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. [...]
[...] Conclusion Having gained during our study a better understanding of the physical, chemical, geological and geophysical mechanisms involved in the greenhouse effect, we could become aware of its consequences at the biological level, not just on the human level, but also on the environmental level. And it is more appropriate to pull the “alarm bell” so that the future generations do not suffer the ill effects of uncontrolled global warming. This can not be limited to a purely scientific approach of this phenomenon but it also aims to show how serious and dangerous this can be and measures can be still taken to reduce the emission of greenhouse gas emissions, while there is time. [...]
[...] Climatologists are still reluctant to give an unqualified answer to the question "the heatwave during summers, is it actually due to the greenhouse effect?”Only the frequent repetition of such events would provide indisputable proof One can however connect with caution, the multiplication of extreme weather changes to global warming: the heat wave of summer 2003 is probably due to the greenhouse effect. In any case, it is an assumption accepted by many scientists, but there can be other factors. In fact, if the media connects the heat wave without doubt to the greenhouse effect, the fact remains that the scientific community is strongly divided on this point. [...]
[...] Thus, some permanently frozen grounds will release harmful gases (CO2 and CH4)) that were previously trapped (it is to some extent a "vicious cycle", since the emission of these gases will lead to the melting of ice through the greenhouse effect). The water cycle itself is very important: The flow of water determines the energy exchanges: Its evaporation and its condensation absorb and release large quantities of heat. In addition, water also exists in the solid form. Snow, for example, is highly reflective. [...]
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