Greenhouse effect
Kategorie: Biológia (celkem: 966 referátů a seminárek)
Informace o referátu:
- Přidal/a: anonymous
- Datum přidání: 23. února 2007
- Zobrazeno: 2172×
Příbuzná témata
Greenhouse effect
Greenhouse effectDuring the last century, Earth’s temperature has risen by 0,5ºC. This global warming is a consequence of greenhouse effect, caused by nothing else but human activities.
I would divide the greenhouse effect into two main types: the “good” and the “bad”. I even think there is no mid- type or sort of golden middle way – greenhouse effect can be only good or only bad (an explanation will be given later). Earth’s atmosphere is very similar to greenhouse glass - it is transparent to sunlight, which warms it, but it keeps a part of both earth and sunlight’s warmth from escaping back into free space. This effect is due to several greenhouse gases, including carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), chlorofluorocarbons (CFCs - freons) and water vapor. Without these gases and the “good” greenhouse effect, the Earth would be very cold (different sources say different numbers, but surely it would be deeply below zero and even oceans would be frozen) and there could be no life on it. Nowadays, the atmospheric concentrations of greenhouse gases are rising as a result of human activities - that is how good (natural) greenhouse effect becomes bad or even dangerous for Earth and people living on it. Since the agricultural and industrial boom (more than 200 years ago), we have produced a huge amount of carbon dioxide and other greenhouse gases: the carbon dioxide concentration has risen by almost 30% (and is still rising by 0.4% annually), methane levels have more than doubled (a rise of 0.6% annually) and nitrous oxide levels are increasing as well (by 0.25% annually). All these are released primarily when we burn fossil fuels like coal, oil, petrol, natural gas and wood, as well. The natural way in which carbon dioxide is transferred back into oxygen is, being breath by green plants - mainly in rain forests. In the last few years, people have burned (and still are burning) huge areas of rain forest in the South America and central Africa for the purpose of agricultural aims. This means there are fewer threes, and of course, more carbon dioxide.
Another ways, in which greenhouse gasses are being produced, are, for instance, biomass burning and fertilizer use (production of nitrous oxide), using aerosols and refrigerants containing CFCs, and photochemical smog producing ozone (it may look like a good activity, but this ozone is the one collecting in the lowest atmospheric regions that acts as very strong greenhouse gas).
The “bad” form of greenhouse effect and the next rise in temperature, which is predicted to be between 0.8 and 4.1ºC until the year 2030, are understood as scarecrows due to their very dangerous consequences. They will be accompanied with changes in global climate. Firstly, weather will at least change or maybe even absolutely invert. Rains will fall rarely but in greater intensity; dry places like deserts, for instance, will enlarge and become drier. Some areas near the coasts will be cloudier and wetter and there will be more storms. Inland areas will have a little more rain, but because the temperature will be higher, they will be drier. Secondly, some glacial and surface ice and snow will melt, raising the height of world's oceans by as much as 20 centimeters until 2030 and 65 centimeters until the end of this century. This will cause floods in many low-lying areas on the coasts, presently occupied by hundreds of millions of people. Thirdly, a lot of clouds will appear. This issue is very discussed and actually it is very unsure what may happen then. Maybe the cloud layer, by reflecting sunlight back into space, will make Earth cooler again. But will there not appear a magical ring in which Earth will be spinning by firstly cooling and then warming? Or will the temperature not decrease so much that there could be no life on the Earth?
After realizing the seriousness of the situation, civilization started doing actions for preventing the greenhouse effect. There are many possibilities how to stop immediately the warming. Some of them are “smaller”, mostly household activities that everyone can join. Those are sorts of ”turn off the light when you are leaving the room“, “recycle”, “use unleaded fuel”, “travel with a bike instead of driving a car“, ”install solar panels on your house “ etc. The other types are much bigger, planned by scientists activities. I mean, for instance, “burying” the carbon dioxide under earth surface, pumping a huge quantity of iron and plankton in the oceans, which would then absorb the CO2 from the air, or pumping directly the carbon dioxide there, which in the water could become liquid. The problem is that not every country has the financial possibilities (the costs for extracting the CO2 from the air are really huge), or, like USA for example, the want to do so. Although representing just 4.5% of Earth’s population, USA annually produces 25% of the greenhouse gases released in the air. There is a Protocol composed in 1997 in Kyoto that is signed by almost all countries in the world. It supposes them to lower all the carbon dioxide emissions at least by 5.2% until the year 2012.
Despite signing it, USA actually does not stop any CO2 emissions, saying that it could seriously harm its industry. Is that the right way how to stop greenhouse effect?
The greenhouse effect is a very dangerous thing, which the civilization should be no longer toying with. When not stopped or at least rapidly reduced immediately, it can cause great worldwide problems in the future that we are even not able to predict yet.