Global warming refers to the increasing average temperature of the earth’s and the ocean’s surface. This temperature has increased by 0.75 degrees Celsius over the last century and is expected to rise at a faster pace in the future. It may seem that this increase in temperature is insignificant and therefore the fuss about global warming is unfounded. However a sustained rise in temperatures can have very serious consequences.
One of the most touted effects of global warming is the rise in sea levels. From 1000 BCE to 1900 CE the average rise in sea level was 0.15 millimeters per year. From 1900 onwards the average rise in sea level was 1.5 millimeters per year. Presently the sea level is rising at 3 millimeters per year. Global warming causes the sea level to rise for two reasons. Higher sea temperatures cause the oceans to expand and the levels to rise. Also higher temperatures cause increased melting of ice, particularly at the poles, and therefore the sea levels to rise. Even the short-term effects of this are worrisome. Cities like London and New Orleans are already requiring storm surge defenses. The Polynesian island of Tuvalu is fast losing land area. In the long-term there would be severe inundation of coastal areas leading to a loss of habitation, agriculture and major changes in land and water quality. This is why it is essential to stop global warming.
Another effect of global warming that is already being felt is increased incidence of extreme weather. Category 4 and category 5 hurricanes have been definitely linked to global warming. El Nino is also a result of global warming. The frequency of El Nino appearing is increasing and it soon may be a permanent phenomenon. El Nino causes widespread climatic changes that lead to natural disasters like flooding, excessive rains, and bush fires.
Some other effects of global warming need to be discussed. Global warming causes a decrease in crop yields. Actual field studies conducted over 12 to 17 years have shown decreased yields in corn, soybean and rice. In fact studies showed that the yield of rice decreased by 10% for 1 degree Celsius increase in temperature. Extinction of species have also been linked to global warming. A study published in Nature in 2004 estimates that 15 to 37% of known species will be extinct by 2050. There are several species, particularly those living in cold habitats, that have a very narrow temperature range. When the temperature rises these species have either to migrate or perish. Evidence shows that some species indeed to migrate whereas others become extinct. Then there are species that have depended on the extinct species for food. These species then too face extinction.
The gravity of global warming can be gauged by the following fact. Even if we are able to control the emissions of gases that cause global warming today, temperatures will continue to rise for a thousand years. Hence we can well imagine the consequences if we are unable to control the emissions of the gases.
