Complete information on Anthropogenic Impact on Climate

Man and climate mutually affect each other. Sometimes man attempts to control climate deliberately for his personal well being. But, man is also influencing climate inadvertently through his various social and economic activities, such as rapid urbanization, industrialisation, deforestation, farming activities, damming rivers to create artificial lakes for various uses, etc. Thus, man is in fact capable of influencing climate to a considerable extent and is inadvertently changing the earth’s Albedo and atmospheric composition through his activities.

The most widespread modification of the climate in the recent past has been done through massive conversion of natural vegetation into arable lands and pastures which has affected several important climate parameters, such as Albedo, the Bowen ratio, and surface roughness as well as hydrological properties of the surface.

These alterations have certain implications on energy and water balances of the earth resulting in climatic change. Thus, the artificial production of heat (anthropogenic heat), ozone concentration in atmosphere and contribution of particulate matters in the atmosphere by man, change the atmospheric composition particularly the C0₂, ozone, aerosols content, etc.

which ultimately affect fluctuations in climatic elements. Various processes that cause increase and decrease in Albedo and the Bowen Ratio

Since global ecosystem comprises an interconnected web, if anything disturbed and removed by man is not replaced, we can’t avoid heavy damage to over environment. Man is instrumental in environmental construction or destruction both.

But such disruptions in natural balance by anthropogenic factors are attaining such an alarming dimensions, which might have unpredictable consequences capable of undermining the material basis of mankind’s social and economic development and geopardizing its very existence three most important mechanisms of climatic change are: (i) changes in supply of solar energy, (ii) changes in the transmissivity of the atmosphere for both coming and outgoing radiations; and (iii) changes in land use that alters the radiation balance.

Global temperatures have been rising and are expected to continue at least into the near The Earth is treated by the Sun, and the Earth then heats the air. The Earth receives an enormous amount of solar radiation as the Sun’s rays reach the Earth’s atmosphere in the form “of short-wave radiation.

This radiation passes through the atmosphere where much of it is absorbed as it heats the Earth’s surface. The Earth’s surface, heated by the sun’s energy, re-radiates this heat back into space as long-wave, or infrared radiation.

Some of this energy is absorbed by naturally-occurring trace gases in the atmosphere, including water vapour, carbon dioxide, methane, nitrous oxide, and ozone, and – as a result – the temperature of the atmosphere increases.

These energy-absorbing trace gases are known as the greenhouse gases, and this phenomenon in which the Earth’s atmosphere absorbs solar energy re-radiated from the solid Earth is known as the greenhouse effect.

The issue that we are now facing is that human activity – particularly in the burning of fossil fuels and in the clearing of land – is increasing the overall concentration of greenhouse gases. This additional increase is called the ‘enhanced greenhouse effect,’ but it is also referred to as ‘global warming.’

The greenhouse effect of increasing level of greenhouse gases (GRG) in the atmosphere is popularly known as global warming.

The causes of the global warming phenomenon have been traced to increased atmospheric levels of the so called greenhouse gases, namely, carbon dioxide (C0₂), methane (CH₄), nitrous oxide (N₂0) chlorofluorocarbon (CFCs), and the water vapour (H₂0) which is the largest contributor to greenhouse gases.

The main greenhouse gases differ in the intensity of their heat trapping (or “radioactive and atmospheric lifetimes and thus, in their ability to affect the radioactive balance of the CFCs and nitrous oxide are many times more potent than the same quantity of carbon dioxide methane.

Carbon dioxide emission to the atmosphere is coming principally from the use of fuels. Change in land use (deforestation) is also adding CO, to the atmosphere. Livestock (paddies) and natural wet lands, coal mining, natural gas production, biomass burning main sources of methane.

Several studies indicate, that, direct effect of the heat trapping may double the concentration of CO, in the atmosphere, which can increase the global temperature by about 1-2″C. Over the past century the average global temperatures have increased between 0-3 to 0-6°C. CO, is steadily rising from a pre-industrial concentration of 260 to 270 PPM, to a current level of about 350 PPM. It is due to the great inertia of World’s industrial system and their fossil fuel energy bias.

The US National Research Council (NRC) predicted that a nominally doubled CO, concentration of 600 PPM will likely to be reached by the year 2065.

Thus, if some of these greenhouse gases continue to increase at the present rate the global temperature can rise alarmingly by 1.5°C to 4.5″C in the next 50 years and it will pose a new threat to human life (Table 16.5). Industrial Revolution has released huge quantity of CO, to the atmosphere via burning of fossil fuels such as coal, gas and oil. Methane (CH₄) is another important greenhouse gas.

Nearly 15 years have passed since the first evidence of an increase in concentration of atmospheric CH₄ was reported. Up to the present time, several time series measurements of the trend of atmospheric CH₄ had been carried in various locations of the world. The result indicates that the average temporal increase of CH₄ during the last decade was about 1 per cent per year.

Analysis of ancient air trapped in Polar ice cores revealed that the concentration of atmospheric CH₄had remained almost constant at less than half of the present

Atmospheric CH₄ is produced by a wide variety of natural and anthropogenic processes (Table 16.5). Several investigators have estimated atmospheric methane.

They have considered major sources of CH₄ as enteric fermentation by ruminants, emission from natural wetlands, and cultivated wetland paddy fields, decomposition of Organic wastes in landfills and dumps, termites, biomass burning, coal mining operations, and leakage of natural gas.

However, there are great degrees of uncertainties in the estimated values of individual sources, and in the leading causes of the increasing concentration of atmospheric CH₄“, peat lands which occupy large areas in high latitudes are also a potential source of atmospheric CH₄. Chlorofluorocarbons (CFCS) are other potential greenhouse gases which significantly contribute to the global warming consequently causing modifications in climatic.