CLIMATE CHANGE AT GLOBAL LEVEL. INDEX. The first studies : climate changes Albedo Volcanoes and volcanic eruptions Ocean currents and C O 2 Change in temperature and greenhouse gases over time Permafrost Water vapour and clouds Solar variation Displacement of the tropics.
It is arguedthat the current change of the climate is provocated by carelessactions of people.
The Earthhas the ability to react to this change but in a very long time so, forthisreason, people risk to self-destruct.
Animals are shiftingtheir habitat poleward: climatechangemeansalsochanges in the life ofanimalswhichmake a considerableefforttoadapt, hence the pole shift.
The climatechanges and thisdepends on variousfactors:
The albedo is the ratiobetween the amountofsolarenergyreflectedfrom the Earth-atmosphere system and the total energycominginto the system.
The albedo of the Earth-atmosphereis 0,35.
A completely black surface has an albedo of 0 because it absorbs solar rays.
Therefore a surface without snow or ice absorbs more radiation.
One of the more evidentconsequences is the melting of the ice, that, being white, reflects a very effective radiation, while the water and the soil , being darker, reflects less.
The more ice melts because of the increment in temperature, the more soil and water become widespread, and the greater the absorption of heat by the planet is.
A volcano is a geologic, complicated rocky structure, which is generated in the Earth’s crust by the ascent of the magma formed below or in the Earth’s crust.
A volcanic eruption is the leakage of magma and other gaseous materials in the Earth’s surface from the mantle or the crust.
Typically a volcanic eruption happens either in the main crater of a volcano or in the minor craters of the volcano.
The classification is based on the characteristics of magma and on the type of eruption.
Not all of the carbon dioxide we produce stays in the atmosphere, oceans absorb 1/3 and ¼ of C O2every year.
This gas dissolves in salty water, creating carbonic acid .
Since the concentration of atmospheric C O2, keeps increasing, oceans absorb more and more C O2, thus producing more and more carbonic acid. This acid is changing the chemical balance of the oceans: the process is known as “ocean acidification”.
Thermohaline circulation: this is the global oceanic circulation due to the variation of density of the water masses.
A oceanic current is a mass of sea water in movement with respect to the surrounding water and from which it is different in density, salinity, temperature or colour.
The greenhouse gases present in the atmosphere are about 30 and they can capture heat. The water vapour is the most efficient gas in the control of the air temperature of the Earth’s surface. Greenhouse gases are necessary to trap the energy irradiated by surface of the Earth which, otherwise, would be extremely cold. This process limits the flux of energy going outside.
The results show that the Earth's temperature will increase as the greenhouse gases increase.
The gas considered as the most important for the green house effect is the CO2 issued into the atmosphere from the consumption of fossil fuels for human activities. In addition to carbon dioxide, there are other greenhouse gases whose quantity is increasing.
The datas of the Earth’s athmosphere in the past were obtained from the growth of rings of the trees or by the relationships between the isotopes of various elements in the glaciers of Antarctica and Greenland, and in the corals or in lake sediments. From all these data we obtain the average global temperature in the past, and these data are essential to defeat the "global warming". The reconstruction of past temperatures based on indirect data is a very difficult path.