Global warming is generally understood as a rise in the average temperature of the atmosphere, oceans and landmasses of the earth. Ever since the earth was formed approximately 4.65 billion years ago, it has continually undergone changes in temperature. In recent years however, the issue of global warming has become a cause for concern as the earth appears to be facing rapid warming, threatening its very existence. The average surface temperature of the earth is about 15°C. Over the last century this average has risen considerably. Scientists have predicted a further warming of up to 5.8°C. This high degree of warming threatens to melt snow caps and glaciers and also warm the oceans, which will consequently expand the ocean volume, flooding coastal areas and perhaps entire islands.
Scientists have cited a number of causes of global warming, which they believe is mainly a result of human activities. The principle cause of global warming is believed to be the burning of fossil fuels like coal, natural gas etc. which release into the atmosphere carbon dioxide and other harmful gases also called greenhouse gases. With the atmosphere getting loaded with these gases, the earth begins to act as an insulator, retaining the heat sourced from the sun.
Popular Causes of Global Warming
Carbon dioxide (CO2) is the chief greenhouse gas. Majority of the carbon dioxide emissions are a result of burning of fossil fuels to generate electricity. Coal accounts for over 90% of these emissions. Other important sources of carbon dioxide emissions are combustion engines in vehicles, industrial smokestacks, airplanes and building structures.
Following carbon dioxide, methane (CH4) is another important greenhouse gas, believed to be even more effective than carbon dioxide at trapping atmospheric heat. Methane is emitted from several sources like production and transport of coal, rotting organic waste and flooded rice fields. Since the Industrial Revolution in the 1700’s, the emission of methane has nearly tripled.
Water vapor is also an important greenhouse gas. In fact it is the most abundant and powerful greenhouse gas, as it is released into the atmosphere through evaporations from oceans, rivers and lakes. Also, as the earth heats up, humidity increases, allowing the atmosphere to hold more water vapor.
Nitrous oxide (N2O) is another greenhouse gas which is produced by oceans and rainforests, burning fossil fuel, using fertilizers in agriculture and plowing farm soils. It is a powerful insulator trapping about 300 times more heat than the same amount of carbon dioxide.
Apart from carbon emissions caused by humans, Deforestation is the most important cause of increase of CO2 in the atmosphere. Destruction of millions of trees every year is resulting in the release of millions of tons of CO2 every year. Temperate forests which absorb nearly two million tons of CO2 annually are also gradually depleting.
In addition to these, there are numerous other gases released into the atmosphere every year by manufacturing units, industries, polluting vehicles and so on. The more the gas in the atmosphere, the more the heat trapped, resulting in rapid global warming which has become an international concern. The potential consequences of global warming are so great, that researchers and environmentalists have called for immediate, collective action to save the planet.
