Climate Change - Man or Nature free essay sample

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 Earths 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. Its reasonable to assume that changes in the suns 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 Earths orbit around the Sun. The orbit gradually changes from being elliptical t o nearly circular and then back to elliptical in a period of about 100,000 years. â€Å"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 Earths 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 following illustration, the Earth is closer to the Sun in January and farther away in July at the present time. Because of precession, the reverse will be true in 13,0 00 years and the Earth will then be closer to the Sun in July (illustration B). This means, of course, that if everything else remains constant, 13,000 years from now seasonal variations in the Northern Hemisphere should be greater than at present (colder winters and warmer summers) because of the closer proximity of the Earth to the Sun† (Pidwirny, 2006). [pic] The tilt of the Earth axis of rotation cycles approximately every 41,000 years (physicalgeography. net, 2012). The results from a changing tilt are somewhat counter intuitive. With a slight tilt, the climate has less variability and winters are milder and summers cooler. Milder winters actually result in more snow and ice accumulation and not less. This effect is due to the capacity of warmer air to hold more water vapor and thus increase the snowfall that occurs. Cooler summers promote slower melt cycles and thus glacial ice can accumulate. The converse effect is when the tilt is at its maximum and winters are significantly colder and summers hotter. These factors combine to produce less snow – cold temperatures equal less contained moisture in the air, and the hotter summers produce greater melt cycles. â€Å"Computer models and historical evidence suggest that the Milankovitch cycles exert their greatest cooling and warming influence when the troughs and peaks of all three cycles coincide with each other† (Pidwirny, 2006). Atmospheric gases are a major component of the system that regulates the planet temperature. The emission, dissipation, and adsorption of these gases affects and is affected by the internal (within the planet) and external (extraterrestrial) activities that alter the levels of these gases. A layer of gases in the atmosphere – called greenhouse gases for their ability to trap some of the infrared heat energy that is reflected on Earth’s surface is composed primarily of water vapor, and including much smaller amounts of carbon dioxide, methane, nitrous oxide, and sulfur dioxide. Of all the gases in Earth’s atmosphere, water vapor is the most important component. Water vapor is the most abundant greenhouse gas and contributes the largest amount of insulating effects for maintaining the life sustaining average temperature of 59 degrees F. Through the water cycle, it acts as a feedback to the climate. As water vapor increases in the atmosphere clouds form and promote the recycling of water in the form precipitation. The water cycle of evaporation, condensation, and precipitation provide a critical feedback mechanism to the greenhouse effect. Although an excess of greenhouse gas results in global warming, naturally occurring greenhouse gases are beneficial in keeping our planet at a comfortable temperature† (National Oceanic and Atmospheric Administration, 2012). The gas causing the greatest concern over global climate change and the current warming trend is carbon dioxide. Though much less prevalent than water vapor, carbon dioxide also has feedbac k system to respond to forces that alter its concentration. Carbon dioxide is part of the natural carbon cycle where â€Å"billions of tons of atmospheric CO2 are removed from the atmosphere by oceans and growing plants, also known as ‘sinks,’ and are emitted back into the atmosphere annually through natural processes also known as ‘sources. ’ When in balance, the total carbon dioxide emissions and removals from the entire carbon cycle are roughly equal† (EPA. gov, 2012). â€Å"In the geological history of the Earth, carbon has been cycling among large reservoirs in the land (including plants and fossil fuels), oceans, and the atmosphere† (Pidwirny, 2006). The planet’s oceans are the largest sink of carbon dioxide. Carbon dioxide is soluble in water, but the solubility or amount of CO2 that can be stored in the oceans- is temperature dependent. Think of a carbonated beverage. Trapped CO2 diffuses through the liquid and escapes leaving the surface as tiny bubbles. If you warm the liquid, the CO2 escapes much more rapidly. This demonstrates the temperature dependent function of solubility. â€Å"Initial changes in global temperature were triggered by changes in received solar radiation by the Earth through the Milankovitch cycles. The increase in carbon dioxide then amplified the global warming by enhancing the greenhouse effect†. This demonstrates that naturally elevated CO2 levels are a result of global warming and not a cause of it. Another source of natural climate change is the dynamic variability of all the forces that affect Earth’s atmosphere. â€Å"Perhaps the most well understood occurrence of climate variability is the naturally occurring phenomenon known as the El Nino-Southern Oscillation (ENSO), an interaction between the ocean and the atmosphere over the tropical Pacific Ocean that has important consequences for weather around the globe. The ENSO cycle is characterized by coherent and strong variations in sea-surface temperatures, rainfall, air pressure, and atmospheric circulation across the equatorial Pacific. El Nino refers to the warm phase of the cycle, in which above-average sea-surface temperatures develop across the east-central tropical Pacific. La Nina is the cold phase of the ENSO cycle. The swings of the ENSO cycle typically occur on a time scale of a few years. â€Å"These changes in tropical rainfall affect weather patterns throughout the world† (National Oceanic and Atmospheric Administration, 2012). A strong and awesome contributing to the climate are volcanoes and their short term cooling effects followed by longer periods of insulating effects. The argument against volcanoes contributing to global warming is mostly due to the solar radiation reflecting effects of atmospheric aerosols formed from sulfur-dioxide (a major component of volcanic gases). The sulfur dioxide compounds form a protective shield that reduces the amount of solar energy that impacts the earth and thus, for a brief period, the planet cools. This argument is both short-term focused and limited in its understanding of molecular heat capacity. For a deeper understanding, let’s evaluate the nature of sulfur dioxide and its climate changing effects. â€Å"SO2 is a tri-atomic, non-linear, asymmetric-top molecule with a permanent dipole moment very similar to ozone (O3) but very different from CO2, a linear molecule without a dipole moment. SO2 has an absorption intensity two orders of magnitude greater than ozone in the near ultraviolet spectrum (350-400 nanometers) where the atmosphere is normally transparent to solar energy. Photons at these wavelengths contain 43 times more energy than infrared photons absorbed most significantly by CO2. These high energy photons cause electronic transitions that are much more effective at increasing the kinetic energy and thus the temperature of the atmosphere† (Ward, 2009). According to detailed and documented research of Dr. Peter Langdon Ward and supported by any modern geo-physical chemical textbook: SO2 in the troposphere appears to cause greater warming than four orders of magnitude greater concentrations of CO2. Between 1979 and 2000, humans decreased SO2 emissions 18% in an effort to reduce acid rain. The rate of increase in global temperatures and concentrations of methane decreased to zero by 1998. Temperatures have been relatively constant for 12 years while concentrations of CO2 have continued to rise at a constant rate. Clearly global mean surface temperatures are not a direct function of CO2 concentrations as is assumed in most atmospheric models. As SO2 concentrations decreased, hydroxyl radical (OH) concentrations increased, oxidizing methane, causing methane concentrations to stop increasing. This implies that the increase in methane concentrations during the 20th century may have been caused by increasing amounts of SO2 emissions decreasing the oxidizing capacity of the atmosphere rather than increased emissions of methane. During the 20th century, humans burning fossil fuels warmed the lower atmosphere and therefore the ocean ~0. 8oC, resetting the thermostat for the earth. There is no proven way to cool the ocean similar amounts within decades. Continued melting of ice and snow, most notably in the Arctic is the result of the ocean and atmosphere slowly approaching equilibrium after this sudden change in the earths thermostat. Solar intensity decreased (global dimming) in response to increasing SO2 and decreased (global brightening) in response to decreasing SO2. SO2 absorption is greater in polar regions due to increased length of the paths of photons within the atmosphere. This fact helps explain why temperature increases have been so much greater, especially in the Arctic where Arctic haze increased with increasing SO2 emissions. Only when the effects of solar-energy absorbing gases such as SO2 are built into climate models, will it be possible to determine the effects of the prodigious anthropogenic emissions of CO2 in the past or in the future. Ward, 2009) It is the premise of science to test and verify before publishing hypotheses. So much of the so-called consensus studies reach conclusions drawn from an incomplete model. Consensus is not a scientific parameter. The ability to question what has been presented before is one of the marks of keen research. There is a large component of atmospheric gase s that mankind’s activities have significantly impacted to be sure. To conclude that it is these activities and increases in carbon dioxide emissions alone, is folly and extremely short sighted. Man can not control the natural forces that impact global climate change. We can however study all the factors in their entirety and adjust our activities to minimize their impact. The natural causative forces play a much greater role than is being considered in the current politically charged and funded debate. Let’s approach the issue with an open mind and recognize that nature is more powerful than given credit for when it comes to global warming. Man has a responsibility to mitigate modern practices so that nature can equilibrate and we can all cool off and catch our breath.