Global Climate Change –
Is climate change a natural phenomenon or caused by man?
There has been some discussion and debate over the causes of global climate change and particularly, the causative forces that have contributed to the measured increase in the mean atmospheric temperature over the last several decades. Many researchers and climatologists have concluded, using climate modeling systems that the main cause is anthropogenic (man caused). Other researchers have argued that the model is ineffective and biased due to short-term horizon values and that the causes of increased temperatures are due to the natural cycles of the planet. It is my belief that both nature and man contribute to climate change. Mankind’s impact, however, has been much more pronounced of late. As a trained scientist and chemist, I prefer to demonstrate the natural causes and contributors to climate change rather than asserting that climate change is exclusively the result of one or the other climate force. The natural causative agents that promote global climate change are many and the complex systems that provide for and regulate our natural environment are not static. That is – they are in a constant series of cycles that create, adapt, and react to climate changes. The many natural factors affecting the climate can combine to amplify the effects of the others or to counteract them. The contributing forces that alter our climatic system are illustrated in the following diagram: [pic] (Pidwirny, 2006)
“The work of climatologists has found evidence to suggest that only a limited number of factors are primarily responsible for most of the past episodes of climate change on the Earth” (Pidwirny, 2006). These factors when at there maximum or minimum values have significant impact on Earth’s overall climate. . Factors affecting climatological changes include:
• Natural changes in the Earth's orbital characteristics. • Atmospheric gas composition variations.
• Volcanic eruptions
• Variations in solar output and absorption by the planet. These climate forces will be identified and evaluated as factors contributing to global climate change.
According to a theory presented by Milutin Milankovitch, changes in the Earth’s climate are caused by varying three geometric relationships between the Earth and the Sun (physicalgeography.net, 2012). The physical (spatial) relationship between celestial bodies cycles over time in repeated phases of orbital patterns. The main changes that occur in the eccentricity (shape or roundness of orbital path), precession of the equinox, and obliquity (tilt) of the Earth, cause cyclical variations in the location, timing, and intensity of solar radiation. “It's reasonable to assume that changes in the sun's energy output would cause the climate to change, since the sun is the fundamental source of energy that drives our climate…. studies show that solar variability has played a role in past climate changes” (NASA.gov, 2012). http://climate.nasa.gov/causes/
Eccentricity measures the shape of the Earth's orbit around the Sun. The orbit gradually changes from being elliptical to nearly circular and then back to elliptical in a period of about 100,000 years. “The greater the eccentricity of the orbit (i.e., the more elliptical it is), the greater the variation in solar energy received at the top of the atmosphere between the Earth's closest and farthest approach to the Sun” (Pidwirny, 2006).
The precession of the equinox alters the angle of incidence – measured angle of impact between the Sun’s rays and the Earth, affects the strength of solar radiation. At low angles, the majority of radiation is reflected off the atmosphere much like skipping a stone over water. When the suns rays are perpendicular to the planet – the radiation transmittance is at its maximum intensity. “The precession of the equinox has a cycle of approximately 26,000 years. According to the...