Global Warming: Causes and Impact on Health, Environment and the Biodiversity Research Paper

Abstract

Global warming refers to the increase in the earth’s surface temperature which is mainly due to human activities, such as the burning of fossil fuels, large-scale deforestation, and increasing industrial activities. Linked with this warming are climatic changes. Because of the negative impacts of global warming on human beings and on ecosystems, it is the most important environmental problem the world faces today. There are several steps that have been taken and there are also much more steps that need to be taken by the government, industries, and general public to reduce the emission of greenhouse gases. This paper briefly discusses the sources of greenhouse gases and causes for global warming. It also gives an account of the impact of global warming on health, the environment, and biodiversity.

Introduction

Global warming is defined in simple terms as the increase in the average temperature of the Earth’s surface including the air and oceans in recent decades and if the causes of global warming are not controlled then it is predicted to continue to increase resulting in serious problems not only to the environment but also to all living organisms. Scientists estimate that global average air temperature near Earth’s surface raised 0.74 ± 0.18 °C (1.3 ± 0.32 °F) in just last one century. According to the Intergovernmental Panel on Climate Change (IPCC), “most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations,” (IPCC, 2007). These gases absorb infrared radiation emitted by the Earth’s surface and act as blankets over the surface keeping it warmer than it would otherwise be.

Though global warming is not a new phenomenon, it has been pointed out that since the industrial revolution, global temperatures have been increasing gradually. Natural phenomena also contribute to global warming. For instance, solar variation together with volcanoes has probably had a small warming effect from pre-industrial times to 1950, but a cooling effect since 1950. Climate models referenced by the IPCC project that global surface temperatures are likely to increase by 1.1 to 6.4 °C between 1990 and 2100. In fact, this range of values reflects the use of differing scenarios of future greenhouse gas emissions and results of models with differences in climate sensitivity. Though many studies have tried to predict the global climate change to a period up to 2100, it is expected that warming and sea-level rise will continue for more than a millennium even if greenhouse gas levels are stabilized (IPCC, 2007).

Causes of global warming

Several studies provide more than enough evidence that global climate change can be a serious cause of concern to each one of us and also for the coming generations if the present trend continues. These changes include sea-level rise and changes in rainfall patterns. In some parts of the world, changes may be in the form of the frequency and intensity of extreme weather events. In addition, there may also be changes in agricultural yields, glacier retreat, reduced summer stream flows, species extinctions, and increases in the ranges of pests and disease vectors.

The Greenhouse gases

Greenhouse gases keep our planet earth warm. It is not surprising to note that man’s increasing needs have simultaneously increased a load of greenhouse gases in the atmosphere. The burning of fossil fuels releases many harmful pollutants particularly greenhouse gases into the atmosphere and contributes to global warming. Increases in greenhouse gases in the atmosphere increase the earth’s temperature and results in the melting of glaciers and ice sheets (Meehl, et al. 2005). Greenhouse gases also exist naturally in the atmosphere, heating the earth by trapping energy to remain on the earth’s surface that has originally come from the Sun. This process is described as the greenhouse effect. Greenhouse gases are released by the exhausts of motor vehicles. The cutting down of rain forests also releases carbon dioxide, which is a greenhouse gas and causes global warming.

Ever since the Industrial Revolution, the amount of greenhouse gases in the air has been increasing and is resulting in a gradual increase in global temperature. This is thought to be due to human activities. During the last fifty years, mankind has also introduced CFCs, which not only damage the ozone layer but also act as greenhouse gases. The ozone layer is a protective layer present in the atmosphere and has an important role in filtering the harmful radiations of the sun from reaching the earth’s surface (Jacobson, 2004). The most important among these “greenhouse gases” is water vapor, which is responsible for about 96 to 99 percent of the greenhouse effect. Among the other greenhouse gases (CO₂, CH₄, CFCs, N₂O, and O₃), the most important is CO₂, which contributes only 3 percent to the total greenhouse effect (Ellingson, et al. 1991). The manmade CO₂ contribution to this effect may be about 0.05 to 0.25 percent (Jaworowski, 1999).

Carbon Dioxide

Greenhouse gases that aggravate global warming also include carbon dioxide, methane, and nitrous oxide. Carbon dioxide (CO₂) is produced naturally through breathing or respiration, decay of plant and animal matter, and natural forest fires. However, if this was the only source of CO₂, then nature had its own mechanism to maintain a balance with the help of natural sinks like forests and the ocean. But today, since man-made sources of carbon dioxide have increased the amount of CO₂ in the atmosphere, nature finds it difficult to clean up this gas. The man-made sources of CO₂ include the burning of fossil fuels, changes in land use, particularly deforestation, biomass burning, and the increased industrial and vehicular emissions. The natural sinks of carbon dioxide include oceans, and plants, especially forests, through photosynthesis (Jacobson, 2004).

Carbon dioxide is the most important man-made greenhouse gas. According to the Intergovernmental Panel on Climate Change (IPCC), ever since the industrial revolution, carbon dioxide levels have gone up by 31 percent (NASA Facts, 2002). It is estimated that the global atmospheric concentration of carbon dioxide has increased from a pre-industrial value of about 280 ppm to 379 ppm in 2005. Studies have revealed the fact that the atmospheric concentration of carbon dioxide in 2005 exceeds by far the natural range over the last 650,000 years (180 to 300 ppm) as determined from ice cores. In recent years, cores of ice drilled in the Antarctic and Greenland ice sheets have provided extremely valuable evidence about the earth’s past climate, including the tempo of an orbital cycle called precession (Ruddiman, 2005). Although there is year-to-year variability in growth rates, the annual carbon dioxide concentration growth rate was larger during the last 10 years (1995 – 2005 average: 1.9 ppm per year), than it has been ever since the beginning of continuous direct atmospheric measurements (1960 – 2005 average: 1.4 ppm per year) (IPCC, 2007).

According to the computer predictions, contrary to the global warmers’ computer predictions, the concentrations of carbon dioxide in the atmosphere, the most important among the man-made greenhouse gases, were out of phase with the changes of near-surface air temperature, both recently and in the distant past. This is clearly seen in Antarctic and Greenland ice cores, where high CO₂ concentrations in air bubbles preserved in polar ice appear 1,000 to 13,000 years after a change in the isotopic composition of H2O, signaling the warming of the atmosphere (Jaworowski, et al.,1992).

Methane

Methane (CH₄) is another major greenhouse gas. It is produced naturally in wetlands when organic material decays, and also by termites. Anthropogenic sources of methane include the growing of rice, cattle farming, fossil fuel burning, and the disposal of household waste in landfill sites (Jacobson, 2004). According to the Intergovernmental Panel on Climate Change (IPCC), since the industrial revolution, methane levels have increased 151 percent (NASA Facts, 2002). Studies have found that the global atmospheric concentration of methane has increased from a pre-industrial value of approximately 715 ppb to 1732 ppb in the early 1990s, and is 1774 ppb in 2005. This comparison points out that there is a tremendous increase in methane concentration in recent years. As determined from ice cores, the atmospheric concentration of methane in 2005 exceeds by far the natural range of the last 650,000 years (320 to 790 ppb). However, the growth rates have declined since the early 1990s, consistent with total emissions (sum of anthropogenic and natural sources) being nearly constant during this period. Hence it can be said without any doubt that the observed increase in methane concentration is due to anthropogenic activities, mainly agriculture and fossil fuel use (IPCC, 2007).

Nitrous Oxide

Nitrous oxide (N₂O) is a greenhouse gas naturally produced by oceans and by lightning strikes, but humans have increased its abundance by the production of nylon, nitric acid, and through agricultural practices and biomass burning (Jacobson, 2004). The global atmospheric nitrous oxide concentration increased from a pre-industrial value of about 270 ppb to 319 ppb in 2005. The growth rate has been approximately constant since 1980. More than a third of all nitrous oxide emissions are anthropogenic and are primarily due to agriculture (IPCC, 2007).

Chlorofluorocarbons

Chlorofluorocarbons (CFCs) are a group of man-made substances containing chlorine, fluorine, and carbon. They were invented in the 1930s for use in fridges, but have other uses, including aerosols. These are also classified under greenhouse gases (Jacobson, 2004). Unfortunately, CFCs – the same human-produced compound that acts as a greenhouse gas in the lower atmosphere – destroy ozone. This can result in holes in our upper ozone layer as seen over Antarctica where cold temperatures, atmospheric circulation, and other factors combine to ‘draw’ these ozone holes (Conjecture 2007).

It is believed that the main reason for global warming is the man-made emissions of greenhouse gases, from the increased use of fossil fuels. The extra greenhouse gases in the atmosphere trap more energy and therefore enhance the greenhouse effect further increasing the warming effect.

Biomass burning

Biomass burning releases greenhouse gases such as CO₂, CO, CH₄, NO_x, SO₂, C₂H₆, C₂H₄, C₃H₈, C₃H₆, and aerosol particle components. Though the Kyoto Protocol of 1997 did not consider controlling biomass burning as a strategy for slowing global warming, today it has become important to think about controlling biomass burning. While aerosol particles emitted during burning may cause a short-term cooling of global climate, longer-lived greenhouse gases may cause warming or nullify the cooling effect after several decades. Studies have found that reducing biomass burning may cause short-term warming but long-term cooling or no change in temperature. Although the eventual cooling may not appear for many years, its magnitude may be as large as 0.6 K after 100 yr. As a future prediction, much of this reduction would be due to eliminating future increases in CO₂ from biomass burning. However, it is important to note that the greatest long-term benefit in reducing biomass burning would be from the reduction in permanent deforestation. Even though controlling biomass burning may not be so competent at slowing global warming in terms of the speed and magnitude of its effect, as controlling fossil-fuel black carbon, it is essential to address multiple causes of warming at the same time (Jacobson, 2004).

Impact of Global Warming

Several scientists consider that changes in the climate will probably result in more hot days and fewer cool days. According to the IPCC, land surface areas will increase in temperature during the summer months much more when compared to the ocean. The mid-latitude to high-latitude regions in the Northern Hemisphere– areas that include the Continental United States, Canada, and Siberia– will be the areas where temperatures will be highest. These regions could go above mean global warming by as much as 40 percent (NASA Facts, 2002). When the Earth warms, the oceans will warm and expand resulting in an increase in the level of the sea. This will in turn trigger the melting of ice sheets in Greenland and Antarctica. Sea levels have been rising by 1-2 millimeters (mm) each year for the past 100 years. Current predictions suggest that the sea level may rise by half a meter in the next 100 years.

Flooding

The increase in sea level increases the chances of floods. This will be a risk especially in the low-lying coastal areas of the world such as the Netherlands and Bangladesh. In addition, important fisheries would become threatened and coastal ecosystems damaged. For instance, in Britain, East Anglia and the Thames Estuary will be mainly at risk from flooding as sea levels increase (Buchdahl, et al. 2002).

Biodiversity

Global warming is a major threat to biodiversity, but few researchers have assessed the magnitude of this threat on a global scale (Malcolm, et al. 2006). As global warming increases, habitats for many plants and animals will change, depriving them of the homes and niches to which they have adapted. These organisms will go in search of suitable places for shelter. One of the best examples is that of the monarch butterflies, which could lose their wintering habitats in the mountains of Mexico, and polar bears could be affected by the loss of sea life. Many species will not be able to travel fast enough to keep up with shifting habitat ranges and may end up in life-threatening situations or may even face death before their destination. As a result, many species will become extinct. A scientist has projected that up to 60% of northern latitude habitats could be affected by global warming. Habitats all through the United States, from the spruce and fir forests of Maine to the mangrove swamps of coastal Florida could be significantly altered (biodiversityproject.org, N.D; Malcolm and Markham, 2000). The global warming trends also had significant impacts on habitat loss, indicating that global warming could increase extinction rates (Malcolm and Markham, 2000).

Human health

The heating of the atmosphere can put pressure on human health through several routes. Prolonged heat can enhance the production of smog and the dispersal of allergens. This may damage the respiratory system. Beyond increasing the vector-borne illnesses, global warming may also elevate the incidence of waterborne diseases, including cholera (Epstein, 2000).

Conclusion

In conclusion, global warming is a serious problem and has the potential to radically affect the long-term persistence of terrestrial species. Strong and effective action to reduce greenhouse gas emissions is critical to minimize the potential impacts of global warming. An increase in global temperature means that a total disturbance in human health and all forms of life. Anthropogenic activities are mainly responsible for global warming. However, every individual must take charge of this issue and take corrective steps to prevent global warming and safeguard the planet earth. This will not only help to prevent human health problems but also every life on the planet earth.

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