Climatic change in the Holocene era.
Historically, the Holocene era refers to the historical epoch which spans 10000 years down the history of humanity. This is the time which has spanned out from the time when the major glacial activity happened lastly. Accordingly, history has seen various small and large-scale climatic changes which even includes the age of the little ice which occurred between 1200-1700 A.D. However, Holocene has depicted a wide spread of warm climatic conditions occurring between ages of ice periods. The period came after maximum last glacial epoch where various subsequent periods of de-glaciations occurred. Between early period and the mid of the era, parameters of the earth’s orbit had an activity of insulation allowance creating wetter conditions which primarily had warmer temperature conditions when compared to the current situations of the summer periods which occur within the globe’s northern hemisphere. Accordingly, various geological data have provided a broad image of indications which even include the great retreat that has occurred in the ice placed within the Arctic sea, great expansionary phenomena in regard to the boreal forest, alongside the Saharan vegetation dispensation. Elsewhere, the gradual deterioration in the climate within the earth’s northern hemisphere had its interruption by various events that occurred in an abrupt manner. (Sassaman, David, 58)
Historically, greater weather changing epochs has characterized this era. Presumably, a highly pronounced state of cooling occurred in the period between the last 8200 years which led to a pulse of fresh water coming from a lake of melted water across the southern part of Laurentide sheet of ice which led to a temporary dilution in the circulation of Atlantic Ocean. However, the climatic and geological influence across the era has called for diverse study modeling of the palaeoclimate analysis. Among them are the dendrochronology and the pollen core sample techniques. (Sassaman, David, 59)
Elsewhere, the last 10000 years have seen great epochs in the changes that have occurred in the trace atmospheric gases, solar systems and forces, human climatic influences such as deforestation and volcanism above other fundamental climatic autobiographies. In the lieu of the diversity in these epochs, huge bunches of questions have however accompanied these racial developments in relation to developmental outlays that proximate Holocene era. From these effects, various discrepancies have been voted out to the data chronology that describes the diverse climatic phenomena across the board. (Andrew, 1992, 65)
According to the advancements on the climatic studies across the period, many variables and also parameters have characterized the period. Largely, the period has been characterized by a long characteristic development in trends of global temperatures. There has been a changing variability in climatic situation far from the temperatures within the surface of Alkenone Sea of both Arctic and the Antarctic circles that has resulted to a changing climatic phenomenon. (Andrew, 1992, 68) Amongst the eminent historical climatic orientations is the great glaciations period where a situation of an abrupt global warming as well as a moistening situation within the climatic phenomena occurred that explain the great history in global climate. Down the Holocene era, the mid latitudes have been characterized by higher temperatures, with other parts of the globe (poles) acquiring even lower levels of temperature. (Wilson, Drury, 2001, 82)
Assessing the climatic situation, climatic changes have shaped the global condition with great variations into the global temperatures resulting into even global warming. Such high global temperatures however have their historical background from the glaciations period which was historically characterized by low temperatures. Greatly, the medieval period has seen the highest variations which encompass both warm period and an age of little ice. Accordingly, there was the rising of the Medieval Warm Period (MWP) as described within Europe had a warm climatic abnormality which went from the 10th century across the 14th Century. Either, Little Ice Age (LIA) that was characterized by great cooling occurred between mid of 14th century and the 19th century. The same cooling was the main tool which led to change in the warm medieval temperatures. Beginning the 1650, three periods of maxima characterized the earth’s climatic condition. (Wilson, Drury, 2001, 86) In the late ages of the 17th century, meteorological studies provided for measured atmospheric pressure and also temperatures. Since the 20th century, great developments in meteorology have provided a wide scope in climatic studies. Accordingly, various trends in the global atmospheres have been analyzed which has highly helped to study the development in climatic conditions since the Holocene era.
The use of pollen core samples to study the effects and impacts of the climatic changes during the Holocene era is perhaps a great development that would yield insightful conclusions. Generally, the scope of palynology refers to the scientific study in which fossil palynomorphs that include pollen are used in studying climatic changes. Through pollen core sampling in palynology, the diverse geographical distribution within the broad plant species is studied in its occurrence under the different biographies of climatic dispensation. Scientifically through pollen core sampling, various plant species and varieties have been credited to having their existence in various parts of the globe in response to a wide range varying phenomena in climatic dispensation. Accordingly, the study of pollen core samples have provided that different types and species of plants depict different pollen make up which compromise difference in the distinctive surface texture and also shapes in response to a broad array of climatic biography. (Richard, 2004, 78) However, the resilient outer surface of the pollen material has provided it with adaptive conditions in which it can resist decay from the influence of climatic situations. According to various studies, the sedimentary deposits found in river deltas and also lakes has provided various types and nature of pollen compounds. This has been a scientific characteristic of changing plant chronology across the broad span of the Holocene era. Since the same pollen depicts changes, it is evident that the changes in the plant pollens would only have occurred following changes in the broad global climate. Otherwise, if the climatic situation were constant, the state of pollen deposits as sedimentary rocks in the global sedimentary rocks formation would provide no difference in the pollen stratification. Hence therefore, a constant state of climate would provide for a constant state of pollen deposits. Broadly, pollen analysis has been a major tool in the scientific reconstruction that brings developments in the palaeoclimatic studies. The scientific study of pollen analysis to provide climatic change developments is called palynology. Through pollen core sampling, pollen grains and their spores have been found to accumulate over long periods of time which has depicted changes in the nature of the global vegetation changes over the period of time. (Richard, 2004, 80) Consequently, researches have held that such changes occurring in global vegetation has its main cause from the relative changes in the global climate. Palaeoclimatic construction has therefore been developed from the validated interpretations of the changing autonomy of vegetation through a detailed research and analysis of pollen.
Scientifically, plant pollen grains as well as their spores have been found to have a great resilient resistance to microbial decay with their production been relatively in huge quantities. Elsewhere, their distribution has been found to change considerably with their sources. Through their unique characteristics of plant morphology, various plant species as well as genus have helped in assembling studies about the past vegetative chronology. Accordingly, different plant at different climatic conditions have provided difference in their productive and also the dispersion statuses and rates of their pollen. Consequently, palaeoclimatic reconstruction has provided that deposits of pollen have had a diverse autonomy in regard to changing climatic conditions which have changed the plant biotic characteristics. (Richard, 1997, 45) The inter-species characteristics which have sparred across the past time domain have ratified for a broad spectrum of pollen changes which depict changes in the climate. In a research edition by Davis in 1963, the application of uniformitarian principle has helped to compliment the present phenomena with the past situation. From the current changes in the development of pollen perceived in the modern scientific autonomy, the past should have taken the same periphery. (Richard, 1997, 47)
According to polynology, the basic characteristic of pollen as been aelian which implies the ease of wind blown, sediments of the same have accumulated in various surfaces without physical disturbance. Accordingly, various pollen sediments collected from different depository surfaces such as alluvial deposits, peat bogs, ocean bottoms as well as lakebeds have therefore showed a broad image of changing fossil characteristics due to the changing nature of the depository material (pollen). Such changing characteristics have been allied to the changes in the climatic conditions which have consequently led to change in the plant biology. (Mannion, 1999, 71)
Indeed, pollen core sampling has been a contributory development in learning about the changes in the climatic autonomy within the Holocene era. From the impact of the changing state of climate in the era, plants have changed the biotic characteristics to adapt adequately to the requirements of the changing nature of the global climate. The evidence of the pollen compounds and fossil characteristics from chemical compounds arising from pollen deposits, it is a clear prove that the same has been influenced by the changes in the climatic situations. Elsewhere, since the sedimentary deposits has spanned over a long transcend period of time, the forth while implication of the changing plant biology due to climatic influence would rationally be a development allied to a long period of time. The necessity of the Holocene era has scientifically stood therefore to signify a rational significance as a period of climatic changes that had direct influence on the plant biology. (Brown, 1999, 86)
However, in the accreditation imagery of pollen sampling to studying climatic changes across the Holocene era, many arguments are paused across in trying to use the same method to studying changes in Holocene era. This is from the wide scope of difficulties which have been associated with scientific analysis of such pollen. Hence therefore, such palaeoclimatic reconstructions provide only qualitative developments of significance. Elsewhere, the framework of climatic description have only provided for qualitative attributes such as warmer/colder or elsewhere drier/wetter. However, the same does not provide a reliable quantitative capacity into the characteristics of the climatic conditions for the era. Indeed, the quantification process in the climatic results and implications has only called in use of specific samples of pollen and disregarding the basic assembly of all types of pollen samples. This has been through the choice of specific plant species which have been known to exist in specific situations of climate. These include mistletoe (Viscum), ivy (Hedera) and holly (Ilex). However, the choice of establishing such species has been a rare opportunity where many are extinct above their dispersion been uneven across the earth’s surface. Consequently therefore, use of pollen has been disregarded by many people from the qualitative rather that quantitative results they provide. (Douglas, Schetter, 1997, 91)
Dendrochronology has been a scientific method which has helped in studying and focusing the climatic changes across the globe over the Holocene era. This is the analysis of growth patterns of tree rings through scientific dating process. Its invention was in the 20th century. Through the technique, wood dating has been given the exact dates. The process has been through cross-sectional cutting of tree trunks and analyzing the status of their growth rings. Scientifically, such growth rings occurs as a result of the new vascular cambiums. Visible rings have been credited to the changing growth speed which occur in different yearly seasons. Accordingly, a ring in the study has been used to signify one-year time span in the growth of such a tree. Greater visibility in the rings occurs to trees within temperate zones in which yearly seasons differ less often. (Thomas, Richard, 34)
Accordingly, the proportional characteristics in the rings has also provided for the different seasons of the years in which the growth was taking place. Either, springwood occurs when growth is rapid which leads to a low-density wood. Late wood is developed during the summer season. The basic use of tree rings has provided for chronological development about the various climatic changes affecting the tree growth at different times. Consequently, studies have shown that different tree growth characteristics as provided by the wood rings respond to a wide variety of climatic conditions that lapsed during such tree growth. Elsewhere, temperate trees have significantly showed changes in their ring pattern which has signified changing climatic conditions with which the tree grew in. Scientifically, adequate moisture which provides long seasons of growth have resulted in synonymously wide rings. Also, dry conditions have resulted in narrow rings. Due to changes in climatic conditions across the year, a broad array of rings has been the resulting characteristics in trees. (Thomas, Richard, 37) Elsewhere, the concept of dendrochronology has also been used in describing the source of trees growth. Consequently, those trees which have the same climatic zones in their development have been seen to have the same nature of rings. This has meant that, trees across different climatic zones have different layering in their rings.
Indeed therefore, chronological developments can be made across the board in regard to the biotic characteristics influence for all the global regions as well as partial world zones and sub-regions. Through the scientific concept of cross dating, wood samples from the ancient times can adequately be matched with corresponding chronological authorities through which case the age and growth conditions of the wood can be determined.
Though the method is counterfeit in variations, smooth average width from tree rings have been examined by dendrochronologists. The historical development of the trees has therefore buildup on the actual extend/exact dates of tree rings have been known. Consequently, cross-matching process has been used in evaluating various tree species in regard to their floating chronology results. Historically, such chronological events have dated back to even 10000 years ago.
Dendrochronological results have provided various implications in the growth patterns of trees. Despite the same sub-region tree growing environments, different tree layers have showed wide range responding diversity in their ring layers. According to chronological arguments, the changing patterns of tree layers have been as a result of changing environmental conditions of tree growing areas. The environmental conditions has however been influenced by the change in the climatic conditions across the different tree growing zones. Through dendrochronology, specimens from scientific researches have adequately been corresponded to a specific year of growth through the process of radiocarbon dating.
Through the phenomenological characteristics of tree rings, such characteristics have been allied to changing climatic conditions which has led to changes in the growth nature of trees. Through the physical conditions in the change of the tree rings therefore, a change in the climatic conditions have been associated with changes in the growth characteristics of such tree rings. However, dendrochronological results have highly been discredited by many people due to the scope of ambiguity in the result finding and methodologies. (Diver, Chapman, 2002, 93) Firstly, the exact time gallery and characteristics of the trees is not solely influenced by the scope of climatic conditions but has been influenced by other biotic factors such as different ant species that cause changes and destruction to the ring structures. Either, since dendrochronology borrows its techniques of assembly fro the sedimentary dating, the weaknesses of using sedimentary dating to qualify for dendrochronology has been seen as a big problem that has paused rejection of this tool. Either, the exact age in the buildup of the ring structure that corresponds to specific climatic condition may be difficult in its development. These conditions has paused a serious threat in agreeing upon dendrochronology as a method for studying climatic changes during the Holocene era. (Diver, Chapman, 2002, 95)
However, from its diverse study in the tree growth chronology in response to various changes in weather conditions, the tool has been an important one in explaining the volatility in the climatic changes across the Holocene era. It has helped to provide a comparatively valid support for the possible changes in the global climate.
Summarily therefore, ancient chronologies about climate provide that the state of climate in the early ages of the Holocene era was evidently favorable. The future of the same is perhaps questionable from the current trends. Generally, great epochs have characterized development in climatic patterns from very adequate to a poor and severe modern climate which is accompanied by desert and semi-desert conditions. Either, great epochs of industrialization has seen adverse changes in the climatic autonomy. The future state of the world climate would perhaps be more sphere and critical with adverse climatic conditions.
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Douglas, V & Schetter, K. The Role of the Sun IN climatic Change. Oxford, Oxford University Press, 1997, pp.91
Mannion, A. Natural Environmental Change. The Last 3 Million Years. London, Routledge, 1999, pp.71
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