The difficulties that we face today with respect to global warming and climate change lie mainly in the increase of greenhouse gases in the atmosphere of our planet, but we have to understand well what these gases are and what makes them cause the aforementioned problems. Let’s now see in detail what greenhouse gases are and what they cause.
What are greenhouse gases and what do they cause?
A greenhouse gas is defined as any gaseous compound that has the ability to absorb infrared radiation, trapping it and retaining the heat it produces within the atmosphere. Greenhouse gases are responsible for the so-called greenhouse effect, one of the main causes of global warming.
Solar radiation and greenhouse effect
Global warming is certainly not new: the foundations of this scientific phenomenon, in fact, had already been laid in 1896 by Svante Arrhenius, a Swedish physicist and chemist, winner of the Nobel Prize in Chemistry in 1903. One of his publications in the Philosophical Magazine and the Journal of Science was the first in which the negative effects of carbon dioxide were quantified.
The sun bombards the Earth with a large amount of radiation that hits the atmosphere in the form of visible light, ultraviolet (or UV) rays, infrared (or IR) rays, and other types of radiation that are invisible to the human eye. According to NASA, thirty percent of solar radiation that enters Earth’s atmosphere is reflected back to space by clouds, ice, and other reflective surfaces. The remaining seventy percent, on the other hand, is absorbed by the oceans, the ground, and the atmosphere itself. As they are heated by radiation reaching them, the oceans, soil, and atmosphere release heat in the form of infrared radiation, which is sent into space. Also according to studies carried out by NASA, the balance between incoming and outgoing radiation maintains the global average temperature around fifteen degrees Celsius. The exchange of incoming and outgoing energy is precisely defined “greenhouse effect”, since it globally replicates what happens in a common greenhouse. Incoming UV rays easily pass through greenhouse glass (our atmosphere) and are absorbed by plants and other indoor surfaces (oceans, soil, and atmosphere). Infrared radiation emanating from internal surfaces is weaker: it is difficult for them to pass through the glass and leave the greenhouse. They then remain trapped inside it, heating it up.
Why do greenhouse gases contribute to global warming?
The gases that absorb infrared radiation inside the atmosphere are defined as “greenhouse gases”, precisely because they are mainly responsible for the development of the homonymous effect. The main greenhouse gases are water vapor (H2O), carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Although oxygen is the second most abundant gas on our planet, it does not absorb infrared radiation. Although the greenhouse effect is considered by some to be a natural process that has always existed, it can easily be shown that in the last century the amount of gases that allow its development has increased dramatically. The main culprit of all this is the Industrial Revolution , which caused the increase of carbon dioxide in the atmosphere.
Fluorinated gases (gases to which fluorine has been added), including hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride , are produced during industrial processes and are also counted as greenhouse gases . Although present in a very low concentration, these gaseous compounds trap heat very efficiently and have a high global warming potential. Among the greenhouse gases we can certainly also include chlorofluorocarbons , better known as CFC gases, which were used in refrigeration systems but are now banned after an international agreement.
Three main factors determine the degree to which greenhouse gases affect global warming:
- abundance in the atmosphere
- residence time in atmosphere
- global warming potential
Carbon dioxide, for example, has a significant impact on global warming precisely because of its abundance in the atmosphere and because of the long time, thousands of years, that it remains there. Methane’s radiation absorption rate is twenty-one times higher than that of carbon dioxide, which is why it is also a powerful greenhouse gas, although it only remains in the atmosphere for about ten years.
Greenhouse gases: the sources
Some greenhouse gases, such as methane, are produced through agricultural practices ; others, such as carbon dioxide, are emitted by natural respiratory processes and especially by the use of fossil fuels such as coal, oil and natural gas. Another process that causes a significant release of CO2 is deforestation . When trees are cut down to produce other goods or heat, they release the carbon that has been deposited inside them as a result of the photosynthesis process. Every year, deforestation causes the release of almost 1 billion tons of carbon into the atmosphere. Replanting helps reduce the formation of carbon dioxide in the atmosphere, as it is absorbed and stored inside by plants.
However, it should be noted that forests cannot completely reduce the amount of CO2 released into the atmosphere after the use of fossil fuels. Reducing its consumption, therefore, continues to be essential to improve the health of our planet. All this is shown by the data: worldwide, since the Industrial Revolution in the late 2000s, the amount of carbon dioxide produced has increased by 38%, while that of methane by 148%. Most of this increase has occurred in the last fifty years. The global warming that we are witnessing compromises atmospheric circulation and negatively impacts disturbances, which are essential for global climate balance. If greenhouse gases continue to be emitted relentlessly, we can see the formation of unwanted phenomena on the surface of our planet ( rising sea levels, extinction of plants and animals and many others).
How to fight against greenhouse gases?
The path that renewable and green energies show us is undoubtedly the correct one. Technological advancement has allowed the development of new tools to produce energy in an eco-sustainable way. Installing a photovoltaic system on the roof of your house or business, for example, can be a winning option, both for our pocket and for the environment. Taking advantage of the presence of phenomena and elements such as the sun, wind and water will allow us to reduce the consumption of fossil fuels and, consequently, introduce less and less CO2 into the atmosphere.