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Joan Grimalt

The human influence on the coming climate URL:

Science and technology are without doubt a benefit for all countries. As a matter of fact, they have transformed the human history and the planet itself. And this has occurred rather recently. Humans have inhabited planet Earth for several millions of years. In the past we discovered two activities that have allowed us to transcend our condition of simple ecosystem components: namely, making fire and agriculture. Nevertheless, the most vital invention is much more recent. Around 200 years ago we learned how to obtain work out of heat. This was really the key step  because it freed a lot people from having to depend from manual works. This is the discovery that triggered the industrial revolution.

Having a higher percentage of people devoted to thinking changed the world. In these last 200 years the scientific basis of physics, chemistry and biology were set. From the technological perspective we have the inventions of the steam motor and explosion motors, the development of nuclear energy, and the beginning of space exploration. From the sanitary perspectives, we have obtained vaccines, antibiotics, and surgery has reach a great development. As a consequence of all, we have seen how the average life expectancy has gone from around 40 years, up to an interval around 75-80 years.

All of this has also caused a huge increase of the world population. The average number of humans used to be around 50 millions. The increase was very slight until we reached the industrial revolution that gave way to reaching the 6300 millions of humans we have now. This is a completely novel and unique historical situation, and poses a number of threats that we will have to overcome.

The huge consumption of fossil fuels has produced an important increase in atmospheric CO2. Any kind of combustion produces CO2 in the best possible scenario (in the worst, a mixture of diverse contaminants). Along the last 150 years the concentration of this gas has increased around 100 parts per million due to human activities. This increase is equivalent to what has happened naturally each time our planet has gone from a glacial period to an interglacial period. But on top of this, the current concentration of CO2 (380 parts per million) is still higher that in any concentration observed in interglacial (280 parts per million) or glacial (190 parts per million) period of the Quaternary. The current situation of the planet is totally unexpected from the point of view natural evolution. There is no equivalence of such high CO2 concentrations in the atmosphere in any recent past.

The CO2 is a gas that causes the greenhouse effect by generating a "thermal blanket" in the atmosphere. The higher the concentration of gas, the higher the temperature. The current data show with a 95% of certainty that the average temperature of the current years is superior to the observations along the last 2000 years. As a consequence of this increase (of about 0.6ºC in the present), there is a generalized melting of ice that can be particularly observed in mountain tops, but also in the North and South Poles. Also, the sea level has increased around 25-30 cm along the 20th century. But we are still at the beginning of this process. 

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