We've heard so much about global warming for so long that most people either accept it as fact or ignore it as hype. Well, Al Gore is right. The Earth is indeed growing warmer. His assumption that the cause is due to mankind's polluting the environment is faulty, however. It turns out that the major culprit of the earth's increasing temperature has less to do with man's dirty habits and much, much more to do with gravity and celestial dynamics. The bottom line is this: The Earth is closer to the Sun than it has been in years. Changes in Earth's position and orbit over the next few centuries will cause it to move even closer to the Sun, causing our environment to warm up. In as little as a hundred years, Earth's climate will have changed so drastically that life as we know it may be unable to survive. And mankind may be unable to reverse the process.
Elementary school children are taught that the Moon revolves around the Earth, the Earth revolves around the Sun, and the Sun revolves around the central point of our Milky Way galaxy. Simple enough, yet the gravitational influences each of these systems exerts on the Earth causes tiny fluctuations in our path through the universe. In particular, the Earth's orbit around the Sun changes as a result of these forces.
Scientists have known about something called the "Milankovitch theory" for years. Named after the Yugoslav mathematician who first proposed it, it is the astronomical or orbital theory of climate variations. The theory identifies three types of variation in the Earth's orbit around the Sun which could act as mechanisms to change the global climate: changes in the tilt of the Earth's axis (obliquity), changes in the shape of Earth's orbit (eccentricity) and the shifting of the equinoxes (precession). The three orbital variations together affect the total amount of sunlight received by the Earth, and distribution of that sunlight at different latitudes and at different times. These changes occur over periods of tens of thousands of years, and the climate changes resulting from these orbital changes occur over similar time periods. The Milankovitch theory of climate change has been used to explain the global climate of the last two million years, with changes between warmer interglacial periods and colder Ice Ages occurring over a 100,000 year cycle, as well as predict upcoming trends in climate change.
Obliquity is the tilt of the Earth's axis as compared to the plane in which the Earth revolves around the sun. Currently the Earth's axis is tilted 23.5 degrees. That value can vary between 21 and 25 degrees in a cycle that takes about 40,000 years to complete. Eccentricity is the shape of the Earth's orbit around the sun. It can vary from nearly circular to more elliptical, or oval-shaped, in a 100,000-year cycle. Over the past few centuries Earth's orbit has become more elliptical, which means we approach the sun more closely than we do when the orbit is more circular. Precession is the tendency for the Earth's axis to "wobble" as it spins, much like a top does. One "wobble" takes 23,000 years to complete and affects when seasons occur on Earth.
The combination of all three cycles at this point in time means that the Earth's orbit is closer to the Sun than at other times in the past. As a result the Earth is receiving as much as 30 percent more sunlight than it has in the past several hundred years. More sunlight means more heat, which means more warming, which means...well, ask Al Gore.
Scientists are divided on the accuracy of the Milankovitch theory, and many vehemently insist that our current warming trend is the result of mankind's mismanagement of the environment rather than natural causes. I can't blame them. After all, if global warming is man's fault, then man can make changes to reverse the effects of his mistakes. However, if it's all due to nature, there may be nothing we can do except sit back and turn up our air conditioners. That doesn't go over well, especially when you tell the masses that the end of the world is near and there's nothing we can do to stop it. Watch any end-of-the-earth science fiction movie and see how the masses react when told the planet will be destroyed in just a few days.
Before you panic, realize that the Earth is not in danger of falling into the Sun and burning up. But if you want to know what life could be like for your great-grandkids...well, have you ever seen the movie "Waterworld"?
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