As a reminder, last week we spoke of air pollution and mentioned that one of the impacts of air pollution is imposition of changes in greenhouse gases. We will study this phenomenon, today.

One of the topics of importance which has caught the attention of many in recent decades is greenhouse gases. They are referred to as greenhouse gases because they create an atmosphere similar to the atmosphere of greenhouses, around Earth. In greenhouses, sunrays enter the environment. However, due to the presence of glass layer, part of these sunrays return into the greenhouse. In this manner, the greenhouses are warmer than outside. A similar development takes place in Earth’s atmosphere. When sunrays reach the ground, they are partly absorbed and warm up the ground, because the surface of Earth is much colder than that of the Sun. Hence, the waves are distributed with a higher wavelength compared to the sun. Moreover, the sunrays are distributed with a higher wavelength after hitting the surface of Earth. Furthermore, Earth’s atmosphere better absorbs waves with higher wavelengths. In this manner, the waves returning from the ground are absorbed in the atmosphere. Absorption of these waves warms up the atmosphere.

Meanwhile, these reactions are not harmful on their own. Prior to interference of mankind in nature, Earth’s atmosphere partly kept sunrays in itself, which appropriately warmed our Planet for existence of living creatures. In the absence of greenhouse gases, the average temperature of Earth would have dropped by 15 to 30 degrees centigrade. However, upon the interference of mankind in nature, and upon the production of greenhouse gases, the rate of absorption of sunrays surged. Upon the emergence of industrial revolution and mounting usage of fossil fuels, the combination of gases in the atmosphere changed and the rate of absorption of sunrays went up.

Nearly all of those, who are familiar with greenhouse gases, have heard of carbon dioxide. However, carbon dioxide is only one of greenhouse gases. The greenhouse gases include water steam, methane, and ozone. The fact of the matter is that water steam, carbon dioxide, methane, and ozone are the most effective greenhouse gases. The main components of the atmosphere, which are nitrogen and oxygen, are not greenhouse gases, because their molecules neither absorb nor reflect the infrared rays and therefore no change takes place in these molecules. Among the greenhouse gases, carbon dioxide has generated major concerns. This gas is emitted as the result of human activities. The density of carbon dioxide in the atmosphere in the beginning of the industrial revolution stood at 280 units. However, its density in atmosphere has currently reached 350 units and is expected to surge to 450 units by the year 2050.

When we speak of greenhouse gases, we take into account the impact of these gases on the environment. The impact of greenhouse gases was initially detailed in the 19^th Century AD by Jean Fourier. According to this scientist, the greenhouse gases lead to global warming due to passage of sunrays through these gases, and absorption or reemission of the warmth resulting from global warming, by these gases.

The majority of human activities produce greenhouse gases. After the emergence of industrial revolution and invention of several industrial machines, mankind changed the climate of the planet with his agricultural and industrial activities. In fact, with the beginning of industrial revolution, people’s lifestyle changed, and upon the growth of population and surging usage of oil and coal, the combination of gases in the atmosphere changed. Based on a body of research, the wastes resulting from fossil fuels, worldwide, emit 25 billion tons of carbon dioxide into the atmosphere per year, which in fact amounts to emission of 800 tons of carbon dioxide worldwide per second. Meanwhile, the combustion of agricultural wastes contributes to emission of carbon dioxide, which in addition to mounting the greenhouse phenomenon, induces the exit of carbon from food chains, thereby leaving negative impacts on the environment and the ecosystems.

One of the evident impacts of greenhouse gases is global warming. Studies which have been carried out go to show that in the past century, the average temperature of Earth has increased between 0.18 to 0.74 degrees centigrade.

The Intergovernmental Panel on Climate Change (IPCC) which is an accredited reference organization on climate change and global warming, in a recent report, has pointed out that the root cause of global warming as of mid-20^th Century has been the emission of greenhouse gases, which human activities have generated. Also, research shows that in case of continuation of this situation, by the year 2100 AD, Earth’s temperature will rise between 1.1 to 4.6 degrees centigrade.

In accordance to scientific studies, if the emission of greenhouse gases, especially carbon dioxide, continues in the current rate, Earth’s temperature will rise between 1 to 2 degrees centigrade by the year 2030 AD. This global warming would induce major changes in Polar Regions, melting icebergs and raising the level of water in oceans, causing the inundation of many coastal regions and farmlands. Also, based on predictions, numerous regions in India and Bangladesh and some European cities which are situated in coastal regions will be endangered.  The Euro News TV Network, in one of its reports, mentioned the detrimental impacts of global warming due to emission of greenhouse gases and warned that in case of prolongation of the current situation till the year 2080 more than two billion people in the world will suffer from shortage of water.

Experts believe that even if the world stops emission of greenhouse gases as of now, Earth’s temperature will raise by one centigrade in the next twenty years. This, in the long run, can cause major climate changes and leave destructive impacts on the globe. These climate changes would be coupled with a surge in natural disasters, such as flashfloods and thunderstorms. If the global warming prolongs, ailments resulting from heat, such as malaria, would soar, mainly affecting children and elderly in poor countries. Moreover, upon global warming, sources of food for mankind would decrease. Global warming also sparks shortage of fresh water. These changes would also negatively impact animals and plants, especially if these changes take place swiftly. For instance, birds and animals who migrate to other regions may not find an appropriate destination.

Meanwhile, in accordance to latest UN report, roughly 70% of global greenhouse gases are generated by industrial countries.

MR/ME