Global Temperature Changes example essay topic

GLOBAL WARMING, A FALLACY IN THE MAKING For the last 20 years or so the subject of global warming has spawned heated debate among the world's brightest minds. Its causes and effects, if either actually exists, have been hotly debated. The most popular hypothesis is called the greenhouse effect with the agreed upon cause being green house gasses. These gasses are all naturally occurring and include water vapor, methane, oxygen, and the now infamous carbon dioxide. Greenhouse gasses exist in the atmosphere and have an effect on our global weather.

They trap radiated heat and prevent it from exiting our atmosphere. This supposedly increases global temperatures and is, or will, cause melting of the polar ice caps. This in turn is expected to raise sea level and cause global coastal flooding. A brief geology lesson The world we live on is at least 4.6 billion years old. In that time span it has undergone immense changes. At one time most of the land surface was connected.

The continents separated and migrated to their present positions. The force behind this is called plate tectonics. The sea floor is still spreading today and is the driving force for all of the earthquakes and volcanic activity that we experience today. Convection currents created by the tremendous heat and pressure of the inner core move the plates. This core is undergoing massive thermonuclear reactions. The heat produced migrates outward and the currents it produces move the plates.

This process also releases enormous amounts of carbon dioxide and water vapor. This has been taking place since the Earth was formed. We know from geologic record that there have been numerous greenhouse and icehouse ages. The question is, is the greenhouse state caused by greenhouse gasses? Probably not, at least not entirely.

There are several other factors involved - the most significant being the Milankovitch cycles. These are three cycles that describe the motion of the Earth through space. The first involves the Earth's orbit around the sun. The orbit is not perfectly round, but elliptical. This means that at one point the Earth is closer to the sun than at other times. This cycle takes about 100,000 years to complete.

The second cycle involves the tilt of the Earth's axis. The Earth's axis is currently tilted about 23.5 degrees. But this tilt is not constant. Throughout a period of about 40,000 years the tilt changes a few degrees. This changes the position of the polar ice caps relative to the sun.

The last cycle is called procession of the equinoxes. The easiest analogy is that of a spinning top. The top doesn't spin perfectly round about the axis but wobbles slightly. Again, this process moves the poles closer to, or farther away from, the sun. This cycle takes about 23,000 years. Singularly, none of these cycles seems to have a noticeable effect.

But, when all three work together there is a profound effect. Geologists have been able to find a direct correlation between these cycles and drastic weather extremes, specifically greenhouse and icehouse ages. Back to global warming Now that we know that global temperature changes are a naturally occurring phenomena the question still remains, what about greenhouse gasses? Do they exist?

Of course they do. Do they have an effect on our present weather? Not likely. If anything, they may actually ultimately cause the seas to regress. It's a scientific fact that increased temperatures will increase evaporation. In temperate climates this will mean more tropical weather activity which will release great amounts of heat and energy thus reverting to a cooler climate.

Even if there is melting of the ice caps the increased evaporation will more than offset the melted ice in volume. Increased evaporation means increased rainfall. There is also substantial evidence to suggest that the upper level winds will deposit much of this rainfall over the Polar Regions as snow. Snow has a very high albedo (reflectivity) and direct more sunlight back into space. This has been shown to occur after a large volcanic eruption, which not only expels ash but tremendous amounts of water vapor and carbon dioxide - the two most significant greenhouse gasses! Is the sea rising?

The question still remains, Is the sea rising? The answer is, nobody's sure. Measuring the sea level is a very difficult task. Numerous forces affect the sea. Tides, winds, plate tectonics, and even temperature all affect the data. Since most measuring stations are located along the coast they are subjected to all of these forces.

Cities may subside (sink) under their own weight. While this subsidence is minute, so are the measurements involved with sea level. Remember, sea level changes are measured in hundredths of millimeters per year. As water is heated it expands, further skewing the measurements.

Periods of increased storm activity drastically alter sea level for the entire ocean basin. These measurements must be taken from many locations over a long period of time to have any scientific meaning. Fortunately, the Australian Tidal Facility (NTF) at Flinders University has been compiling such data for an average of 34 years. Their findings came as a surprise to many. They compiled data 1 from 27 different coastal locations. Eleven of these showed a drop in sea level.

The average sea level rise is only 0.16 mm per year. Far lower than even skeptical scientists predicted. Is it getting warmer? For years scientists have been predicting warmer temperatures ahead. Measurements have been taken from nearly every conceivable location. Unfortunately, these results are also flawed.

Most of the readings have to be discarded due to "urban heat-island" effect. Urbanization has greatly affected localized temperatures. The only method to accurately measure the global temperature is to use a satellite based system. This system has been used since 1979. The data collected caught most by surprise. Not only is the Earth not getting warmer, but quite the opposite.

In fact, according to the National Oceanic and Atmospheric Administration (NOAA) climatologist Thomas Karl, in a paper published in 1989, temperatures have been showing a downward trend since their peak in 1940. Satellite readings continue to show a decrease in temperature. They recorded 1997 as the coolest year since this technology has been implemented. This imagery was also accurate enough to predict "that "La Nina" would predominate in 1998, lowering global temperatures significantly'2.

That same year Moscow recorded its coldest December in a century 3. Conclusion This great world of ours has been around for a long time - at least 4.6 billion years. During that time untold and unimaginable changes have taken place. Countless icehouse and greenhouse ages have come and gone. Continents have been created, destroyed, and migrated over and over again.

Thousands, perhaps millions, of species have come and gone. All this, and more, without any influence from man. In geologic terms we have been on this Earth for a very, very short time. The Earth evolves on a time scale that we cannot comprehend. It has developed a balance, a system of checks and balances, which we have little or no control over. To think that we can alter a global climate that has been 4.6 billion years in the making merely shows just how much we have yet to learn.