A thorough discussion on the causes of global warming and if carbon dioxide is the major cause of global warming.
The effects of global warming has already been observed and experienced in different parts of the world. The melting of polar ice caps, rise of tides, and the submergence of some small islands are just some of the adverse effects of this global phenomenon (see Ten Deadly Effects of Global Warming). But in order to fully comprehend its impact to society and to the environment, we must first understand the factors that trigger its existence. What causes global warming? Which has the greatest contribution?
As cited by many scientists and environmentalists, one of the major reasons for global warming is greenhouse gases, specifically CARBON DIOXIDE. These gases serve as barriers in the atmosphere that trap heat. They are emitted from several sources such as:
a. Combustion of fossil fuels in cars, factories and electricity production. This is pointed out as the most significant cause of global warming. Fossil fuels are made up of organic matter such as coal, or oil, and when burned, they give off carbon dioxide. Likewise, mining of coal and oil allows the escape of methane, another greenhouse gas. Methane is naturally in the ground and digging up the fossil fuel also digs up the methane stored underground.
b. Landfills. Methane is created when bacteria break down organic matter under oxygen-free conditions. Landfills are excellent sources of methane where wastes buried beneath layers of wastes are decomposed under anaerobic environment.
c. Agriculture. Another potential source of methane is manure derived from cattle, poultry, pig, and other livestock. With the ever-increasing human population is the increase of food consumption which consequently demands raising of more meat-producing animals. Rice paddies are also sources of methane where organic matter is trapped underwater. Moreover, some fertilizers contain nitrous oxide, another greenhouse gas.
d. Natural “carbon sinks” like the arctic tundra, peat bogs, and wetlands. Once heat up, theses sinks may destabilize and release tremendous quantities of carbon dioxide.
e. Oceans. The ocean is a large carbon sink, holding 50 times more carbon than the atmosphere. Temperature increase can cause substantial reductions in the level of phytoplankton, the tiny plants in the ocean which store carbon dioxide, which further contributes to climate change.
f. Deforestation. All living plants store carbon and when they die and decay, they release this back into the atmosphere. Similarly, trees are important converter of carbon dioxide to oxygen, and so failure to replace cut trees means increasing carbon dioxide level in the atmosphere.
g. Other miscellaneous sources like gases used for refrigeration and industrial processes, and clathrates or the frozen chunks of ice in polar regions which are sinks of methane.
Furthermore, different greenhouse gases have different heat-trapping abilities. Methane is 100 times more powerful than CO2, nitrous oxide is 300 times, while chlorofluorocarbons can be as high as thousands times. However, they are not as concentrated as CO2 in the atmosphere so none of them add as much warm as CO2 does.
However, there are scientists and even environmentalists oppose to the idea that anthropogenic or man-made source of carbon dioxide is the prime cause of global warming. An emerging controversial output of this thesis is the 2007 documentary entitled “The Great Global Warming Swindle”. The people behind the film refuted the hypothesis of man-made climate change for the following reasons:
a. Climate change is a natural phenomenon. Over the last thousands of years, the planet has experienced cycles of warming and cooling.
b. Global temperature actually declined during the period of greatest man-made carbon dioxide production. Growth of industrialization was most rapid after the Second World War but the bulk of world temperature rise have already occurred prior to that period (1940). Actually, global temperature fell after 1940 until the 1970’s. In other words, there is no strong correlation between the level of carbon dioxide and overall world temperature.
Global temperature decreases during the period of great production of carbon dioxide by human, as asserted by the film.
c. Carbon dioxide is not a significant greenhouse gas. CO2 comprises only 0.054% of the greenhouse gases in the atmosphere and much less than 1% of this is from man-made sources. Water vapor, at 95%, is actually the major greenhouse gas and would have the largest impact in influencing global temperature.
d. Greenhouse effect in the atmosphere is not supported by meteorological data. Assuming that greenhouse effect is really occurring, the rate of warming must increase from the Earth’s surface up to the middle of the troposphere where greenhouse gases are supposed to be concentrated. Yet, satellite and weather balloon data show that the actual rate of warming in the troposphere is not higher than the rate of warming at the Earth’s surface. Hence, there is no alarming concentration of greenhouse gases in the atmosphere, enough to induce global warming. Temperature rise is only experienced on the ground which may be the result of direct solar radiation.
e. Carbon dioxide concentration lags global temperature. There is no strong evidence that CO2 concentration in the atmosphere has ever determined the global temperature. In fact, it is the reverse. Global warming has actually increased the concentration of CO2 in the atmosphere.
Carbon dioxide increases only after a temperature rise.
So what has really caused the increasing global temperature is the SUN itself. The sun is by far the greatest source of heat on the earth, and its output fluctuates between periods of high and low solar activity. High solar activity is accompanied by an increased magnetic field, manifested as visible sunspots. In 1991, the Danish Meteorological Institute revealed that there is a very strong correlation between solar activity and global temperature in the 20th century.
A fitting relationship of solar activity and global temperature.
Solar activity influences global temperature through the formation of clouds. Clouds, which serve as the planet’s shield against sun’s heat, are formed when cosmic rays from outer space reaches the Earth and meets water vapor rising from the sea. This consequently results to formation of water droplets, then to clouds. When solar activity increases, solar wind, a stream of particles emitted by the sun, also increases. This solar wind is capable of reducing the intensity of cosmic rays. Hence, a high level of solar activity means high solar wind and low intensity of cosmic rays, in effect, there will be a low rate of cloud formation, more direct solar radiation, and a higher global temperature. Evidences of this relationship show that global temperature and cosmic rays have a strong inverse correlation.
Temperature and inverted graph of cosmic rays.
There are two sides of the coin and the issue of global warming is not an exception. For some, it is an aftermath of human exploitation and the need to regulate the use, conserve, and preserve resources must be called for. For others, it is only a natural act of nature which some forces ride on, protecting cross-border political interests. But whichever causes this global phenomenon, whether it is really carbon dioxide or the sun, one simple thing is certain – there will always be a grave environmental consequence to our actions. It is a cost externality – many are carrying the cost of which few have caused to occur.