Global Climate Change

At present, the Earth appears to be facing rapid warming, which, most scientists believe, results, at least in part, from human activities. The chief cause of climate change is thought to be the burning of fossil fuels, such as coal, oil and natural gas, which release carbon dioxide into the atmosphere and other substances known as greenhouse gases.

What is Global climate change?

Global climate change is a change in the long-term weather patterns that characterize the regions of the world. The term weather refers to the short-term changes in temperature, wind, or precipitation of a region.

Causes of climate change

The input of carbon dioxide (CO2) into the atmosphere through industrial activities has been suggested to be associated with warming near the surface as additional longwave radiation emitted at the surface is absorbed by the CO2 and radiated back toward the surface. There is concern that by the year 2100 the enhanced CO2 level resulting from the industrial activity will increase the average global temperature by as much as 5-C, with the greatest impact at high altitudes. The climate varies and will always vary for natural reasons.

However, human activities are significantly increasing the concentrations of some gases in the atmosphere, such as greenhouse gases (mainly CO2), which tend to warm the earth surface, and anthropogenic aerosols, which mostly tend to warm it. The causes of the climate changes have been attributed to a variety of mechanisms, including increased volcanic emissions that have been associated with the blocking of sunlight and the resultant warmth at the surface.

Scientific group issues climate change warning

The average surface temperature of the Earth is about 15-C (59-F). Over the last century, this average has risen by about 0.6 Celsius degree (1 Fahrenheit degree). Scientists predict further warning of 1.4 to 5.8 Celsius degrees (2.5 to 10.4).

Polar ice caps and glaciers as well as warm the oceans, all of which will expand ocean volume and raise sea level by an estimated 9 to 100 cm (4 to 40 inches). flooding some coastal regions and even entire islands. Some regions in w climates will receive more rainfall than before, but soils will dry out faster between storms. Fahrenheit degrees) by the year 2100. This temperature rise is expected to melt.

Impact of human activities on climate

Three distinct atmospheric problems have been debated intensely since about the mid-1970s, though two of them are quite old issues: the possible reduction of stratospheric ozone from chemical emissions; the generation of acid rain; and climatic change stemming from the greenhouse effect. What these three problems have in common is quite simple:

1. they all are complex and punctuated by large uncertainties,

2. could be long-lasting,

3. transcend state and even national boundaries,

4. may be difficult to reverse,

5. are inadvertent by-products of widely supported economic activities, and

6. may require sub- substantial investments of present resources to hedge against the prospect of large future environmental changes.

Ozone depletion

The importance of the stratospheric ozone layer in shielding the Earth's surface from the harmful effects of solar ultraviolet radiation has been recognized for several decades. It was not until the early 1970s, however, that scientists began actually to grapple with the fact that even relatively small decreases in the stratospheric ozone concentration can have a serious impact on human health; an increased incidence of skin cancer.

Acid rain

Scientific studies have shown that the process that results in the formation of acid rain generally begins with the discharge of sulfur dioxide and nitrogen oxide into the atmosphere. These waste gases are released by the combustion of fossil fuels by automobiles, power plants, and melting and refining facilities. They also are emitted by some biological processes. The consequent acidification of surface and subsurface waters is widely believed to have a detrimental effect on the ecology of the affected areas. As highly acidic water is toxic to many aquatic organisms, many lakes in these regions are biologically damaged. It has also been found that acid precipitation is harmful to trees and other forms of vegetation, causing foliar injury and reduction in growth.

Unfortunately, there is no period in the Earth history that investigators can examine when carbon dioxide concentrations in the atmosphere were, say, Global climatic response what they are today and whose climatic conditions are known with a high degree of certainty. For this reason, investigators cannot directly verify their quantitative predictions of greenhouse warming on the basis of historical analogues. Instead, they must base their estimates on climatic models. These are not laboratory models, since no laboratory could approach the complexity of the real world.

Regional climatic response

To estimate the importance of climate changes to society, researchers need not, however, study global average temperature so much as the possible regional distribution of evolving patterns of climate change in the future. At present, there is simply no consensus among knowledgeable atmospheric scientists that the regional predictions of state-of-the-art models are reliable. Nevertheless, most experts agree that the following coherent regional features might well occur by about the year 2035: wetter subtropical monsoon rain belts: longer growing seasons in high latitudes; wetter springs in high and middle latitudes; drier midsummer conditions in some mid-latitude areas (a potentially serious agricultural and water supply problem in major grain-producing nations); increased probability of extreme heat waves (with possible health consequences for people and animals in already warm climates); and an increase in sea level by a few tens of centimetres. Considerable uncertainty remains in these regional estimates, even though many plausible scenarios have been investigated.

Greenhouse effect

The most long-lasting and potentially least reversible global climate problem is the greenhouse effect. This effect is induced by carbon dioxide, chlorofluorocarbons, methane, and more than a dozen other gases in concentration in the atmosphere. The role played by carbon dioxide is the most significant. The greenhouse problem has received the least policy-oriented attention of the three major issues at hand. There are various reasons for this:

1. The problem is fraught with technical uncertainties.

2. It has perceived "winners" and "losers"-economic and otherwise.

3. No nation acting alone can do much to counteract the CO, buildup in the atmosphere.

4. Dealing with the problem substantively could be expensive and even alter lifestyles.

5. There is no way of proving the validity of the greenhouse theory to everyone's satisfaction except by "performing the experiment" on the real climate system, which would necessarily involve all living things on the Earth.

6. The principal greenhouse gas, CO2, is an inherent by-product of the utilization of a commodity that is most fundamental to the economic viability of the world-fossil- fuel energy.

Greenhouse effect and global warming

The greenhouse effect is à natural occurrence that maintains the Earth's aver- age temperature at approximately 60 degrees Fahrenheit. Without the green- house effect, temperatures on the Earth would be much lower than they are now. and the existence of life on this planet would not be possible. However, too many greenhouse gases in the Earth's atmosphere could result in an increase in mean global temperatures as well as changes in precipitation patterns. The gradual nature of the changes in climate enables the plants, animals, and micro-organisms on earth to evolve and adapt to the new temperatures, precipitation patterns, etc., The real threat of climate change lies in how rapidly the change occurs. For example, over the past 130 years, the 7 mean global temperature appears to have risen 0.6 to 1.2 degrees Fahrenhcit (0.3 to 0.7 degree Celsius). Further evidence suggests that future increases in mean global temperature may occur at a rate of 0.4 degree Fahrenheit (0.2 degree Celsius) each decade.

Consequences of climate change

Regional changes in climate particularly increase in temperature, have already affected some physical and biological systems. Both natural and human systems are vulnerable to climate change because of their limited adap- tive capacity. This vulnerability varies with geographic location, time, and social, economic and environmental conditions. Some extreme weather events and the damage, hardship and death, they cause, are projected to increase with global warming. There is also a potential for large-scale and possibly irreversible impacts which pose risks that have yet to be reliably quantified; their likelihood is probably very low but is expected to increase with the rate, magnitude, and dura- tion of climate change.

Global climate change could impact agriculture, ecosys- tems, forests, sea level, regional weather, human health, and human economics. Agriculture A major cause of global climate change-increased concentrations of atmos- pheric carbon dioxide (CO2) may actually cause some plants to grow better. A warm globe will probably produce as much food as before, but not neces- sarily in the same places. Southern Canada, for example, may benefit from more rainfall and a longer growing season.

At the same time, the semiarid tropical farmlands in some parts of Africa may become further impoverished. Crops and woodlands may also be afflicted by more insects and plant diseases. Ecosystems Biomes, which are closely related to the temperature and precipitation of a region, may actually change. Since ecosystem evolution is generally a slow process, some elements of an ecosystem might have problems adapting to rapid climate change and may not survive. For example, increased ocean tem- peratures may cause a decline in fisheries.

Sea level

An increase in global warming will likely result in a rise in sea level that could threaten many coastal areas around the world. Experts predict that some parts of Bangladesh may become completely submerged if sea levels rise. In fact, sea-level changes will complicate life in many coastal regions. A 100-. cm (40-in) rise could submerge 6 per cent of The Netherlands, 17.5 per cent of Bangladesh, and most or all of many islands. Erosion of cliffs, beaches, and dunes will increase. Storm surges, in which winds locally pile up water and raise the sea, will become more frequent and damaging. As the sea invades the mouths of rivers, flooding from runoff will also increase upstream. Wealthier countries will spend huge amounts of money to protect their shorelines, while poor countries may simply evacuate low-lying coastal regions. Even a modest rise in sea level will greatly change coastal ecosystems. A 50- cm (20-in) rise will submerge about half of the present coastal wetlands of the United States.

Water availability Increases in temperature and a decrease in precipitation may result in increased pressure from people on the groundwater supply. Weather A warmer atmosphere may create more storms and more extreme weather events due to the increased amount of energy present in the ecosystem.

Economic, social, and political effects

Estimating the distribution of economic winners and losers gives a scenario of climate change, involves more than simply looking at the total dollars lost and gained. and in this way, it is possible to make credible calculations. It also requires looking at such important equity questions as who wins and who loses and how the losers might be compensated and the winners taxed. Animals and plants Animals and plants will find it difficult to escape from or adjust to the effects of warming because humans occupy so much land.

Under global warming, animals will tend to migrate toward the poles and up mountainsides toward higher elevations, and plants will shift their ranges, seeking new areas as old habitats grow too warm. Human health In a warmer world, scientists predict that more people will get sick or die from heat stress due to hotter days than to warmer nights. Diseases now found in the tropics, transmitted by mosquitoes and other animal hosts, will widen their range as these animal hosts move into regions formerly too cold for heHN: Other tropical diseases may spread similarly, including dengue fever, yellow fever, and encephalitis. Scientists also predict the rising incidence of allergies and respiratory diseases as warmer air grows more charged with pollutants, more spores, and pollens.

Efforts to control global climate change

The summit on global warming in Kyoto, Japan, which included representatives from the United States, the European Union (EU), and many developing nations, reached an agreement for reducing emissions of gases that many scientists believe may lead to global warming.

National and local programs

The developed countries are all working to reduce greenhouse emissions. Several European countries impose heavy taxes on energy usage, designed partly to curb such emissions. Norway taxes industries according to the amount of carbon dioxide they emit. In the Netherlands, the government and industry have negotiated agreements aimed at increasing energy efficiency, promoting alternative energy sources, and cutting down greenhouse gas output. International agreements International cooperation is required for the successful reduction of greenhouse gases.

In 1992 at the Earth Summit in Rio de Janeiro, Brazil, 150 countries pledged to confront the problem of greenhouse gases and agreed to meet again to translate these good intentions into a binding treaty. In 1997 in Japan, 160 nations drafted a much stronger agreement known as the Kyoto Protocol. This treaty, which has not yet been implemented, calls for the 38 industrialized countries that now release the most greenhouse gases to cut their emissions to below 5 per cent from 1990. The Kyoto Protocol will not be binding until nations accounting for 55 per cent of 1990 greenhouse gas emissions have ratified it.

Most countries are waiting for ratification by the United States, at present the source of one-fifth of greenhouse gas emissions. If Kyoto Protocol are enforced immediately, it would only slightly slow the buildup of greenhouse gases in the atmosphere., Much stronger action would be required later, particularly because the developing nations exempted from the Kyoto rules are expected to produce half the world's greenhouse gases by 2035. There is new and stronger evidence that most of the warming observed during the last 50 years is attributable to human activities. Scientists are predicting.