Global warming is not a 20th century phenomenon. It has, in fact, occurred in the past more than once, along with periods of extreme cold known as the ice ages. With so much written and reported about global warming, sometimes it's difficult to detect which is fact and which is just part of scientific scare tactics. Here are some facts about global warming that might help:

What exactly is global warming?
Global warming is basically the increase in the temperatures of the Earth's atmosphere, land masses and oceans. The Earth's surface temperature is at an average of 59F and over the last hundred years, this figure has risen to about 1F. By the year 2100, the average change in the temperature of the Earth could range from 2.5F to about 10F, enough to melt glaciers and polar ice caps.

The cause of global warming
Global warming has and will always occur naturally. Why it has become such a concern in our lifetime is due to the fact that human activities and practices have contributed significantly to its occurrence and severity. With the advent of industrialization and careless environmental practices, we have caused the increase in the average global temperatures by contributing negatively to the greenhouse effect.

This began about 240 years ago, when the Industrial Revolution was born. As more and more fossil fuels in the form of oil were mined and burned, gases as the by-product of that process began to be released in the atmosphere. Currently, it is estimated that 75% of the increase in the carbon dioxide content of the Earth's atmosphere is caused by the burning of these fossil fuels.

Global warming and the greenhouse effect
Global warming is related to changes in the Earth's greenhouse effect. Gases naturally occur in the Earth's atmosphere and act both to protect and retain heat. These gases include carbon dioxide, methane, nitrous oxide and water vapor. Of these, water vapor is the most dominant and abundant greenhouse gas.

Global warming and the greenhouse effect are not the same thing. The greenhouse effect refers to a natural process that occurs in the Earth's atmosphere. If this process is disrupted, then it could contribute to global warming.

As the sun's rays hit the Earth, heat is bounced back to the atmosphere where these gases contain the heat and keep it there to warm the planet. This is an important natural process and allows life forms to flourish and survive. Problems only occur when these gases multiply and build-up, containing heat too efficiently and thus warming the Earth's atmosphere.

As the Earth's average temperature rises, effects in its landmasses and sea water level become apparent. Polar ice caps melt along with glaciers, contributing to higher and warmer sea levels. By the end of the century, it is estimated that sea levels can increase from 4 inches to a high of about 40 inches if global warming continues unabated.

Global warming can also affect the behavior of the winds and can also contribute to a harsher and drier climate, with frequent visitings of strong hurricanes. Water from heavier rainfall will not stay long to irrigate the land, however because with a warmer climate, water on the Earth's surface will evaporate quickly. This has a significant effect on agricultural practices not only in the US but also for the rest of the world.

Another phenomenon that is equated with global warming is the El Nino. The El Nino phenomenon has occurred for possibly thousands of years and is not caused directly by global warming. However, changes in the average temperature of the planet can contribute to its severity and frequency.

Other human practices that contribute to global warming
The agricultural revolution has also contributed to global warming. As more and more communities need lands converted from forests to residential and commercial areas, biomass is reduced, contributing to the increase in the presence of carbon dioxide in those regions. Since carbon dioxide is processed by plants and trees, their absence contributes to its increase.

It is estimated that about 25% of the annual increase in the carbon dioxide found in the Earth's atmosphere is caused by extreme changes and usage of the Earth's natural resources. Other practices also include deforestation, salinization, desertification and overgrazing also contribute to global warming. However, many scientists surmise and agree that the contribution is slight and indirect.

Facing the facts of global warming
Countries all over the world have just begun to acknowledge the negative effects of global warming not only to the world's politics and economy but also to humankind in general. Many of the world's governments have encouraged implementation of measures to try to counteract the problem of global warming through careful measures and practices designed to protect and respect the environment.

How these measures will fare and contribute to the long-term maintenance of our planet, though, remains to be seen.