Climate Change and General Crisis Term Paper
- Length: 10 pages
- Sources: 10
- Subject: Weather
- Type: Term Paper
- Paper: #42384864
Excerpt from Term Paper :
Geomorphologic evidence of glacier fluctuations in Iceland during the Late Holocene is abundant. Furthermore, Iceland has a unique documentary record of ice-front positions between the times of settlement, around AD 870, to the early 20th century. Many of Iceland's larger outlet glaciers have been systematically monitored since 1930. Consequently, a general description of glacier conditions exists for the past/1000 years, in addition to a detailed knowledge of ice-front fluctuations for the past 70 years. Consequently, the idea of a broadly synchronous late 19th-century glacier maximum in Iceland has been widely accepted (Bradwell, Dugmore, & Sugden, 2006)
The difficulty in specifying the timing of the LIA is because the coldest period in the last 1,000 years was not uniformly cold. Furthermore, the occurrence of cold events around the globe was not synchronous and thus spatial differences exist. For example, the seventeenth century was the coldest LIA period in eastern Asia, while in Europe the nineteenth century was the coldest period of the LIA. Even on the regional scale, there are differences. In the late 1700s, the Czech Republic experienced a warm period, but the Low Countries underwent a cooling. However, a few cool periods may have been synchronous on a hemispheric scale, and some even on a global scale. An additional difficulty in establishing the period for the LIA is that the different seasons do not necessarily show temperature anomalies of the same sign over time. For instance, between 1750 and 1800 the winter temperature anomalies in Switzerland show a cooling, while the summer temperature anomalies show a warming. Several model studies have investigated the forcing, which could have caused the LIA and have assessed the impact of the forcing on different components of the climate system. Researchers showed, using simple energy-balance models, that volcanic and solar forcing is important for a realistic simulation of the LIA. Furthermore, they concluded that greenhouse gas changes need to be taken into account to simulate the warming over the twentieth century (Sedla'c-ek & Mysak, 2009)
Another area affected by LIA is the Greenland Ice Sheet in the Kangerlussuaq area of west Greenland that is a relatively stable passive ice margin with small outlet glaciers. Throughout southern Greenland, abundant evidence in the form of fresh erosion features and erratics on islands and coastal hills indicates that ice in the last glaciations covered most of the present un-glaciated land area and extended onto the continental shelf. The bottom sediments on the banks of the shelf are sands and gravels with coarse clasts typical of glacial or glaciomarine facies. Moraine systems have not been positively identified, although geophysical surveys have shown their presence on the West Greenland shelf to the north. Despite this, the outer parts of the banks are generally considered to correspond to the limit of the last glaciations. While that can be crudely correlated with the Last Glacial Maximum (LGM), the history of glaciations of the shelf is likely to have been long and complex. Some confirmation of a shelf-break location of the ice-sheet margin at the LGM comes from the modeling of the relative sea-level curve for the southern sector. The model requires this marginal position as well as the existence of a 1500-m-thick ice cover over the outer coast, completely covering the coastal mountains. However, the isostatic loading is based only on a local South Greenland ice cover (Weidick, Anker, Kelly, & Ole Bennike, 2004)
Suspected Causes of the Little Ice Age
Syszygyastro (n.d., p. 1) went on to discuss suspected causes of the LIA. It was stated that LIA could have been caused by:
A) Asteroid or comet impacts
B) cooling of the sun - sunspot minima
C) drying cycles where lots of dust gets into the atmosphere
D) increased albedo of the Earth
E) Mid Atlantic conveyor shut down
F) Mankind's industrial and warlike activities
The causes behind the Little Ice Age, whether global in extent or not, are not well understood. Three climate change mechanisms that operate on century time scales have been considered, volcanic eruptions, variations in solar energy, and changes in ocean circulation, although none of these on their own seem to reliably predict the observed climate changes throughout the Little Ice Age. More probably, a combination of these and other climate forcing processes has together influenced the climates of the last 1,000 years. ("Little Ice Age," 2010, p. 1)
There are several ideas as to what may have triggered The LIA. First among these hypothesis is seen in the context of larger 100,000-year cycles, the Earth should be heading into a prolonged ice age as indicated by patterns found in ice cores extending back 800,000 years covering an eight full cycles of roughly 100,000 years each. The last warming meltdown occurred some 12,600 years ago and by now, we should be in a cooling trend covering 90,000 years. However, modern industrial processes have stopped and reversed the trend. Second among the ideas of cooling is the dynamics of the Earth's orbit. Currently, the perihelion of the Earth's orbit falls on January 5th, plus or minus a day depending on Earth's orbital speed due primarily to the influences of Venus and Jupiter and their locations relative to the Earth and Sun. This puts Earth closest to the sun on or about January 5th, during the northern hemisphere's winter. By June-July, the Earth is furthest from the sun. This has the effect of slightly cooling the global temperature in this period considered the LIA (Syszygyastro, n.d., p. 1).
Effects of the Little Ice Age
Gardiner (2008) expresses that the little ice age is not considered a true ice age because it did not get cold enough for long enough to cause ice sheets to grow larger. The cooling more than likely affected areas around the world but the place most documented by this researcher was the occurrence in Europe. This researcher went further to explain things that were affected by the little ice age. They included (para. 4):
Fur trappers reported that southern Hudson Bay remained frozen for about 3 weeks longer each spring.
Fishermen reported large amounts of sea ice floating in the North Atlantic.
British people saw Eskimos paddling canoes off the coast of England.
Alpine (mountain) glaciers grew larger. In some cases, the ice engulfed mountain villages.
Winters were longer and growing seasons shorter according to tree ring data and records of cherry tree flowering.
Wet weather caused disease that affected people, animals, and crops including the bubonic plague (also called the Black Death). This disease killed more than a third of Europeans.
Farms and villages in Northern Europe were deserted because the farmers could not grow crops in the cooler climate. During the harshest winters, bread had to be made from the bark of trees because grains would no longer grow.
Limited crops and unhealthy livestock caused famine in areas of northern and Eastern Europe. Unlike today, there was no way to transport food around the world to areas where crops had failed and people were hungry.
Syszygyastro reported that after the LIA, farming communities collapsed and the settlers either withdrew or perished in famines leaving the country to the Inuit and Eskimos who had long since adapted to the harsher. The weather patterns also shifted in Europe, bringing a lot of rain and this general pattern continued until the 19th century. There period between 1600 and 1850 was the most stable. From 1250 through to 1600, there were brief warm spells, but these were not the normal trend of deep long cold winters and brief hot summers (n.d., p. 1).
Grove (1988) added that due to LIA, sea ice and stormier seas made the passage between Norway, Iceland, and Greenland more difficult after AD 1200. Life in Greenland became harder; the people were cut off from Iceland and eventually disappeared from history towards the end of the fifteenth century. Grain would no longer ripen in Iceland, first in the north and later in the south and east. As the northern winters became colder, fish migrations took different tracks and life became tougher for fishermen as well as for farmers. In addition, unfruitful harvests were experienced in the latter part of the 13th century and in the early 14th century as well as famine in England. LIA cause extreme swings in the weather i.e. colder winters and hotter summers.
Research indicates not only that there is still question regarding the dates of the LIA, it is also evident of the impact the LIA, had even though most researchers state that the effect was not impactful enough to be considered a true ice age. Landscapes were forever changed i.e. Iceland etc. On the other hand, there are those that believe that the LIA was created by man in a way. Through a greenhouse effect, that man caused these shifts in weather that ultimately caused the LIA to occur.
It is evident through the compilation of data in this current research; there is…