Docstoc

Global Warming

Document Sample
Global Warming Powered By Docstoc
					                        !!-- Global Warming: --!!

       !!-- A Deadly Threat for Human Life --!!


    Global warming is one of the major environmental issues facing the world today. Global
warming refers to an average increase in the Earth's temperature, which in turn causes changes in
climate. An increase in the temperature of the Earth’s surface may lead to changes in rainfall
patterns, a rise in sea level, and a wide range of impacts on plants, wildlife, and humans. One
cause for Global Warming is called the Greenhouse Effect. The Greenhouse Effect results from a
four step process. First, sunlight radiates from the sun, through space, to Earth's atmosphere.
Second, the sunlight enters the atmosphere and hits Earth. Some of it turns into heat energy in
the form of infrared light. The heat is absorbed by surrounding air and land, which in turn makes
it warm. Third, infrared rays, which are remitted into the atmosphere, are trapped by greenhouse
gases. Finally, the gas then absorbs the light and is remitted back to the Earth's surface and
warms it even more. Human activities have altered the chemical composition of the atmosphere
through the buildup of greenhouse gases – primarily carbon dioxide, methane, and nitrous oxide.
While on average the globe will get warmer and receive more precipitation; individual regions
will experience different climatic changes, with different consequences for the local
environment. Those changes which are the subject of greatest concern are: a rise in sea level,
climatic changes and more extreme weather events, and a greater potential for heat-related
illnesses and deaths.

        First, an increase in the Earth’s surface temperature is causing mountain glaciers the
world over to recede resulting in a rise in sea levels. According to the Union of Concerned
Scientist of USA (ucsusa) the Arctic ice pack has lost about 40 percent of its thickness over the
past four decades. Global sea level is rising about three times faster over the past 100 years
compared with the previous 3,000 years (ucsusa). Melting of glaciers could raise sea levels and
devastate flat and low-lying coastal regions. Fresh water from glaciers could also disrupt the
churning flow of sea water that normally blunts extreme temperature changes. “The ocean’s ice
cover has thinned by an average of four feet- some 40 percent- since the 1960s, and satellite data
show that the ice’s reach has receded 5 percent. More recently, relatively warm Atlantic water
has pushed 20 percent farther into the Arctic than scientists have ever seen - and that water is 1.6
degree f warmer than it was only a decade or so ago” ( Hodges 19). If the arctic continues to
warm, the consequences could be grave. Some scientists think there’s a chance- remote but
conceivable- that the ocean’s summer ice cover could completely melt at some point in coming
decades. Dave Clark, a marine geologist at the University of Wisconsin says:
The absence of ice in the Arctic would completely change climate pattern for the northern
Hemisphere. In computer modeling if you take off the ice, even the circulation of the ocean
reverses. (Hodges 20)

        Global warming and sea level rising is no longer a debatable argument. In fact the
impacts of global warming are real. For example, Rising sea levels are endangering the tiny
Pacific Island nation of Tuvalu. The leaders of Tuvalu—a tiny island country in the Pacific
Ocean midway between Hawaii and Australia—have conceded defeat in their battle with the
rising sea, announcing that they will abandon their homeland. After being rebuffed by Australia,
the Tuvaluan asked New Zealand to accept its 11,000 citizens (Brown). In addition to island
nations, low-lying coastal countries are also threatened by rising sea level. In 2000 the World
Bank published a map showing that a 1-meter rise in sea level would inundate half of
Bangladesh's riceland. With a rise in sea level of up to 1 meter forecast for this century,
Bangladeshis would be forced to migrate not by the thousands but by the millions( Brown).
Secondly, global warming can cause climate changes and extreme weather events. According to
Union of Concerned Scientist of USA (ucsusa) since the beginning of the 20th century, Earth's
mean surface temperature has increased by about 1.1°F (0.6°C). Warming in the 20th century is
greater than at any time during the past 400 to 600 years (ucsusa). Globally average precipitation
is projected to increase, but both increase and decrease will occur depending on the specific
global region. “Precipitation is projected to increase in both summer and winter over high
latitude regions; in winter over northern mid-latitudes, tropical Africa and Antarctica; and in
summer over south and East Asia. Conversely, precipitation is projected to decrease in winter
over Australia, Central America and southern Africa” (Watson 27). Major climate-driven
changes across five continents, changes that are leaving millions homeless, destitute and in
danger. Global warming can cause more heat waves and droughts, resulting in more and more
conflicts over water resources. Global warming is a major threat for fresh water supplies. In
many parts of the world, the signs of global warming are very dramatic. Journalist and
environmental activist Mark Lynas expressed his experience about impacting of global warming
in Alaska,

        The manager of the hostel where I stayed, a keen hunter, told me how ducks had been
swimming on the river in December (it’s supposed to freeze over in autumn); how bears had
become so confused they didn’t know whether to hibernate or stay awake, and that winter
temperatures, which used to plummet to 40 degrees below zero, now barely touched 25 below.
(Lynas 60)
Finally, rising temperatures and increased precipitation are likely to have detrimental effects on
human health. The result of climate changes could be a greater potential for heat-related illnesses
and deaths, as well as an opportunity for infectious diseases, such as, malaria, encephalitis, and
Ebola to spread into new geographical areas that were previously free from them. Assessing
what global warming will mean for human health, however, is a very hugely complex task,
clouded by uncertainties. The US National academy of sciences conducted a study on global
warming and infectious diseases that was published in April 2001. Among the climate triggered
health threats that the studies spotlight are these: “vector-born infectious diseases-such as
malaria, dengue, schistosomiasis, leishmaniasis and encephalitis- may alter their geographical
ranges and seasonality, spreading into new regions and declining in others. Heat-related deaths
could rise in response to more frequent and more intense heat-waves, particularly in temperate-
zone cities and among the elderly. Cold-related mortality might decline but this reduction might
be offset by the increase in heat-stress mortality. Air pollution in urban areas would likely
increase as air temperatures warm- particularly the concentration of ground-level ozone, which is
damaging to respiratory health. Malnutrition risks, and the diseases that accompany malnutrition,
would rise as agricultural practices adapt to new patterns of temperature, rainfall and soil-
moisture conditions. Warming oceans could promote more frequent toxic algal blooms, increase
the incidence of diarrhea related diseases, and spread the risk of poisonings from fish and
shellfish toxin” (Agnew 71). Population displacement, forced by rising sea levels or extreme
weather or agricultural collapse, would complicate the public health challenge. Large numbers of
refugees moving into already populated areas, crowded together, hungry and perhaps starving,
without shelter or adequate sanitation, is a formula for spreading infectious diseases.
Environmental health expert of WHO (World Health Organization) Dr. Carlos Corvalan says,
We don’t yet know how severe the impacts are going to be or how accurate the predictions of
environmental change are, but the evidence is accumulating, and ecological and human impacts
of global warming will strike hardest at developing nations, particularly the poorest. (Agnew 70)




Conclusion:
        There is much debate about the causes and effects of global warming, but with the benefit
of scientific data, the trends toward a change in the makeup of the atmosphere are clear. Global
Warming is a problem that we must deal with immediately. The changes in precipitation and
temperature patterns, ocean circulations, polar cap coverage, and mountain ice will impact all
peoples of the world. It is important that governments, industries and communities understand
the changes that are occurring and take immediate steps to alter the rate of change where possible
and to prepare for the impacts on populations that will occur with global warming.

				
DOCUMENT INFO
Categories:
Tags:
Stats:
views:4
posted:10/20/2012
language:English
pages:3