Use of pollen (Polyanalysis)
Pollen analysis is used to assess variability in climate change over the years. This is because it has inherent qualities of rarely rotting. Also, concentrations from different species can be assessed to give an idea of the environmental changes that would have occured. In the graphs, there is evidence of pollen concentration declining over the years for all the species; along with a cumulative reduction. This was seen across all the catchment vegetations or climatic conditions. For example, for Cypernaceae, Rumex and Artemisia, the concentration in the Woodland (open grassland) was at 50%, 40% and 30% respectively between around 428 and 455 ka. This showed a decline in vegetation over time which resulted in climate changes. This could also be interpreted to represent periods during which the early Halocene was unstable. Vegetation that yields pollen thrives in matching conditions but declined when the conditions were unstable or variant.
Stable isotopes
Stable isotopes are used to assess the variability in the glaciers over the years as a result of changes in climatic events. This is possible because δ18O s is affected by water temperatures in the oceans, glacial activities such as erosion and evaporation (Noon, Leng& Jones, 2003). They are also sensitive to soil temperatures, thus their use as a paleoclimatic proxy. The ratio between the molecules of the oxygen atom is used to study the changes in the climate of a particular place.
In the graph, the ratio of the two was uniform during early years but then disparities at around 455 and 490 ka are seen. At point B, the variation was highest, signifying the loss of temperatures at the place. The decline in temperatures causes the concentration of δ18O in lake water or precipitation to decline.
Chironomids
Chironomids are also used for temperature reconstruction and studying other environmental conditions of a place dating back to past years. It works on the basis of pH changes, whereby fluctuations can be inferred for certain changes in the environment. Chironomid has been used variously in climate change studies though with differing conclusions on its interpretations and validity especially when the glacial age ended.
In the graph, the increase in taxa especially in the Tundra lakes at around 10000 BP and at the same time showed that there was decline in cold-water taxa. The trend continued to around 6000 yr BP when Chironomid increased in cold water.
Question 2
Chronology for the lake sediment core can be studied using high performance liquid chromatography (HPLC) dating method. It is more effective than radiocarbon dating and as good as 14C in determining the chronology of lake sediments. The method employed uses lignin phenols that are isolated from the lake sediments. The usual method, radiocarbon dating is not effective in that it assimilates ancient dissolved inorganic carbon (DIC), thus making it ineffective (Ball ,Xu , McNichol&Lihini , 2011). The proposed approach works by separating lignin pigments from old lake core sediments by using reverse phase high performance liquid chromatography. It renders the lake core sediments to be younger and of accurate age as compared to the old radiocarbon method. The latter would make the lake or the age of the lake to be much older than it should be. It is also accurate in that it does not accumulate all the carbon but rather gives individual dating of the cores and hence the correct age. The approach is also compatible with the varve macrofossil dated sediment that is known to be accurate.
Question 3
There is evidence that the temperatures from the two regions is increasing from the data that is given in the graph. Assessing the trend of the two graphs reveals striking semblance that allude to similar causative agents that caused the behaviour. At the GIN Seas, both trend lines show similar pattern that is linked to the GRIP in which Ice core years 11.5 and 12.7 show reduced concentration of the δ18O isotope. This lowers the concentration in the temperature, resulting from the decrease in temperatures. The same is seen in GIN Seas where between ages 10 to around 11.4, the temperatures reduce. The years are related and the trend has a similar trend, showing that the factors that were responsible for the behaviour were similar and affected the two areas at roughly the same time.
Besides, the behaviour of the graph of δ18O concentration at ice core years 12.7 and 13.9 showed a fairly stabilised concentration or temperatures. The same pattern is seen at GIN Seas where between 11900 and 13000, there is fairlystable, oscillating between 40C and 60C. These similarities could be as a result of circulating atmospheric air or just other factor that caused synchronous environmental and climatic change as presented.
Question 4
The changes in the concentration of pollen train are due to the variation of the number of trees that produce the pollen. Pollen does not rot easily and concentration of pollen is indicative of the environmental conditions that disfavoured the survival of tree survival in certain climatic conditions and vegetation zones. Increase in temperatures favoured the survival of Grassland whereas in the in Tundra, the species there declined, hence decreasing pollen grain concentration.
In the second scenario, the graph of δ18O concentration is a proxy for precipitation quantities and atmospheric temperatures. The two isotopes of oxygen and carbon have opposite effects in concentrating in precipitation. At point A, decrease in concentration showed that the temperatures declined, which was similar to point B. The temperatures reached the lowest point while they remained fairly stable at point C though they were still low. Point D marked the highest point reached before the temperatures took a long decline until 385 BP.
The mechanism, by which Chironomid behaved, as shown in the graph, is due to the amount of sunlight exposure, where more sunlight caused the taxa to thrive and vice-versa. This was seen in the warm water in which the % of taxa declined in the Tundra climate but at the same time, those favouring cold weather conditions blossomed. However, from 455 to around 500BP, the trend line showed a similarity of variations in the climatic conditions.
The period 395 and 420 was significant, affecting most of the proxies that were used. It is the period when the lowest pollen grain concentration was recorded and also for highest δ18O concentration. Warm water taxa were also in the lowest concentration at this point. This shows a general increase in temperatures during this period or when the glacier was at the thinnest, hence leading to higher temperatures. Solarradiation was also more intense during this time. After this period, the graphs vary and show a more uniformed pattern, depending on the proxy. The highest temperatures can be said to have been recorded in 425 and 455 BP. The vegetation in the warm water chironomidswas also found to be at the highest level.
Conclusion
Efficient market hypothesis plays a very crucial role in determining the value of the company securities. There tends to be a relationship between the publicly information available and the value of the securities. However, there are other factors that determine the value of the securities. Minimization of risk in the financial market can be through portfolio management. This involves investing in different types of securities. The securities have different returns thereby minimizing risk(Steven L. Emanuel, 2009, p. 256).
References
Earth Observatory: Paleoclimatology, the Oxygen balance,
http://earthobservatory.nasa.gov/Features/Paleoclimatology_OxygenBalance/
Ball G I, Xu L, McNichol A P., Lihini I. (2011) “Radiocarbon Dating of Individual Lignin Phenols: A New Approach for Establishing
Chronology of Late Quaternary Lake Sediments” Journal of Chromatography. 82 (17), pp 7119–712
Noon,P.E., Leng,M.J., Jones,V.J. (2003). “Oxygen-isotope evidence of Holocene hydrological changes at Signy Island, maritime
Antarctica”. 53. The Holocene 13(2), 251-263.
