Which is the global warming origin?

The greenhouse effect is caused by gases that have taken place along the history of the planet and they take place at the moment as a result of the complex activity geochemistry and biochemistry that it characterizes the Earth. 

The atmosphere of our world from its first times so far has experienced remarkable variations in its composition. At the moment it contains, among other gases, dioxide of carbon, methane and nitrogen oxides which are the responsible ones  main of the grenhouse effect. As a result of the intense, and sometimes irrational, man's activity mainly starting from the Industrial Revolution one comes increasing the content of these four gases in the atmosphere and  has even accumulated a significant presence of others as a result of certain developments of the technique. The certain thing is that such increments are being reflected in an escalation of the natural greenhouse effect

In the past fifty years the emissions rushed to the atmosphere of dioxide of carbon, nitrogen oxides, and methane, have risen in arrow, and a new type of chemical substance, the fluorclorocarbonos, CFC, have been introduced as refrigerants, and propellers of aerosols, showing next to their chemical inertia that made them seem inoffensive, a destructive power of the stratospheric ozone layer and a high capacity to catch the heat. A molecule of CFC is an absorbent power of the infrared radiations between 12 000 and 16 000 times   that the one presented by a molecule of the carbon dioxide.

This graph shows the relative contribution from each gas to the greenhouse effect in agreement  with its heating capacity of absorption and the relative abundance in that  they were presented at the end of last century. A notable difference is observed in the data considered by different sources.
 

This difference  is explained for the relative uncertainty of the quantitative estimates about the concentrations of these substances in the atmospheric layers. Anyway, it is pointed out as the main responsible to the dioxide of carbon with a specific weight that moves in the interval of 55% - 75%. The biggest discrepancy that explains the previous difference, is appreciated in the estimate of the relative contribution of the halocarbonos. Some sources assign him the second place with 24% of the total effect while others indicate that in accordance with the reduction in the production of CFC of the last decade its contribution to the geenhouse effect doesn't go up to 5%. All the reports coincide in attributing 15% approximately from the total effect to the methane. And finally the significant contribution appears from 5% to the nitrogen oxides.       

Carbon dioxide enters in the natural carbon cycle, the animals emit it to the atmosphere in the breathing, the plants assimilate it in its photo-syntheses. The deforestation that has suffered the planet comes affecting this cycle, contributing to the accumulation of the carbon dioxide in the atmosphere.

Burning of the fossil fuels in the power plants and for the self-driven transport it has shot the launching of emissions of CO₂  at the atmosphere.  

The nitrogen oxide is a colateral product in the production of the nylon, and it is also emitted by the fertilizers used in the agriculture. 

The methane is emitted in the mines of coal, in the locations of the natural gas as well as in its distribution. It also takes place in the deposits of residual and a fifth part of the whole methane generated by the human activity comes from the microbial decomposition of the organic material associated with the rice production. 

The graph of up  reveals clearly that it is the CO₂ the greenhouse gas with more responsibility in the anthropogenic heating global that suffers the planet. Unfortunately, according with the square of unequal development and irrational consumption that it characterizes to our contemporary society you can appreciate that "the contributions" to this global warming of the planet it is very different according to the geo-economic area.

 

The figure reveals as the industrialized countries present the absolute indexes and higher per-inhabitant index of CO₂emission. The absolute leadership has it the United States of America with an equivalent energy consumption to the emission of some 20 tons of C0₂ annually. In terms of efficiency it is considered the Western Europe as "an efficient consumer", eight tons for inhabitant per year.
 

 Scenario A 
Quantity of the emissions of CO₂ if each region consumed with the index per capita of Europe Occidental.  

Scenario B  
Quantity of the emissions of CO₂ if each region consumed with the index per capita of China or Latin America, something more than 2 tons per year.
      
If all in this planetary ship had an index of  emission equivalent to the efficient Europe our atmosphere would receive the equivalent one to 1,7 times the quantity of CO₂ that it   received at the end of last century. And if it took place the unthinkable reversion that we all emitted with an equivalent per capita equal to that of our Latin America, then we would be reducing the emission from the CO₂ to 40,8% of that rushed in the 2000.

Reference:

Union of Concerned Scientists (2005): Global warming science and global warming solutions.

http://www.ucsusa.org/global_warming/science/science-of-global-warming.html