What Motion Changes Take Place During Milankovitch Cycles
To understand the relationship between the Earth’s journey around the Sun and natural climate change, we must first establish if the amount of solar energy the Earth receives from the Sun is constant or varies over time. Since the Sun is the principal source of the radiant energy the Earth receives from space, it is useful to know if the solar energy flux or solar irradiance, the amount of energy arriving per unit time, varies and if so, then to what degree, in what way, and over what timescales (e.g., are there specific periods or cycles of variation at least over timescales since the rise of human civilization).
The small changes set in motion by Milankovitch cycles operate separately and together to influence Earth’s climate over very long timespans, leading to larger changes in our climate over tens of thousands to hundreds of thousands of years. Milankovitch combined the cycles to create a comprehensive mathematical model for calculating differences in solar radiation at various Earth latitudes along with corresponding surface temperatures. The model is sort of like a climate time machine: it can be run backward and forward to examine past and future climate conditions. Milankovitch assumed changes in radiation at some latitudes and in some seasons are more important than others to the growth and retreat of ice sheets. In addition, it was his belief that obliquity was the most important of the three cycles for climate, because it affects the amount of insolation in Earth’s northern high-latitude regions during summer (the relative role of precession versus obliquity is still a matter of scientific study). He calculated that Ice Ages occur approximately every 41,000 years. Subsequent research confirms that they did occur at 41,000-year intervals between one and three million years ago. But about 800,000 years ago, the cycle of Ice Ages lengthened to 100,000 years, matching Earth’s eccentricity cycle. While various theories have been proposed to explain this transition, scientists do not yet have a clear answer. Milankovitch’s work was supported by other researchers of his time, and he authored numerous publications on his hypothesis. But it wasn’t until about 10 years after his death in 1958 that the global science community began to take serious notice of his theory. In 1976, a study in the journal Science by Hays et al. using deep-sea sediment cores found that Milankovitch cycles correspond with periods of major climate change over the past 450,000 years, with Ice Ages occurring when Earth was undergoing different stages of orbital variation.
Natural causes of Global warming include Solar Output, Milankovitch Cycles, Water Vapor, Volcanic Eruptions and Green House Gases produced naturally. Solar output pertains to the amount of solar radiation that reaches atmosphere and it varies over the cycles of 11 years. The amount of radiations when increased result in global warming. According to some evidences it has increased by .12 watts per square meter since 1750 (Brennan & Media 2012). Milankovtich Cycles refers to the phenomenon of change or variance in position of Earth with respect to sun due to changes in Earth’s orbit. Theses cycles though have very low short-term impact when it comes to climate change. Water vapor is the most abundant natural Green House Gas. Increase in water vapor concentration could/ does have significant effect on the process of Global warming. Volcanic eruptions emit CO2 when they erupt and hence they are responsible for Global warming though in a very small manner. Moreover, there are other Green House Gases like Methane, which are created naturally and also contribute to the problem of global warming. Onthe other hand, the primary cause of global warming by humans is due to the carbon dioxide released when fossil fuels like oil and coal are burned for energy (ygoy 2012). Wide scale industrialization and technological advancements has contributed massively to the cause of Global warming. All forms of transport, which consume one or the other forms of fossil fuels, are culprits too. Increase in population and Deforestation have increased the CO2 emissions to exaggerate an already serious issue. Chiefly, the close examination on comparison of both natural and human causes of global warming clearly put the main share of blame on human causes. According to study by European scientists, the natural cosmic ray or solar irradiance contribute less than 14% to global warming (Statsburg 2009).
In conclusion since 1750, the warming driven by greenhouse gases coming from the human burning of fossil fuels is over 50 times greater than the slight extra warming coming from the Sun itself over that same time interval. If Earth’s current warming was due to the Sun, scientists say we should expect temperatures in both the lower atmosphere (troposphere) and the next layer of the atmosphere, the stratosphere, to warm. Instead, observations from balloons and satellites show Earth’s surface and lower atmosphere have warmed but the stratosphere has cooled. Finally, Earth is currently in an interglacial period (a period of milder climate between Ice Ages). If there were no human influences on climate, scientists say Earth’s current orbital positions within the Milankovitch cycles predict our planet should be cooling, not warming, continuing a long-term cooling trend that began 6,000 years ago.
Brennan John, Media Demand. ”Natural and Non-Human activities that impact global warming” National Geographic. 20 April 2013. Web. 2012
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Spencer, Roy. ”Global Warming” drroyspencer. 20 April 2013. Web. 2010
Ygoy. ”Human causes of global warming” YGOY. 20 April 2013. Web. 2012