GreenHouse Gas (GHG)
A GreenHouse Gas (GHG) is a gas that absorbs and emits radiant energy within the thermal infrared range. Greenhouse gases cause the greenhouse effect. The primary greenhouse gases in Earth's Atmosphere are water vapor, carbon dioxide, methane, nitrous oxide and ozone. Without greenhouse gases, the average temperature of Earth's surface would be about - 18C (O F), rather than the present average of 15 Celcius (59 Ferenheit). The atmospheres of Venus, Mars and Titan also contain greenhouse gases.
The Main Gases in Earth's Atmosphere
The main gases in Earth's Atmosphere are : 78% of Nitrogen, 21% of Oxygen and 0.9% of Argon gas. The other gases are: CO2, NO2, CH4 and Ozone. They are trace gases that account for almost a tenth of 1% of Earth's Atmosphere.
GreenHouse Gas (GHG) Impacts
The contribution of each gas to the greenhouse effect is determined by the characteristics of that gas, its abundance, and any indirect effects it may cause. For example, the direct radiative effect of a mass of methane is about 84 times stronger than the same mass of carbon dioxide over a 20-year time frame but it is present in much smaller concentrations so that its total direct radiative effect is smaller, in part due to its shorter atmospheric lifetime. On the other hand, in addition to its direct radiative impact, methane has a large, indirect radiative effect because it contributes to ozone formation.
Aside from water vapor, which has a residence time of about nine days, major Greenhouse gases are well mixed and take many years to leave the atmosphere. Although it is not easy to know with precision how long it takes greenhouse gases to leave the atmosphere, there are estimates for the principal greenhouse gases. The atmospheric lifetime of a species therefore measures the time required to restore equilibrium following a sudden increase or decrease in its concentration in the atmosphere. Individual atoms or molecules may be lost or deposited to sinks such as the soil, the oceans and other waters, or vegetation and other biological systems, reducing the excess to background concentrations. The average time taken to achieve this it the mean lifetime.
Carbon dioxide has a variable atmospheric lifetime and cannot be specified precisely. The atmospheric lifetime of CO2 is estimated of the order of 30-95 years. This figure accounts for CO2 molecules being removed from the atmosphere by mixing into the ocean, photosynthesis, and other processes. However, this excludes the balancing fluxes of CO2 into the atmosphere from the geological reservoirs, which have slower characteristic rates. Although more than half of the CO2 emitted is removed from the atmosphere within a century, some fraction (about 20%) of emitted CO2 remains in the atmosphere for many thousands of years. Similar issues apply to other greenhouse gases, many of which have longer mean lifetimes than CO2, example Nitrous Oxide has a men atmospheric lifetime of 121 years.
Although the greenhouse effect is a natural phenomenon and is one of the reasons that life can exist on Earth (as greenhouse gases keep the surface of the Earth warm enough for us to live here: without them the Earth would be about 33 degrees centigrade colder on average, rendering many places inhospitable), the greenhouse effect is getting worse. This is having knock on effects, causing problems such as global warming, where the average temperature of the Earth is steadily rising over the years.
There are a number of reasons that there more of the normal greenhouse gases are being poured into the atmosphere. There are several causes of extra greenhouse gases in the atmosphere.
2. Increase in Population
Increase in population has further taken toll on the environment. With the rise in population, the demand for fuel, oil, gas, house, transport also increases. All these in some way or the other raises the CO2 level, which in turn increases global warming.
3. Burning of Fossil Fuels
However, since we have started using fossil fuels for our cars, electricity and heat, for instance, we have started pouring out thousands of metric tons of carbon dioxide into the atmosphere each and every year. The burning of fuels like coal, oil, wood, gas produce carbon dioxide which is released in to the atmosphere. The carbon that was once contained within the Earth, therefore, is being released into the atmosphere, and this carbon dioxide, as previously stated, is a greenhouse gas that causes the heat of the sun to be kept in the Earth's atmosphere. CO2 is one the gases primarily responsible for the greenhouse effect. Waste material produced from factories and industries which contain toxic substances is dumped in the open air which produce harmful gases. Burning fossil fuels, therefore, is directly contributing to the greenhouse effect, and in a big way.
Unfortunately, however, because we are cutting down so many trees every year and either not replacing them at all or not growing enough new trees, these plants cannot help to regulate the amount of oxygen and carbon dioxide in the atmosphere. This means that there is more carbon dioxide than ever before in the air and it is contributing greatly to the greenhouse effect.
Deforestation, on the other hand contributes effectively towards global warming. Due to increase in real estate projects and new development, more trees are chopped off daily. Trees maintain balance of the environment as they intake carbon dioxide and release oxygen. Since, the growth of new plants doesn't happen at that rate at which old plants are chopped off, the result is that are fewer trees to perform left to maintain ecological balance.
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@ Jackie San