As the earth continues to experience change, sea levels will continue to rise. Global warming will continue to increase them over at least the coming century. Measurements from the period of 1993-2003 indicated a mean rate increase of 3.1 mm/year. (Bindoff, NL et al., "Observations: Oceanic Climate Change and Sea Level", Climate Change 2007)

Centuries ago, the sea level was far lower compared to what it is today. The end of the last deep freeze resulted in continents joining together with exclusions that included Iceland, Australia and a few islands in the Pacific. After the ice meltdown, the coastlines were submerged and from about 6,000 years ago and onward, the sea levels remained constant.

The most natural causes of a rise in sea levels include the melting of ice on land, water created from reserves of oxygen and hydrogen in the earth's crust, water from deep space, and when land collapses due to thermal expansion. When volcanoes erupt, water from below the surface of the earth is ejected in the form of steam and flows to the oceans. This event also contributes to their rise, though not that dramatic. Massive collapses of land can also be a reason for their rise. Tsunami events that swept the world were said to be a result of these events.

Because of the green house effect, sea levels have been on the rise again. Scientists have determined that the rise is a result of human activities. Greenhouse gasses are created and released by human activity, triggering changes in the them. The layer of gas protecting the earth from the harmful sun rays has been greatly affected by the increase of fossil fuel burning. More sun rays are being kept inside the atmosphere and thus the earth becomes warmer. Due to the rise of temperature, large masses of ice in the North and South Pole are starting to melt causing them to rise faster than they should.

Sea levels falling and rising is very much a natural phenomenon. The Mediterranean Sea and the Black Sea were once said to be dry lands until the sea levels rose and changed everything. Unfortunately global warming is affecting the planet's natural changes. Global warming will continue to increase them at a much faster rate than normal. Melting polar caps and ice sheets are going to have a deep impact on our way of life. Thermal expansion, the main contributor to this rise, is expected to be the major contributor to rising sea levels.

In order to combat global warming, we need to understand how our planet functions. With the appropriate environmental policies, we may be able to slow global warming. It is essential that we leave a healthy planet for our children.

Terry Mitchell is the owner and operator of Foxrater - http://www.foxrater.com - the web's top free insurance quote site. It allows people to enter their zip code and compare the rates of auto, homeowners, health, and life insurance companies doing business in their area.