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NASA/Goddard Space Flight Center Scientific Visualization Studio

One feature of planet Earth that has allowed the development of life is its distance from the Sun that maintains a stable environment. Despite large differences in temperature between the poles and the equator and seasonal variations, our planet's climate is relatively constant. The average temperature of 15° C maintains much of the water in liquid form. What to us seem extreme maximum (57° C recorded in Libya) and minimum (-82° C recorded in Antarctica) temperatures cannot compare with the extremes in our neighbouring planets: For example, temperatures on our cold neighbour Mars average -63° C to 20° C maximum and reach a minimum of -140° C. On our neighbour Venus, warm temperatures can be up to 480° C, with an average of 460° C.

Despite this stability in temperature, since its origin the Earth’s climate has had fluctuations giving rise to both warm and cold ages.

At first the atmosphere was composed of helium, hydrogen, ammonia and methane. Intense volcanic activity changed its composition with the addition of water vapour, carbon dioxide, and nitrogen. The first photosynthesizing organisms, and later plants, substantially contributed to the alteration of the Earth's atmosphere by increasing the proportion of oxygen. Currently, the composition of the atmosphere is the product of the activities of living organisms and contains nitrogen (78.08%), oxygen (20.95%), water vapour (0.247%), argon (0.93%), carbon dioxide (0.038%) and traces of elements such as hydrogen, helium and other gases.

The current composition of the atmosphere allows the stability of the temperature. The Earth receives energy from the Sun in the form of radiation. 70% of the energy is absorbed, warming the earth, sea and air and 30% is reflected. Water vapour, carbon dioxide, ozone and methane in the atmosphere absorb infrared radiation emitted by the Earth's surface causing the "greenhouse effect".

The increase in deforestation and industrial activities using fossil fuels have increased concentrations of carbon dioxide from pre-industrial levels of 270 parts per million to 375 parts per million (2005). Other gases have also increased as a result of human activities. Climate Change in Mexico

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