Milankovitch Mechanisms Of The Pleistocene

Earth has experienced many episodes of dramatic climate changes with different periods in earth history. There have been periods during which the entire planet has been covered in ice and at another time it has been scorchingly hot and dry. In this regards, earth has experienced at least three major periods of long- term frigid climate and ice ages interspersed with periods of warm climate. The last glacial period which current glaciers are the result of it, occurring during the last years of Pleistocene, from approximately 110,000 to 10,000 years age (Clayton, 1997). Indeed, glaciers present sensitive indicators of climate change and global warming and by estimating and monitoring the dynamic evolution of these ice masses, several

The Late Pleistocene period was when the final glacial episode of ice sheets covered much of the northern hemisphere. This event happened about 125,000 years ago and lasted

Ice ages are well documented in Earth’s history, and they are proven to be relatively frequent. But what if that ice age persisted over not just regions near the poles, but around the equator as well? The term “snowball Earth” refers to a condition where Earth is completely covered by ice. Evidence indicates that snowball Earth may have been around in the Neoproterozoic. In fact, evidence points to the conclusion that these conditions happened three separate times in the Neoproterozoic. A snowball Earth condition is hard to prove, but this theory may explain several different phenomena. However, it is not accepted by all, there is evidence against a snowball Earth as well. Some believe that a snowball Earth would not have been possible in past climate conditions while there are views that defend the idea of more of a ‘slushball’ Earth rather than a planet entirely frozen on the surface.

There have been at least five major ice ages in the pass one billion years. The most recent was called the Pleistocene Ice Age, which began about two million years ago. Interglacial periods occurred where temperatures increased slightly and the glaciers would melt and retreat.

Roughly 2.4 million years ago, the Ice Age began on Earth. Over time, the thick snowpack that had accumulated in the Sierra Nevada due to cooled temperatures compacted into giant sheets of ice. These ice sheets became glaciers when they were set into motion due to the pressure of their own weight. The glaciers cleared everything that came in their path including boulders, soil, and trees; everything but the bedrock, which was instead smoothed out, was completely stripped. As global temperatures fluctuated over the years, the glaciers have advanced and retreated multiple

A climate interval from around 1300 to 1750, with beginning and ending dates varying by geography (Wolfe, 2014), the Little Ice Age was a period of time in which mean annual temperatures decreased by about 0.6C and mountain glaciers expanded across the Northern Hemisphere. This period of time occurred after the Medieval Warm Period, around the Middle Ages, and is followed by the current period of warming (Rafferty & Jackson, 2016). This idea of climate cycles—known as Milankovitch cycles—shows that climate change is not a new phenomenon.

Balog was once a skeptic of climate change as he believed that the theory surrounding global warming was based off of computer models. Furthermore, he did not believe that humans could alter the world’s climate on such a global scale. However, through studies of ice records, long tubes of ice drilled from the ground, Balog found key evidence suggesting ideas contrary to his prior beliefs. These glacial tubes preserved historical records of the past similar to the rings of a tree, recording past temperatures and CO2 levels. Using these records, one can see the direct variation between temperature and CO2. Additionally, the recent spike in both

Throughout history climates have drastically changed. There have been shifts from warm climates to the Ice Ages (Cunningham & Cunningham, 2009, p.204). Evidence suggests there have been at least a dozen abrupt climate changes throughout the history of the earth. There are a few suspected reasons for these past climate changes. One reason may be that asteroids hitting the earth and volcanic eruptions caused some of them. A further assumption is that 22-year solar magnetic cycles and 11-year sunspot cycles played a part in the changes. A further possibility is that a regular shifting in the angle of the moon orbiting earth causing changing tides and atmospheric circulation affects the global climate (Cunningham & Cunningham, 2009,

According to the geological and paleontological evidence gained from iron formation, paleomagnetism, and cap carbonates, the globe went through a period of glaciation. The original theory Snowball Earth, proposed that the globe was once covered entirely with ice or snow from poles to the equator. As most of the continental mass was near the equator there was a heightened silicate weathering that resulted in “higher equatorial albedo” and carbon-dioxide “drawdown” which led to global cooling and sea ice expansion (1, 3).

“Following Tertiary time during the Quaternary Period (the most recent 2 to 3 million years) the major sculpturing of Pacific Coastal Alaska began” (Anthony and Tunley 1976). Layers of snow deposited on the high mountains from moisture-laden winds of the Pacific. Over time, the snow compacted into ice; growing into large ice fields, moving, grinding, and carving out the landscape in a flowing movement to the sea. Glaciers advanced and retreated four times during the Quaternary Period (Anthony and Tunley 1976). Nunataks or isolated peaks projecting through ice or snow remained visible during maximum glaciation. “Maximum glaciation provided ice the ability to cap the Pacific Coastal Ranges and extend to the Gulf of Alaska or all the way to the

Science has attempted to clarify completely why an ice age happens like clockwork. As analysts now exhibit in view of a PC recreation, not just do variations in insolation assume a key part, additionally the common impact of glaciated land masses and climate. Ice ages and warm periods have substituted reasonably routinely in Earth's history: Earth's atmosphere cools generally like clockwork, with inconceivable territories of North America, Europe and Asia being covered under thick ice sheets. In the end, the pendulum swings back: it gets hotter and the ice masses melt. While geologists and atmosphere physicists discovered strong proof of this 100,000-year cycle in cold moraines, marine residue and ice, as of not long ago they were not able locate a conceivable clarification for it.

11,700 years ago the geological epoch the Holocene was thought to of began following the Pleistocene epoch, together these time periods make up the Quaternary period. The Holocene has been described as being relatively warm and with a fairly stable climate. Not only this, but it is thought to coincide with the start of agriculture as human populations rose throughout the Holocene technology became more sophisticated aiding the rise of agriculture (Holden, 2012). The early anthropogenic hypothesis was published in 2003 by Professor W.F. Ruddiman, this was a three part hypothesis in which Ruddiman proposed humans reversed natural decreases in CO2 values within the atmosphere by deforestation. That they reversed natural methane decreases after 5,000 years by irrigating rice, they also caused a warming sufficient to prevent a new glaciation within the last several thousand years and during the Holocene (Ruddiman 2005). This hypothesis has attracted a lot of attention with many people both supporting it and criticising it. Throughout this essay I will be exploring the many arguments for and against the early anthropogenic hypothesis and stating whether or not human kind could have prevented the start of an ice age during the Holocene.

The Medieval Warm Period (MWP) refers to a relatively warm period lasting from about the 10th to the 14th century.2 However, the initial evidence for the MWP was largely based on data3 gathered from Europe, and more recent analyses indicate that the MWP was not a global phenomenon. A number of reconstructions of millennium-scale global temperatures have indicated that the maximum globally averaged temperature during the MWP was not as extreme as present-day temperatures and that the warming was regional rather than global. Perhaps the most well-known of these is that of Michael Mann and colleagues (Nature, 392, 1998, pg. 779). Their reconstruction produced the so-called “hockey stick” graphic that contributed to this conclusion in the 2001 assessment of the Intergovernmental Panel on Climate Change: “The…'Medieval Warm Period' appear(s) to have limited utility in describing trends in hemispheric or global mean temperature changes in past centuries." The accuracy of the “hockey stick” graphic was widely discussed in the press when the Mann et al. methodology was criticized by McIntyre and McKitrick (Geophys. Res. Lettr, 32, 2005, pg. L03710). Less attention was given to subsequent studies, such as that of Moberg and colleagues (Nature, 433, 2005, pg. 613) and Osborn and Briffa (Science, 311, 2006, pg. 841) that were based on different, independent methodologies but reached conclusions similar to Mann. Observations of melting high altitude glaciers are

In the last 100 years, Earth’s average temperature has risen by 1.4°F. The rising global temperatures have caused changes in weather and climate. Global warming refers to the ongoing rise in the average temperature near Earth’s surface. This is causing a climate change, which refers to any significant change (major change in temperature, precipitation, or wind patterns) in the measures of climate lasting for an extended period of time (several decades or longer). Due to this, it is projected that the temperature will rise from 2 to 11.5°F in the next hundred years (US EPA, 2014). The “drivers,” which are the principal causes making this occur, are very controversial. It is debated whether a change in temperature is due to the work of

Scientists have discovered 'climate forcing’s ' influence variations in climate systems and based on the depth and period of such forcing’s the adjustments to climate may be in a shorter or longer earth cycle. Natural forcing’s like variations in earth 's orbit, solar variation, volcanic eruptions and motion of tectonic plates have influence on the Earth 's climate