According to many scientists and political organizations the production of greenhouse gases by human activities and the consequent global warming is a serious threat to the whole global environment and thereby to every one of us. But many actors have never really believed this scenario and several scientists are beginning to doubt it in some way or another after having been believers. Let us look at the facts to get to a conclusion, or at least a tentative conclusion.
The burning of fossil material like oil and coal by human activities take away some oxygen from the atmosphere and produce carbon dioxide. Carbon dioxide (CO2) absorb much more energy from the sun rays than other components of the air, and convert that energy to heat. Thus the atmosphere is getting steadily hotter if not other factors counteract the heating.
A hotter environment can furthermore melt permafrost in northern America and Siberia and then captured methane and carbon dioxide in the frozen soil will escape and accelerate the heating process.
The hotter environment can furthermore cause melting of glaciers and the polar ice and make the sea level rise and overflow populated land areas. There are also hypotheses and speculation that the warmer atmosphere will disturb all types of meteorological processes and cause disastrous weather conditions of all thinkable types.
There are however factors counteracting this doomsday scenario and there might also be some possible good effects of global warming.
First of all will much of the produced carbon dioxide dissolve into the sea and lakes and be converted to carbonic acid.
The carbon dioxide will also be utilized by algae and plants in the sea, in the lakes and in forests to grow and proliferate, and the extra produced plant material will further be utilized by animals. In other words will much of the greenhouse gas be taken out and converted to living material so that the earth actually gets greener and more living. The increased living material may be good or bad, but it will take away much of the extra carbon dioxide produced by human activities.
Industrial activities do not only produce CO2, but also finegrained dust that is the poured into the air. This dust can shield for the sunlight and reduce the amount of energy taken up from the sun rays. Increased temperature can also increase the vaporization of water from the sea and make a thicker cover of clouds, which also will reduce the uptake of energy from sun rays.
Then there is a factor seldom taken in consideration during debates about global warming, but is very prominent in the everyday political debates elsewhere. Fossil fuel is a limited resource that the globe soon will be depleted of. Therefore there is a question whether the remaining amounts of fossil fuel really can rise the global temperature to a threatening level, and perhaps rising prizes of fossil energy will take away the threat even before the remaining fuel is consumed.
After having listed the possibly threatening factors and the counteracting ones, the time is come to see if the amount of atmospheric greenhouse gases is really increasing and if the global temperature averaged over all areas and over the year is really increasing. The time is also set to rise the question weather such a temperature rise really is a threat or instead a good thing.
Since 1959 the amount of carbon dioxide has been measured continually on the top of Mauna Loa at Hawaii, a place where no nearby source of pollution is disturbing the result. The measurements are plotted in a published graph, named the Keeling curve after the supervisor of the project David Keeling. The measurements show that the averaged atmospheric CO2 concentration has increased steadily from 310 ppm to 390 ppm from 1958 to now.
Before 1958 one does not have good enough data to draw any firm conclusion. The newer figures seem to be significant, however, and one must conclude that there is a probable increase in the CO2 concentration. Since one does not know about any other great enough source of this increase, combustion of fossil materials by human activities is the most probable source.
But has really the average temperature also increased? The year-average surface temperature on Earth is said to have increased from – 0.6 degrees C in 1880 to 0,6 degrees C in 2010. From 1977 such measurements have been done by data obtained from satellites with extremely accurate methods that are calibrated through direct observations made at surface level.
The temperature evidence has however great problems. Before 1979 the calculations were based on data from unevenly distributed weather stations and ship positions and many measurements were done near cities that will always generate a higher temperature than land areas.
The average measurements also vary greatly from year to year and do not show a smooth curve like the concentration of carbon dioxide. In the periods 1880-1920 and 1940-1980 has the temperature declined somewhat instead of increasing. Looking at the evidence on a whole one is still inclined to conclude that there is a global temperature increase going on.
But have the temperature increase had practical consequences? Will these consequences be serious, or will they on the contrary be mainly beneficial? The last years the weather have been wild and unstable in many parts of the globe, with hurricanes, abruptly fluctuating temperatures, brutal showers and thunder, extremely dry and hot local periods, extreme local frost, floods, avalanches and the like. But such brutal weather incidents have come and gone throughout the whole history, and they can hardly be taken as evidence for disastrous effects or the global warming.
More significant is the gradual reduction of the north pole ice, Greenlandic glaciers and Himalayan glaciers throughout the last decades. Since 1979 the area of the North Pole Ice cap has shrunk more than 20%, for example. The sea level height also seems to gradually increase.
These changes have a clear negative effect upon the habitat of certain polar animals. But what is negative at one hand, can be good at another hand. The reduction of the ice can open new living areas, new food sources and new opportunities for economical exploitation both for humans and animals. The general temperature increase might also make the condition of living better for people in northern areas, and make these areas more fertile.
As seen by the above summary, there is probably a global warming effect so far, and this effect will likely increase. But it is by no means certain that the effect will get overwhelmingly negative. The overall effect for the human population might as well be positive.
It is also a great question whether the remaining fossil energy sources are great enough to give a huge impact upon the global environment at all.
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