The Greenhouse Effect: Definition, Causes, and Consequences
Environmental hazards such as storms, tropical cyclones, droughts, etc. have been affecting us for generations. In France, the temperature reached its highest point last summer and reports showed that the August of 2003 experienced a high heat wave with the most dramatic consequences: the average number of victims of the heat wave were more than15,000.
We are a part of these major climatic changes and experience them in our day to day lives which give us way for thought, since they are of unprecedented geographical scope and unique duration; since the mid-19th century.
The heatwave: Is it due to the greenhouse effect? Will this phenomenon happen again?
These are two questions that led us to opt the greenhouse effect as the subject for discussion; this is a subject that falls under the topic of the natural and technological hazards. These questions constitute the base of our problem. First, we will have to understand what the greenhouse effect is and we need to determine the dominant factors of the greenhouse effect. We will rely on both "conventional" documents (newspapers, periodicals, textbooks, websites, encyclopedias) as well as on new approaches (concrete experiments, experts meeting at the Royal Meteorological Institute and use of a specialized video cassette)
The average temperature of our planet results from the balance between the flow of radiation from the sun and the infrared flow of radiation back into space, it speaks of radiation balance.
Today, the planet earth is undergoing global warming, which is relatively modest at presentbut according to specialists, this will accelerate over the coming years and can lead to undesirable consequences for the future generations.
Thermal transmissions from planetary surfaces are absorbed by the atmospheric greenhouse gases and re-transmitted in all directions, and this phenomenon is known as the greenhouse effect. The greenhouse effect is more or less known by all and one can can easily understand and imagine what it means, what it is. Greenhouse effect has its advantages but its excess can be dangerous. The average ground temperature is around 15°C approximately not including the greenhouse effect and 18°C including the greenhouse effect. Greenhouse gas emissions are essential for life.
Much of the solar radiation passes directly through the atmosphere to heat the earth's surface. The earth, in turn, "returns" this energy to space in the form of infrared radiation. Water vapor (H2O), carbon dioxide (CO2) and other gases (so-called "greenhouse gases" or GHGs) absorb this radiation by the earth, preventing energy from passing directly from the earth's surface into space and thus heating our atmosphere. Therefore, if we increase the atmospheric concentration of greenhouse gases and if the inputs of solar radiation inside the "greenhouse" remains constant - the temperature will rise.
Approximately 70% of the solar radiation is trapped in the atmosphere.
The average lifespan of the greenhouse gases is of several centuries, forcing the struggle against their emissions to be based on the long term.
The differences in the infrared absorption by the gases given should not be overlooked if one wants to really understand the situation in order to develop effective solutions to fight against the greenhouse effect and suggest an interesting experiment: We can note various consequences of the infrared radiation when compared to several gases (non-absorbent, and very low absorbency).
[...] It is the transformation of light energy into chemical energy, by consuming carbon dioxide and water and then producing oxygen molecules, to be released into the atmosphere. Depending on its nature (agricultural forests, farmland), it stores more or less heat, water molecules and CO 2. Carbon dioxide stimulates the growth of plants. Result? "Higher, faster, but not necessarily stronger." Some saw a new splendid and natural response in nature to human aggression: Trees and plants improve the process of photosynthesis and thus absorb more of the carbon emissions. [...]
[...] Detailed diagram of the mechanism of the greenhouse effect and its consequences at the biological and geological levels during the glacial and interglacial periods: (The term "albedo" is defined in the glossary at the end of the report) Main greenhouse gases One can first mention about the water vapor (H2O) and the clouds which retain heat. The main greenhouse gases emitted by human activities are: - Carbon dioxide (CO2) - Methane It retains 20 times more the infrared radiation than CO2 and remains approximately 100 years in the atmosphere. [...]
[...] Greenhouse gas emissions are produced naturally by the environment and also (especially since the 1860s) by the human activities (combustion of fossil fuels, transport, industry, agriculture). This is known as the anthropogenic or human impact on the nature (degradation of environment by humans) Change in atmospheric levels of greenhouse gas emissions since 1750. (Compiled by J. Chappellaz) Combustion changes the composition of the atmosphere by adding carbon dioxide and other gases. Moreover, the destruction of vast tracts of forests leads to the emission of large amounts of carbon (stored in trees and forest soils) and also ends the process of photosynthesis (the balance between the respiration and emission of greenhouse gases’ emissions). [...]