Global Warming: A Deadly Threat for Human Life

Global Warming refers to the sustained increase in the average temperature of the earth's atmosphere. Human activity contributes to this change through the buildup of heat-trapping greenhouse gases. Over time, this increase may be sufficient to cause climatic change, including raising sea levels, altering precipitation patterns and changing water supplies and crop yields. It is also an increase in the near surface temperature of the Earth. Global warming has occurred in the distant past as the result of natural influences, but the term is most often used to refer to the warming predicted to occur as a result of increased emissions of greenhouse gases. Scientists generally agree that the Earth's surface has warmed by about 1 degree Fahrenheit in the past 140 years.

The Intergovernmental Panel on Climate Change (IPCC) recently concluded that increased concentrations of greenhouse gases are causing an increase in the Earth's surface temperature and that increased concentrations of sulfate aerosols have led to relative cooling in some regions, generally over and downwind of heavily industrialized areas. Global warming has occurred in the distant past as the result of natural influences, but the term is today most often used to refer to the warming some scientists predict will occur as a result of increased anthropogenic emissions of greenhouse gases. The usual method to research about this phenomenon is to measure the surface-air temperature over time. Some people blame the nature for the temperature increase while other points at human causes, such as our cars, industries that pollutes the air with Carbon Dioxide and farmers in the third world that pollutes the air with methane gas. Both Carbon Dioxide and Methane are Greenhouse gases. Since the late 19th century, we have experienced a rise in average global temperatures approximated between 0.6C and 0.2C.

CAUSES

1. Carbon Dioxide from Power Plants
   About 40% of carbon dioxide emissions stem from the burning of fossil fuels for the purpose of electricity generation. Coal accounts for 93 percent of the emissions from the electric utility industry. Coal emits around 1.7 times as much carbon per unit of energy when burned as does natural gas and 1.25 times as much as oil. Natural gas gives off 50% of the carbon dioxide, the principal greenhouse gas, released by coal and 25% less carbon dioxide than oil, for the same amount of energy produced. Coal contains about 80 percent more carbon per unit of energy than gas does, and oil contains about 40 percent more. For the household, a metric ton of carbon equals about 10,000 miles of driving at 25 miles per gallon of gas or about one year of home heating using a natural gas-fired furnace or about four months of electricity from coal-fired generation.
2. Carbon Dioxide from Airplanes
   Aviation causes 3.5 percent of global warming, and that the figure could rise to 15 percent by 2050.
3. Carbon Dioxide from Buildings
   Buildings structure account for about 12% of carbon dioxide emissions.
4. Methane
   While carbon dioxide is the principal greenhouse gas, methane is second most important. Methane is more than 20 times as effective as CO2 at trapping heat in the atmosphere. Levels of atmospheric methane have risen 145% in the last 100 years. Methane is derived from sources such as rice paddies, bovine flatulence, bacteria in bogs and fossil fuel production. Most of the world's rice is grown on flooded fields. When fields are flooded, anaerobic conditions develop and the organic matter in the soil decomposes, releasing CH4 to the atmosphere, primarily through the rice plants.
5. Deforestation
   After carbon emissions caused by humans, deforestation is the second principle cause of atmospheric carbon dioxide. Deforestation is responsible for 25% of all carbon emissions entering the atmosphere, by the burning and cutting of about 34 million acres of trees each year. We are losing millions of acres of rainforests each year, the equivalent in area to the size of Italy. The destroying of tropical forests alone is throwing hundreds of millions of tons of carbon dioxide into the atmosphere each year. We are also losing temperate forests. The temperate forests of the world account for an absorption rate of 2 billion tons of carbon annually. In the temperate forests of Siberia alone, the earth is losing 10 million acres per year.

EFFECTS

The predicted effects of global warming on the environment and for human life are numerous and varied. It is generally difficult to attribute specific natural phenomena to long-term causes, but some effects of recent climate change may already be occurring. Rising sea levels, glacier retreat, and altered patterns of agriculture are cited as direct consequences, but predictions for secondary and regional effects include extreme weather events, an expansion of tropical diseases, and drastic economic impact. Concerns have led to political activism advocating proposals to mitigate, eliminate, or adapt to it.

1. Effects on weather

   Increasing temperature is likely to lead to increasing precipitation but the effects on storms are less clear. Extra tropical storms partly depend on the temperature gradient, which is predicted to weaken in the northern hemisphere as the polar region warms more than the rest of the hemisphere. Storm strength leading to extreme weather is increasing, such as the power dissipation index of hurricane intensity. Catastrophes resulting from extreme weather are exacerbated by increasing population densities. A substantially higher risk of extreme weather does not necessarily mean a noticeably greater risk of slightly-above-average weather. However, the evidence is clear that severe weather and moderate rainfall are also increasing.

2. Economic Effect

   Many estimates of aggregate net economic costs of damages from climate change across the globe, the social cost of carbon (SCC), expressed in terms of future net benefits and costs that are discounted to the present, are now available. Peer-reviewed estimates of the SCC for 2015 have an average value of US$43 per tonne of carbon (tC) (i.e., US$12 per tonne of carbon dioxide) but the range around this mean is large. For example, in a survey of 100 estimates, the values ran from US$-10 per tonne of carbon (US$-3 per tonne of carbon dioxide) up to US$350/tC (US$95 per tonne of carbon dioxide.) World Bank report states that climate change could affect growth which could be cut by one-fifth unless drastic action is taken. It has warned that one percent of global GDP is required to be invested in order to mitigate the effects of climate change, and that failure to do so could risk a recession worth up to twenty percent of global GDP. WB's report suggests that climate change threatens to be the greatest and widest-ranging market failure ever seen. The report has had significant political effects: Australia reported two days after the report was released that they would allott AU$60 million to projects to help cut greenhouse gas emissions.

3. Effects on agriculture

   For some time it was hoped that a positive effect of global warming would be increased agricultural yields, because of the role of carbon dioxide in photosynthesis, especially in preventing photorespiration, which is responsible for significant destruction of several crops. In Iceland, rising temperatures have made possible the widespread sowing of barley, which was untenable twenty years ago. Some of the warming is due to a local (possibly temporary) effect via ocean currents from the Caribbean, which has also affected fish stocks. While local benefits may be felt in some regions (such as Siberia), recent evidence is that global yields will be negatively affected. "Rising atmospheric temperatures, longer droughts and side-effects of both, such as higher levels of ground-level ozone gas, are likely to bring about a substantial reduction in crop yields in the coming decades, large-scale experiments have shown". Moreover, the region likely to be worst affected is Africa, both because its geography makes it particularly vulnerable, and because seventy per cent of the population rely on rain-fed agriculture for their livelihoods. Tanzania's official report on climate change suggests that the areas that usually get two rainfalls in the year will probably get more, and those that get only one rainy season will get far less. The net result is expected to be that 33% less maize—the country's staple crop—will be grown.

4. Effects on Health

   The most direct effect of climate change would be the impacts of hotter temperatures themselves. Extreme high temperatures increase the number of people who die on a given day for many reasons: people with heart problems are vulnerable because one's cardiovascular system must work harder to keep the body cool during hot weather, heat exhaustion, and some respiratory problems increase. Global warming could mean more cardiovascular diseases; doctors warn higher air temperature also increase the concentration of ozone at ground level. In the lower atmosphere, ozone is a harmful pollutant. It damages lung tissues and causes problems for people with asthma and other lung diseases. Rising temperatures have two opposing direct effects on mortality: higher temperatures in winter reduce deaths from cold; higher temperatures in summer increase heat-related deaths. The distribution of these changes obviously differs. Global warming is expected to extend the favorable zones for vectors conveying infectious disease such as dengue fever and malaria. In poorer countries, this may simply lead to higher incidence of such diseases. In richer countries, where such diseases have been eliminated or kept in check by vaccination, draining swamps and using pesticides, the consequences may be felt more in economic than health terms. The World Health Organization (WHO) says global warming could lead to a major increase in insect-borne diseases in Britain and Europe, as northern Europe becomes warmer, ticks - which carry encephalitis and lyme disease - and sand flies - which carry visceral leishmaniasis - are likely to move in.

   The broad agreement among climate scientists that global temperatures will continue to increase has led nations, states, corporations and individuals to implement actions to try to curtail global warming or adjust to it. Many environmental groups encourage action against global warming, often by the consumer, but also by community and regional organizations. There has also been business action on climate change, including efforts at increased energy efficiency and (still limited) moves to alternative fuels. One important innovation has been the development of greenhouse gas emissions trading through which companies, in conjunction with government, agree to cap their emissions or to purchase credits from those below their allowances.

By

Romila Chitturi

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