Global climate change: is it fact or a myth?
The reason of climate change
The earth climate is defined by the interacting processes between the sun, oceans, earth surface and biosphere. The sun is the main moving power for weather and climate. Disproportionate heating of earth surface (stronger than closer to equator) appears to be the main cause of winds and oceanic streams.
Up till now earth climate change was happening in the natural way as the activity results of the following basic factors: change of dimension and position towards each other of continents and oceans, solar activity change, earth orbit’s parameters change, change of the air transparantnes and its structure. Strong climate changes appear to be the result of combined activity of different factors.
Atmosphere transparantnes significantly changes during vulcano eruption. Aerosol emissions to the atmosphere may cause temperature fall in consequence of fast shadowing of earth surface. Shifts in temperature are connected with vulcano activity fluctations, as it can be seen from the acid precipitation in glaciers. In cold periods acid precipitation level rises.
Atmosphere structure change may influence on earth radiation balance and therefore change the climate. The main mechanism of the influence is the greenhouse effect. About 30% of coming solar radiation is reflected away from upper layers of the atmosphere and goes back to the space, but the most part of it, however, passes straight through the atmosphere to warm the earth’s surface. Warmed surface emits infra-red radiation. Some gases which present in the atmosphere structure in small quantities (0,1%) have the ability to detain infra-red radiation. They are called green house gases, and the occurrence itself is known as the greenhouse effect.
Greenhouse gases had been in the atmosphere almost during the whole earth history, their balance was maintained at the expense of evapotranspiration cycle. If there were no greenhouse gases in the atmosphere, weather temperature on the earth surface would be over 30-33 C lower, than it is now. On the pre-industrial level carbon dioxide concentration in the atmosphere was 280 ppm (part per million), it has increased to 30% and became 368 ppm by now.
If natural greenhouse effect maintains the earth atmosphere at the thermal balance condition, which is propitious for existence of plants and animal species, than antropogen increasing of greenhouse gas concentration in the atmosphere infringes natural thermal balance of the planet because of green house effect increasing, and as the result causes global warming.
27-04-2006
Source:
IPCC Third Assessment Report, 2001