Last Glacial Maximum

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

Increasing greenhouse gas concentrations are expected to have significant impacts on the world?s climate on a timescale of decades to centuries. Evidence from long-term monitoring studies is now accumulating suggests that the climate of the past few decades is anomalous compared with

Scientists have given numerous warnings that human-caused, or anthropogenic, climate change is not only occurring now, but accelerating more quickly than predicted (Maibach, Myers, and Leiserowitz 295). Global warming contributes to climate change as a result of the release of greenhouse gases into the atmosphere (“Global Warming”). The level of greenhouse gases like carbon dioxide, methane, and nitrous oxide in the atmosphere has increased significantly over the years. Patterns of warming are sufficient to conclude that this increase has coincided with the start of the Industrial Revolution (“Global Warming”). By analyzing carbon dioxide pockets that have been trapped in Antarctic ice, scientists can assuredly confirm the correlation between recent warming

The passage declares numerus reasons in hope of justifying the real causes of Little Ice Age existence during 1350 till 1900 CE. On the contrary, the lecture challenges all the aforementioned theories by passage and believes inasmuch as the outdated information used by passage all those clarifications are merely sheer implausible misconceptions. In what follows, three major hypotheses and their critics will be delved into nut briefly.

The Earth 's atmosphere has changed all through history. Just in the most recent 650,000 years there have been seven cycles of frigid progress and withdraw, with the sudden end of the last ice age around 7,000 years back denoting the start of the present day atmosphere period and of human development. The greater part of these atmosphere changes are credited to little varieties in Earth 's circle that change the measure of sun based vitality our planet gets. Exploratory proof for warming of the atmosphere framework is unequivocal. The present warming pattern is of specific criticalness in light of the fact that the vast majority of it is likely human-impelled and continuing at a rate that is exceptional in the previous 1,300 years. Earth-circling satellites and other mechanical advances have empowered researchers to see the comprehensive view, gathering a wide range of sorts of data about our planet and its atmosphere on a worldwide scale. This group of information, gathered over numerous years, uncovers the signs of an evolving atmosphere. The warmth catching nature of carbon dioxide and different gasses was shown in the mid-nineteenth century. Their capacity to influence the exchange of infrared vitality through the environment is the logical premise of numerous instruments flown by NASA. There is no doubt that expanded levels of nursery gasses must bring about the Earth to warm accordingly. Ice centers drawn from Greenland, Antarctica, and tropical mountain icy masses

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,

If you have ever heard of the Last Glacial Period, you would know that it covered majority of Canada and northern US in a thick blanket of glaciers. When the Last Glacial Period ended and all of the glaciers retracted, it scraped away vast amount of soil and minerals from certain areas of Canada, leaving some areas with rich and fertile soil suitable for farming due to deposits from the ice. However, in other regions such as the Canadian Shield, were left scarred with very thin soil that is no longer sufficient for agriculture. When travelling through the area, I had expected to see a desert created from the desertification of the thin layers of soil. To my surprise, vast amount of trees grow here in the southern parts of the Canadian Shield!

The true impact of “The Little Ice Age” began around 1600 and lasted until the 1800’s. During that time in Europe is when it was at its height. It was considered to be the most significant climate event of the last millennium. Only until recently have climatologist discovered research of climate conditions in historical times. As stated before, no one is quite sure how “The Little Ice Age” evolved. Climatologist and historians have had many discussions on what they think was the main cause of the ice age. Today they are able to determine the yearly average temperatures, rainfalls, volcanic activity, and the effect of the sun during that period . What we know is that the sun experienced a “quiet” period, meaning its intensity was not that strong. Therefore, a cooling occurred. Sunspots which determine the suns strength were noted to be in decline. Volcanic activity is to be another known source of the cause. As the volcanoes erupted they shot out particles and gases into the air. With these gases floating in the

The last glacial period has encountered numerous large-magnitude, rapid climate change events; characterising the period between 10ka and 50ka (Steig, 1999). During this period was the Last Glacial Maximum (LGM), which occurred approximately 21ka, a glacial period defined by changes in greenhouse gases, sea level and ice sheets (Otto-Bliesner et al., 2006). In comparison the mid-Holocene occurred approximately 6000 years ago, during the current interglacial. The Holocene period is regarded as relatively muted in terms of ‘signals’ of climate change, with changes primarily associated with changes in seasonal solar radiance (Otto-Bliesner et al., 2006; Steig, 1999).

The Milankovitch Mechanisms are central to long-term climate history discourse (Berger, 2013) and incorporate three orbital changes, which are named Precession, Eccentricity and Obliquity. Eccentricity is the first Milankovitch Mechanism, whereby the orbit of the Earth around the sun varies from a nearly perfect circular shape to a more elliptical shape (Figure 1A). At its most elliptical orbit, the Earth passes ~6 million miles (Scofield, n.d) further from the sun at the point of aphelion, and subsequently, the winter climate would be extremely cooler due to the reduction in incoming solar radiation. With Eccentricity, the insolation received can change by ~30% (Maslin and Ridgwell, 2005) and occurs at cycles of ~100,000 years (Maslin and Ridgwell, 2005). Obliquity is the second Milankovitch

First we will address results about how annual planetary albedo was affected by altering the forcings in the simulations. Overall, when comparing Control Experiment (Modern Specified SST) to Primary Experiment 3 (Ice Age 21kya run), we observed a relatively higher planetary albedo during the Last Glacial Maximum, with an average of 2.37% increase. In areas with known ice sheets, such as the Laurentide Ice Sheet over the upper section of North America or the Scandinavian Ice Sheet over Northern Europe, there was a much more drastic change in albedo. In these regions, the albedo was significantly higher during the LGM, up to 27% higher in certain areas. Albedo was also higher south of the equator in the oceans surrounding the Antarctic. Some parts of the earth had a near-neutral change in planetary albedo, mostly in low latitude areas like the tropics. This can be seen in Figure 1.

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

The report concludes, again with “high confidence”, that anthropogenic (human caused) warming has had a discernible influence on many of our planets physical and biological systems. While there are limitations and gaps in the knowledge available, particularly from undeveloped countries, the knowledge available allowed the group to attribute most of the observed increase in the globally averaged temperature since the mid-20th century to the observed increase in anthropogenic greenhouse gas concentrations. The analysis was necessarily limited in the number of systems and locations considered. In addition, natural temperature variability is larger at the regional than at the global scale, thus affecting identification of changes due to external forcing and at the regional scale other factors such as land-use change and pollution, are an environmental

Figure 1 shows two aspects of the results. The left side displays the information about the amount of greenhouse gases and ozone changes in “500 hPa geopotential height trends (m) are for 1979–2000” (Schindell). The top left shows the computer model predictions while the bottom left shows what existed during the 1979-2000 time frame. The right side of figure 1 shows the “surface air temperature trends (C) are for 1969–2000” (Schindell). Both of these images show the temperatures in the arctic regions are cool and the middle latitude regions are warmer. This is an effect of the changes occurring with the greenhouse and ozone gases.

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