change scenario as well as relevant features of conventional (industrial) and holistic eco-sustainable farming systems. It is primarily targeted towards readers with a broad understanding of the general environmental and agricultural issues and their socioeconomic implications on the livelihood security of small-holder farmers of the developing countries, with emphasis on the Indian situation, in particular.