Greenhouse gases (chlorofluorocarbons, carbon dioxide, methane, nitrous oxide, etc.)let heat in but stop it from going back out – like a windshield in a parked car.
At our current rate of creating these gases by industry, cars and burning fossil fuels, scientists predict a temperature increase of 4 to 9 degrees F by 2050. (9 degrees F separates today’s average temperatures from the last ice age.)
The United Nations Panel on Climate Change recommends that we immediately cut our use of fossil fuels by at least half. To prevent the current rate from increasing, we would have to cut by 60%.
This same panel projects that by 2050 over a million more people dying each year from malaria because of higher mosquito populations due to global warming. Already yellow and dengue fever bearing mosquitoes are found over 3000′ higher than their normal range in South America.
Other predicted results of global warming include expanding deserts, forest fires, heat waves, crop failure, erosion, mud slides, mass extinction of plants and animals, sea level increases causing flooding and damage to coastal aquifers.
The US with c. 5% of the world’s population creates 25% of the 7 billion tons of carbon dioxide that causes 50% of the global warming trend. Five tons per capita per year! US oil consumption is now the highest since 1979.
Since 1988, insurance companies paid 17 multi billion dollar weather-related claims. There had never been one even as high as $1 billion before 1988.
Before 1900, carbon dioxide in the atmosphere was stable at 280 parts per million. The concentration now is over 360 and the increase rate has doubled since 1958.
1995 was globally the hottest year in over 100 years and the driest in the UK for over 300 years.
The green house effect gas and the global warming
It is said, “if the carbon dioxide increases, the Earth becomes hot.” By what mechanism does this happen?
The gas which absorbs the infra-red lays such as carbon dioxide, water vapor, and so on, is called “the green house effect gas”.
Though these gases are contained in the atmosphere by less than one percent, the temperature of the atmosphere becomes -18°C on average if they are entirely lost from the atmosphere.
If the green house effect gases are contained in the atmosphere, while the solar radiation is not absorbed by these gases and reaches the Earth surface and warms it, the infra-red radiation emitted from the Earth surface is absorbed by these gases and the atmospheric temperature rises correspondingly. At present, since the averaged atmospheric temperature is 15°C, the green house effect gas has the effect of warming the atmosphere from -18°C to 15°C, i.e., 33°C.
If these green house effect gases continue increasing, the amount of absorption of the infra-red lays increases and the atmospheric temperature may rise correspondingly. This is why the problem of the global warming is raised.
Schematic view of the green house effect
Trend of the green house effect gases
Is the green house effect gases actually increasing?
The answer is “YES”. It has been clarified that the carbon dioxide is increasing since the industrial revolution. It is known that the concentration of the carbon dioxide has fluctuated for the past one hundred-thousand years, especially during the ice age etc. However, after the industrial revolution, it has been increasing by the rate higher than that in the past. Moreover, the increasing rate is becoming higher in recent years.
Besides the carbon dioxide, there are some other green house effect gases which are increasing in concentration due to human activities; the methane, the freon gases, the carbon monoxide, and the tropospheric ozone(*).
(*) The stratospheric ozone around the 20km height has the function of absorbing the ultra-violet rays. And if it decreases, the ultra-violet rays which reach to the Earth surface increase, which has a bad effect on living things. On the other hand, the tropospheric ozone has the function of absorbing the infra-red rays and acts as a green house effect gas.
Trend of the atmospheric temperature around the Earth surface.
While the green house effect gases are actually increasing, is the atmospheric temperature around the land surface increasing in accordance with this?
The atmospheric temperature is affected complicatedly by various factors such as the ocean or the Earth surface. Thus, the annual mean temperature of the whole atmosphere fluctuates in various time scales which range from a few years to more than several decades.
Looking at the data from 1880 to 1994, we can see that it is increasing by the rate of 0.6°C/100yr in a long range. However we have to examine quantitatively whether this increasing tendency is due to the increase of the green house effect gases or it is part of a variability on some longer time scale.
If the atmospheric temperature near the land surface rises in the whole globe, there is a possibility that it has serious effects to the human life.
It is considered that the following climate changes may occur due to the global warming.
· Desertification in the dry area and in the semi-dry area advances.
· Concentrated precipitation increases.
· Sea level rises due to the thermal expansion of sea water.
· Snowing area and frozen soil reduce.
By these, it is considered that the natural environments are affected as follows:
· Forests degenerate (especially in the semi-dry area).
· Zonal climate belts shift several hundred kilometers to the pole.
· Species which cannot adapt to the changing environments extinct.
It is feared that they have bad effects on the human life socially and economically as follows:
· Effects on agriculture, stock raising, and forestry.
· Effects on using water (increase of flood and shortage of water).
· Immigration of residents near the sea coast and on the small islands.
· Destruction of the port facilities.
· Destabilization of topography in the frozen-soil area; increase of erosion and landslide.
In order to avoid these beforehand, it is necessary to predict the change of climate when the green house effect gases increase and to consider a counterplan among all society.