Global Warming Issues - Essay Example

Global Warming There can be no clearer illustration of the need for human beings to act globally than the issues raised by the impact of human activity on our atmosphere. That we all share the same planet came to our attention in a particularly pressing way in the 1970's when scientists discovered that the use of Chlorofluorocarbons (CFC) threatens the ozone layer shielding the surface of our planet from the full force of the sun's ultraviolet radiation. After signing Montreal Protocol in 1985 and getting rid of CFC's has turned out to be just the curtain raiser: the main event is climate change or global warming. Without belittling the pioneering achievement of those who brought about the Montreal Protocol, the problem was not so difficult, for CFC's can be replaced in all their uses at relatively little cost, and the solution to the problem is simply to stop producing them. Climate change is a very different matter. The greenhouse effect is a natural atmospheric process caused by the presence of certain gases in the atmospheric process caused by the presence of certain gases in the atmosphere that prevent the infrared radiation emitted from escaping from the earth's surface to space. As a result, the temperature of the atmosphere increases, until a new equilibrium between in going solar radiation and out going infrared radiation is reached. The process is analogous to the way in which a greenhouse increases the temperature inside. The gases that absorb out going infrared radiation are called green house gases (GHG's). Some GHG's are that exists naturally: carbon dioxide (Co2) and small quantities of Methane (CH4). Thus the greenhouse effect has always been with us. In its absence, the earth's mean temperature would be 30C lower than it is, which would mean the end of life on the planet, an ice covered places. The progressive gradual rise of the earth's average surface temperature, thought to be caused in part by increased concentrations of GHG's in the atmosphere, is called global warming, which is commonly described as climate change, although global warming is only one of the changes that affect the global climate. Our main concern is that since the industrial revolution there has been a considerable increase in emissions of GHG's resulting in considerable increase in their concentrations in earth's atmosphere. The natural balance of the greenhouse effect is currently lost. One to this serious nature of climate change a widely recognized organization IPCC was setup in 1988. The scientific evidence that human activities are changing the climate of our planet has been studied by a working group of the intergovernmental panel on climate change, or IPCC, an international scientific body intended to provide policymakers with an authoritative view of climate change and its causes and affect. The IPCC includes three working groups: (i) Working group 1 (WG1) assesses the scientific aspects of the climate system and climate change (ii) working group 2 (WG2) assesses the vulnerability of Socio-economic and natural system of climate changes and options for adopting it; (iii) working groups 3 (WG3) assesses the options for limiting GHG emissions and otherwise mitigating climate change. Every few years, each working group publishes an assessment reports. The fourth of these reports (called AR4) was published this year. Working group 1 has already its part of AR4 (IPCC, 2007 a). Some of their findings are: Global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities since 1750 and non for exceed pre-industrial value. The global increases in carbon dioxide concentration are primarily to fossil fuel use and land-use change, while those of Methane and Nitrous oxide are primarily due to agriculture. (ii) Warming of climate system is unequivocal, as is no evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global mean sea level. (iii) At continental, regional and ocean basin scales numerous long-term changes in climate have been observed. These include changes in arctic temperatures and ice, widespread changes in precipitation amounts, ocean salinity, wind patterns and aspects of extreme weather including droughts, heavy precipitations, heat waves and the intensity of tropical cyclones. (iv) Paleoclimate information supports the interpretations that the warmth of the last half-century is unusual in at least the previous 1300 years. The last time the Polar Regions significantly warmer than present for an extended period (about 125000 years ago), reductions in polar ice volume led to 4 to 6 meters rise in sea level. (v) Most of the observed increase in globally averaged temperature since the mid 20th century is very likely due to the observed increase in anthropogenic GHG's concentrations----- Discernible human influence non extend to other aspects of climate, including ocean warming, continental average temperatures, temperature extremes and wind patterns. (vi) For the next 2 decades a warming of about 0.2C per decade is projected for a range of emission scenarios. Even if the concentrations of all GHG's and aerosols had been kept constant at year 2000 levels a further warming of about 0.1C per decade would be expected. (vii) Anthropogenic warming and sea level rise would continue for centuries due to the timescales associated with climate processes and feedbacks, even if GHG concentrations were to be stabilized. Changes, which earlier took millions of years, are now taking place in decades without allowing ecosystems sufficient times to adapt. As a result many species of flora and fauna could become extinct. Climate change threatens the basic elements of life for people around the world. The basic damages from the climate change will accelerate, as the world gets warmer. Such changes could include-sudden shifts in regional weather patterns. Moreover sea level rise from melting or collapse of ice sheets would eventually threaten land which today is home to 1 in every 20 people. The third assessment report of IPCC in 2001 finds out that our planet has shown clear signs of warming over the past century. In fact 9 of the 10 hottest years during 90's, the temperatures are now rising at three times the rate of the early 1900's ("This year was the second hottest, confirming a trend, UN says," New York Times, 19th December 2001, p. A5.). Sea levels have risen by between 10 and 20 centimeters (4 to 8 inches) over the past century. Since 1960's snow and ice cover has decreased by about 10 percent and mountain glaciers are in retreat everywhere except near the poles. In the past three decades the El Nino effect in the southern hemisphere has become more intense, causing greater variation in rainfall. Paralleling these changes in an unprecedented increase in concentration of carbon dioxide, Methane and nitrous oxide in the atmosphere, produced by human activities such as burning fossil fuels, the clearing of vegetation and cattle and rice production. Not for at least 4,20,000 years have there been so much carbon dioxide and Methane in the atmosphere. The third assessment report estimates that between 1990 and 2100, average global temperatures will rise by at least 1.4 C (2.5 F) and perhaps by as much as 5.8 C (10.4 F) (Houghton, J. H. et al. eds. 2001). Although these average figures may seen quite small-whether tomorrow is going to be 20C or 22C is not such a big deal-even a 1C rise in average temperatures would be greater than any change that has occurred in a single century for the past 10,000 years, Moreover, some regional changes will be more extreme and much more difficult to predict. Northern landmasses especially North America and Central Asia will warm more than the oceans or coastal regions. There will also be greater year-to-year fluctuations than at present which means that droughts and floods will increase. It is possible that the changes could be enough to reach critical tipping points at which the weather systems alter or the directions of the major ocean currents, such as Gulf Stream, change. As a consequence of these climate changes, the following risk may arise: As oceans become warmer, hurricanes and tropical storms that are now largely confined to the tropics will move further from the equator, hitting large urban areas that have not been built to cope with them. Tropical diseases will become more widespread. Food production will increase in some regions, especially in the high northern latitudes, and fall in others, including sub- Saharan. Africa, sea levels will rise by between 9 and 88 cm. Greenhouse warming is a destabilizing factor that makes abrupt climate change more probable. A 2002 report by the U.S. national academy of sciences (NAS) said, available evidence suggests that abrupt climate changes are not only possible but also likely in future, potentially with large impacts on ecosystems and societies (Abrupt climate change: inevitable surprises, U. S. national academy of sciences, national, Research council committee on abrupt climate change, National academy Press, 2002). Scientists has so far identified ocean conveyor / currents are one of the fundamental factors governing our earth's climate. The ocean also plays an important role in controlling earth's climate. The EL Nino phenomenon is a hint of how oceanic changes can dramatically affect where and how much precipitation falls throughout the planet. Oceanic heat pump is an important mechanism for reducing equator to pole temperature different. It moderates earth's climate, particularly in the North Atlantic region. The North Atlantic conveyor warms the North Atlantic regions by as much as 5C and significantly tempers average winter temperature. But the part records show that the current has slowed and shut down which curtailed heat delivery to the North Atlantic and caused substantial cooling throughout the region. One earth scientist has called the conveyor / current the Achilles heel of our climate system (Broecker, W.S., 1997). It has been-indicated by different computer models that North Atlantic region would cool 3C to 5C if current circulation were totally disrupted. It would produce winters twice as cold as the worst winters on records in the eastern United States in the past century. In an important paper published in 2002 in Nature, Oceanographers monitoring and analyzing conditions in the North Atlantic concluded that the North Atlantic has been freshening dramatically continuously for the past 40 years but especially in the last decade (Dickson, B. et al., 2002). Though it has not been established but global warming may be one of the important factor which had affected the precipitation in North Atlantic. Now it has been established that global warming affects the hydrological cycle because a warmer atmosphere carries more water. Studying the past climate change has the potential of understanding of future climate system. A bad winter or severe winter may cause inconvenience to societies at large but the persistent winters lasting decades can convert agriculturist land unfarmable. Thermohaline shutdown could cool down to 3C to 5C and can cause drought in many parts of the world. These climate changes are critical to consider economic and political ramifications. The region most affected by this shutdown the countries bordering. North Atlantic is also one of the most developed. Another important adverse impact of global warming has been visible in the form of higher sea level. It may be caused due to thermal expansion and meltdown of glaciers and ice sheets. It is difficult for the scientists to be more precise with sea level projections because uncertainly in GHG's concentrations in the future, climate sensitivity, ocean heat exchange and response of ice sheets in Greenland and Antarctica. As the third assessment report 2001 of IPCC estimated average 50 cm. increase in sea-level by 2100, can washed away significant portion of islands and directly affect the drinking water supply. The people living in the low level coastal areas especially in southern Asia would be badly affected by sea level rise. So with the small level of sea level rise can destroy whole nation, culture etc. Recent studies show that Greenland ice sheet will begin to melt if the temperature there raises 3C. The complete melting of Greenland would raise sea levels by 7 meters but even a partial melting could raise sea level by 1 meter and have devastating impact on low-lying island countries, densely populated Nile delta, countries like Bangladesh and also on the Gulf coast and eastern seaboard of the United States. Due to involvement of long-time constants sea level is likely to rise even after achieving the significant limitations in emission of Co2 and other GHG's. However, these global changes are only one factor in what determines sea level change at any particular coastal location. For example, along the Mid-Atlantic coast, where land levels as subsiding, relative sea level rise will be somewhat greater; conversely, in New England, where land levels are rising relative sea level rise will be somewhat less. Not surprisingly, an increased rate of global sea level rise is unlikely to have the most dramatic impacts in regions where subsidence and erosion problems already exist. Estuaries, wetlands and shorelines are especially vulnerable. Impact on the fixed structures will intensify, even in the absence of an increase in storminess. Even a small rise in sea level can produce a large inland shift of the shoreline. The rise will be particularly important if the frequency or intensity of storm surges or hurricanes increases. Costal erosion increases the threat to costal development, transportation infrastructure, tourism freshwater aquifers, fisheries and costal ecosystem. Coastal cities and towns, especially those in storm-prone regions are particularly vulnerable. Intensive residential and commercial development in these regions is placing more and more lives and property at risk. Now it has been evident that global warming causes the climatic change and if the GHG's emission could be stabilized by the end of the 21st century, sea level rise from ocean thermal expansion may only have reached half its eventual level by the year 2500. To minimize the impact of climate change we need to start changing our habits as soon as possible. The longer we delay, the less effective our actions will be so what's almost certain is that if nothing done about global warming, it will happen sooner rather than later. References: 1. IPCC (2007A): Climate Change 2007: The Physical Science Basis: Summary For Policy Makers, Contribution Of Working Group I To The Fourth Assessment Report Of The Intergovernmental Panel For Climate Change available from Accessed on 14th December 2007. 2. "This year was the second hottest, confirming a trend, UN says," New York Times, 19th December 2001, p. A5. 3. Houghton, J. H. et al. Ed. (2001), Climate change 2001:The scientific basis: contribution of working group I to the third assessment report of the IPCC, UN Environment programme and IPCC, Cambridge university press, Cambridge. 4. Abrupt climate change: inevitable surprises, U. S. national academy of sciences, (2002), National Research council committee on abrupt climate change, National academy Press. 5. Broecker, W.S (1997), Thermohaline circulation the Achilles heel of our climate system: will man-made CO2 upset the current balance In Science, vol. 278, Nov-28, Lamont-Doherty Earth observatory, Columbia university. 6. Dickson, B., yashayaev, I., Meincke, J., Turrell, B., Dye, S. and Hoffort, J. (2002), Rapid Freshening of the deep North Atlantic ocean over the past four decades in Nature vol. 416, April 25, by Center for Environment, Fisheries and aquacultures Science, Lowestoft, UK. Read More