A greenhouse is a structure that regulates the temperature and humidity within it. The earth’s atmosphere is like a greenhouse enveloping this massive planet. The earth is constantly absorbing heat from the sun. This heated earth emits the heat in the form of infrared radiation which in its turn is absorbed by the greenhouse gases and re-radiated back to the earth’s surface.
What are the various greenhouse gases? Carbon dioxide, methane and water vapour amongst many others. Ozone, nitrous oxide and fluorocarbons are other greenhouse gases. These gases have always remained in the atmosphere. But ever since the Industrial revolution and the burning of fossil fuels (coal, natural gas and oil) began, man has directly contributed to the increase in carbon dioxide, methane, ozone and chlorofluorocarbons (CFCs).
About half of the greenhouse effect is due to water vapour but humans do not affect the amount of water vapour in the atmosphere and thus water vapour is not responsible for climate change.
Carbon dioxide is responsible for three fourth of the global warming. Normally, carbon dioxide that is emitted from various sources (breathing by humans and animals, fossil fuel burning, active volcanoes) is also absorbed by the planet. Plants use carbon dioxide and it is also absorbed by the oceans: the “sink” mechanism. Carbon dioxide dissolves in the ocean water and is absorbed by phytoplankton. But since the Industrial revolution, the amount of carbon dioxide in the atmosphere has increased by over 50 percent and has overwhelmed the balance mechanism. Besides fossil fuel burning, carbon dioxide is also released by industry and agriculture activities.
Methane is also released by similar processes. Methane gas increased by 150 percent since the Industrial revolution. Though atmospheric air contains far more carbon dioxide than methane, methane gas traps 30 fold higher amount of heat than carbon dioxide and that is why, it is extremely important too. Where does methane originate from? Natural sources and human related resources. Natural sources include water bodies, wetlands and plant eating animals. Human related sources include fossil fuels, agriculture (rice farming) and livestock (cattle). One of the major sources of methane is the beef and dairy industry. Cows, sheep, goats and giraffe are all a class of animals termed as ruminants. These animals have a special stomach with four chambers. They eat grass and leaves and their food is regurgitated back many times and chewed over and over again. Along with digesting the food, carbon dioxide and methane are produced which are either mainly belched or burped out and the remaining gases passed out through farts. A single cow produces 154-264 pounds of methane per year. The 1.5 billion cattle who are raised specifically for meat production worldwide, collectively emit 231 billion pounds of methane annually into the atmosphere. This number does not include any other livestock.
If the current rate of greenhouse gas emission continues, the earth’s temperature will increase by 2 degrees centigrade between 2040 and 2070, which is very dangerous indeed.
