Global warming

What is global warming

Global warming is a phenomenon of the increase in the average temperature on the surface of the Earth. It concerns our whole planet (so it is a global phenomenon): both the atmosphere and surface water. Gradual global warming has been observed since the end of the 19^th century, from then to the beginning of the 21^st century the average temperature on the Earth increased by 0.7^oC. The International Climate Change Team estimates that in the next century the temperature will increase from 1.4 to 5.8 ^oC.

The observed temperature changes and other climate changes (e.g. resulting from shift in climatic zones) induced the international community to measure and observe climate change systematically. It transpired that one of the main reasons of global warming is human activity (the emission of greenhouse gases and progressive degradation of forest areas) which consequently led to the activities whose aim was to limit human influence on the progress of these processes.

The causes of global warming

The escalation of the greenhouse effect is said to be the main cause of global warming. It is caused by the higher concentration of gases which prevent radiation created on the Earth from escaping. Another cause is the change of albedo, the coefficient of sunlight reflection; this phenomenon is the consequence of the degradation of forests which are cut down and burnt.

Admittedly, in the past there were sudden or gradual changes in temperature of the Earth. The example is Ice Age when people had hardly any influence on the environment, however, climate changed. Changes were also observed in our era (alternating colder and warmer periods). There was a little Ice Age whose intensity dated to the first half of the 17^th century. After 1850 there was warming which was also interrupted by cold decades. Such climatic processes were probably the consequence of changeable activity of the Sun and volcanoes as well as transformations in the circulation of oceanic water.

The escalation of the greenhouse effect drew scientists' attention to human activity. Therefore, at the time of omnipresent pollution and careless emission of greenhouse gases, the current climate changes (global warming) are perceived as being the consequence of our activity.

The effects of global warming

Progressive global warming may have catastrophic influence on the life on the Earth. It is true that life has survived drastic climate changes many a time; however every time it was associated with huge changes in the structure of fauna and flora on our planet. Thus being aware of possible changes, we can prevent them to some extent or prepare ourselves for them due to which it will be possible for civilization, people and the majority of living species of plants and animals to survive.

The main consequence of global warming may be a radical change in climatic conditions. The changes which have already been noticed indicate this: the average yearly temperature increased, the water level rose due to glacier melting, climatic zones are shifting. In Europe the seasons do not differ from each other so much: winters are warm with little snowfall, summers are hot, often dry or very wet. For some time extreme weather phenomena have escalated: heat waves (droughts), heavy rain (floods), hurricanes. Huge green areas are threatened owing to climate change - they dry or are flooded with water; species which live there are forced to migrate or they die; mountain glaciers melt which influences the cycle of water in the environment and also poses a threat to local ecosystems, coral reef dies.

Scientists warn that if temperature on the Earth rises to the level exceeding 2 ^oC, there will be a climate catastrophe. If glaciers continue melting, it will enhance the rise in the level of water and its temperature. If permafrost melts, huge number of greenhouse gases will be released to the atmosphere which will also speed up the process of warming, water and forest ecosystems will be threatened with drying or flooding. Due to the rise in the level of water, some islands may vanish from the face of the Earth. Maldives on the Indian Ocean may be completely flooded with water in 30 years.

In the long term it is estimated that melting of glaciers on Greenland and Antarctica may lead to the rise in the level of oceans and seas even by 7 metres, which will disturb water and atmospheric circulation. The Gulf Stream - a warm ocean current which warms Europe - will be threatened. If it stops or changes its direction, climate may cool drastically or it may have other unpredictable effects.

Global warming - prevention

While we are not able to prevent from natural processes, besides, it would defeat the purpose of environmental protection and ecology, we can reduce the influence of human on the environment by using resources more sensibly and eliminating the emission of harmful substances, which have destructive impact on the whole environment, to the atmosphere, water and soil. One of the reasons of global warming is undoubtedly greenhouse effect.

The fourth report of International Climate Change Team, published at the beginning of 2007, states that climate changes are probably caused by human activity in 90 per cent.

In this situation the most effective way of preventing progressive global warming will be first and foremost restrictions on the emission of greenhouse gases which are responsible for trapping thermal radiation in the atmosphere of our planer and stopping the destruction of forest areas which regulate the amount of oxygen and carbon dioxide in the atmosphere. International activities include the introduction of global and local restrictions on the emission of greenhouse gases which are created in the industrial and transport processes by using fuels. It is about reducing the emission of carbon dioxide, methane, nitric oxide, HFC and PFC - organic chemical compounds used in industry.

How can it be achieved? First of all we have to focus on using resources economically, using appropriate filters as protection, promoting alternative methods of acquiring energy (solar and wind power) and of course limiting forest thinning.

Global warming and climate changes

Global warming is undoubtedly one of the main causes of progressive climate changes. The increase in average temperature, rise in the level of water, disturbance in atmospheric and water circulation - all these phenomena have impact on the processes which influence climate on the Earth.

The main climate changes connected with global warming include increase in the average yearly temperature, gradual disappearance of seasons in the zones of a moderate climate - winters are warmer and warmer and summers are hotter. What is more, the difference between temperature at night and temperature during the day decreases, average night temperature rises faster than temperature during the day. The circulation of water is disturbed which is the reason for changes in the amount of rainfall: in some areas it increases (the northern hemisphere) and in other the amount of rainfall decreases (Africa), due to which the Earth's dry and wet areas are shifting. Furthermore these phenomena cause the escalation of extreme weather phenomena such as floods or droughts, devastating winds and hurricanes.

Regular and predictable climatic phenomena change so drastically that their escalation and potential influence on the environment are more and more difficult to be predicted. For instance: El Nino - which appears once every five years on average, now is much more violent and sudden.

Of course all these changes have impact on the functioning of all living organisms: if a species cannot adjust, it gradually dies out or migrates to new territories.

The role of greenhouse gases in global warming

Despite incessant arguments over people's influence on the global warming, International Climate Change Team assessed that we are responsible for this phenomenon in 90%. Anthropogenic emission of greenhouse gases has the greatest influence here.

These gases include mainly carbon dioxide, methane, nitrous oxide and so-called tropospheric ozone which is ozone which remains in the lower layers of the atmosphere.

The phenomenon of the influence of greenhouse gases on climate warming is called radiative forcing and it is measured in watts per square metre. The gases which have the highest coefficient of radiative forcing, out of gases emitted by human, are carbon dioxide (1.46) and methane (0.48).

The research which was conducted shows that the concentration of carbon dioxide in the air is the highest from about 420 thousand years (it is estimated that it is even twenty million). Since 1750 the concentration of carbon dioxide has increased by about 31% whereas the concentration of methane has risen by 151% (since 1750 as well). The content of nitrous oxide has increased by 17% and of tropospheric ozone by 35%.

However, the most significant greenhouse gas which influences comprehensively climatic phenomena on the Earth is water vapour. First of all, water vapour in the air is responsible for accumulating heat in the atmosphere and on the surface of the Earth and, secondly, it builds clouds. Clouds, on the other hand, influence climate in two different ways: they warm or cool it. It depends on their thickness, location and height. Nevertheless, the influence of cloudiness and all factors which cloudiness depends on and the effects caused by cloudiness are not entirely defined - therefore, as a matter of fact, the influence of cloudiness and the main greenhouse gas on global warming is unpredictable.