How Scientists Determine Climates of the Past

How Scientists Determine Climates of the Past Paleoenvironmental reconstruction (also known as paleoclimate reconstruction) refers to the results and the investigations undertaken to determine what the climate and vegetation were like at a particular time and place in the past. Climate, including vegetation, temperature, and relative humidity, has varied considerably during the time since the earliest human habitation of planet earth, from both natural and cultural (human-made) causes. Climatologists primarily use paleoenvironmental data to understand how the environment of our world has changed and how modern societies need to prepare for the changes to come. Archaeologists use paleoenvironmental data to help understand the living conditions for the people who lived at an archaeological site. Climatologists benefit from the archaeological studies because they show how humans in the past learned how to adapt or failed to adapt to environmental change, and how they caused environmental changes or made them worse or better by their actions. Using Proxies The data that are collected and interpreted by paleoclimatologists are known as proxies, stand-ins for what cant be directly measured. We cant travel back in time to measure the temperature or humidity of a given day or year or century, and there are no written records of climatic changes that would give us those details older than a couple of hundred years. Instead, paleoclimate researchers rely on biological, chemical, and geological traces of past events that were influenced by the climate. The primary proxies used by climate researchers are plant and animal remains because the type of flora and fauna in a region indicates the climate: think of polar bears and palm trees as indicators of local climates. Identifiable traces of plants and animals range in size from whole trees to microscopic diatoms and chemical signatures. The most useful remains are those that are large enough to be identifiable to species; modern science has been able to identify objects as tiny as pollen grains and spores to plant species. Keys to Past Climates Proxy evidence can be biotic, geomorphic, geochemical, or geophysical; they can record environmental data that range in time from yearly, every ten years, every century, every millennium or even multi-millennia. Events such as tree growth and regional vegetation changes leave traces in soils and peat deposits, glacial ice and moraines, cave formations, and in the bottoms of lakes and oceans. Researchers rely on modern analogs; that is to say, they compare the findings from the past to those found in current climates around the world. However, there are periods in the very ancient past when the climate was completely different from what is currently being experienced on our planet. In general, those situations appear to be the result of climate conditions that had more extreme seasonal differences than any weve experienced today. It is particularly important to recognize that atmospheric carbon dioxide levels were lower in the past than those present today, so ecosystems with less  greenhouse gas  in the atmosphere likely behaved differently than they do today. Paleoenvironmental Data Sources There are several types of sources where paleoclimate researchers can find preserved records of past climates. Glaciers and Ice Sheets: Long-term bodies of ice, such as the Greenland and Antarctic ice sheets, have annual cycles which build new layers of ice each year like tree rings. Layers in the ice vary in texture and color during warmer and cooler parts of the year. Also, glaciers expand with increased precipitation and cooler weather and retract when warmer conditions prevail. Trapped in those layers laid down over thousands of years are dust particles and gases which were created by climatic disturbances such as volcanic eruptions, data which can be retrieved using ice cores.Ocean Bottoms: Sediments are deposited in the bottom of the oceans each year, and lifeforms such as foraminifera, ostracods, and diatoms die and are deposited with them. Those forms respond to ocean temperatures: for example, some are more prevalent during warmer periods.Estuaries and Coastlines: Estuaries preserve information about the height of former sea levels in long sequences of alternating layers of organic p eat when the sea level was low, and inorganic silts when the sea level rose. Lakes: Like oceans and estuaries, lakes also have annual basal deposits called varves. Varves hold a wide variety of organic remains, from entire archaeological sites to pollen grains and insects. They can hold information about environmental pollution such as acid rain, local iron mongering, or run-offs from eroded hills nearby.Caves: Caves are closed systems, where average annual temperatures are maintained year-round and with a high relative humidity. Mineral deposits within caves such as stalactites, stalagmites, and flowstones gradually form in thin layers of calcite, which trap chemical compositions from outside the cave. Caves can thus contain continuous, high-resolution records which can be dated using uranium-series dating.Terrestrial Soils: Soil deposits on land can also be a source of information, trapping animal and plant remains in colluvial deposits at the base of hills or alluvial deposits in valley terraces. Archaeological Studies of Climate Change Archaeologists have been interested in climate research since at least Grahame Clarks 1954 work at Star Carr. Many have worked with climate scientists to figure out the local conditions at the time of occupation. A trend identified by Sandweiss and Kelley (2012) suggests that climate researchers are beginning to turn to the archaeological record to assist with the reconstruction of paleoenvironments. Recent studies described in detail in Sandweiss and Kelley include: The interaction between humans and climatic data to determine the rate and extent of El Nià ±o and the human reaction to it over the last 12,000 years of people living in coastal Peru.Tell Leilan in northern Mesopotamia (Syria) deposits matched to ocean drilling cores in the Arabian Sea identified a previously-unknown volcanic eruption that took place between 2075-1675 BC, which in turn may have led to an abrupt aridification with the abandonment of the tell and may have led to the disintegration of the Akkadian empire.In the Penobscot valley of Maine in the northeastern United States, studies on sites dated to the early-middle Archaic (~9000-5000 years ago), helped establish a chronology of flood events in the region associated with falling or low lake levels.Shetland Island, Scotland, where Neolithic-aged sites are sand-inundated, a situation believed to be an indication of a period of storminess in the North Atlantic. Sources Allison AJ, and Niemi TM. 2010. Paleoenvironmental reconstruction of Holocene coastal sediments adjacent to archaeological ruins in Aqaba, Jordan. Geoarchaeology 25(5):602-625.Dark P. 2008. Paleoenvironmental reconstruction, methods. In: Pearsall DM, editor. Encyclopedia of Archaeology. New York: Academic Press. p 1787-1790.Edwards KJ, Schofield JE, and Mauquoy D. 2008. High resolution paleoenvironmental and chronological investigations of Norse landnm at Tasiusaq, Eastern Settlement, Greenland. Quaternary Research 69:1–15.Gocke M, Hambach U, Eckmeier E, Schwark L, Zà ¶ller L, Fuchs M, Là ¶scher M, and Wiesenberg GLB. 2014. Introducing an improved multi-proxy approach for paleoenvironmental reconstruction of loess–paleosol archives applied on the Late Pleistocene Nussloch sequence (SW Germany). Palaeogeography, Palaeoclimatology, Palaeoecology 410:300-315.Lee-Thorp J, and Sponheimer M. 2015. Contribution of Stable Light Isotopes to Paleoenvironmental Reconstruction. I n: Henke W, and Tattersall I, editors. Handbook of Paleoanthropology. Berlin, Heidelberg: Springer Berlin Heidelberg. p 441-464. Lyman RL. 2016. The mutual climatic range technique is (usually) not the area of sympatry technique when reconstructing paleoenvironments based on faunal remains. Palaeogeography, Palaeoclimatology, Palaeoecology 454:75-81.Rhode D, Haizhou M, Madsen DB, Brantingham PJ, Forman SL, and Olsen JW. 2010. Paleoenvironmental and archaeological investigations at Qinghai Lake, western China: Geomorphic and chronometric evidence of lake level history. Quaternary International 218(1–2):29-44.Sandweiss DH, and Kelley AR. 2012. Archaeological Contributions to Climate Change Research: The Archaeological Record as a Paleoclimatic and Paleoenvironmental Archive*. Annual Review of Anthropology 41(1):371-391.Shuman BN. 2013. Paleoclimate reconstruction - Approaches In: Elias SA, and Mock CJ, editors. Encyclopedia of Quaternary Science (Second Edition). Amsterdam: Elsevier. p 179-184.

Writing a Personal Journal

Writing a Personal Journal A journal is a written record of incidents, experiences, and ideas. Also known as a  personal journal,  notebook, diary, and log. Writers often keep journals to record observations and explore ideas that may eventually be developed into more formal essays, articles, and stories. The  personal journal is  a very private document, says  Brian Alleyne, a place where the author records and reflects on lifes events. Knowledge of the self in the  personal journal is  retrospective knowledge and therefore potentially narrative self-knowledge (Narrative Networks, 2015). Observations The writers journal is a record of and workbook for your writing life. It is your repository for bits of experience, observation and thought destined for eventual use in one writing project or another. The entries in a personal journal tend to be abstract, but the entries in a writers journal should be concrete. (Alice Orr, No More Rejections. Writers Digest Books, 2004)All of us who keep journals do so for different reasons, I suppose, but we must have in common a fascination with the surprising patterns that emerge over the years- a sort of arabesque in which certain elements appear and reappear, like the designs in a well-wrought novel. (Joyce Carol Oates, interviewed by Robert Phillips. The Paris Review, Fall-Winter 1978)Think nothing too trifling to write down, so it be in the smallest degree characteristic. You will be surprised to find on reperusing your journal what an importance and graphic power these little particulars assume. (Nathaniel Hawthorne, letter to Horatio Bridge , May 3, 1843) Poet Stephen Spender: Write Anything I feel as though I could not write again. Words seem to break in my mind like sticks when I put them down on paper. . . . I must put out my hands and grasp the handfuls of facts. How extraordinary they are! The aluminum balloons seem nailed into the sky like those bolts which hold together the irradiating struts between the wings of a biplane. The streets become more and more deserted, and the West End is full of shops to let. Sandbags are laid above the glass pavements over basements along the sidewalk. . . . The best thing is to write anything, anything that comes into my mind until there is a calm and creative day. It is essential to be patient and to remember that nothing one feels is the last word. (Stephen Spender, Journal, London, September 1939) Orwells Notebook Entry Curious effect, here in the sanatorium, on Easter Sunday, when people in this (the most expensive) block of chalets mostly have visitors, of hearing large numbers of upper-class English voices. . . . And what voices! A sort of over-fedness, a fatuous self-confidence, a constant bah-bahing of laughter abt nothing, above all a sort of heaviness and richness combined with a fundamental ill will. (George Orwell, notebook entry for April 17, 1949, Collected Essays 1945-1950) Functions of a Journal Many professional writers use journals, and the habit is a good one for anybody interested in writing, even if he or she has no literary ambitions. Journals store perceptions, ideas, emotions, actions- all future material for essays or stories. The Journals of Henry Thoreau are a famous example, as are A Writers Diary by Virginia Woolf, the Notebooks of the French novelist Albert Camus, and A War-time Diary by the English writer George Orwell. If a journal is really to help you develop as a writer, youve got to do more than compose trite commonplaces or mechanically list what happens each day. You have to look honestly and freshly at the world around you and at the self within. (Thomas S. Kane, The New Oxford Guide to Writing. Oxford University Press, 1988) Thoreaus Journals As repositories of facts, Thoreaus journals act like a writers warehouse in which he indexes his stored observations. Here is a typical list: It occurs to me that these phenomena occur simultaneously, say June 12, viz:Heat about 85 at 2P.M. True summer. Hylodes cease to peep. Purring frogs ( Rana palustris) cease. Lightning bugs first seen. Bullfrogs trump generally. Mosquitoes begin to be really troublesome. Afternoon thunder-showers almost regular. Sleep with open window (10th), and wear thin coat and ribbon neck. Turtles fairly and generally begun to lay. [15 June 1860] In addition to their function as storage, the journals constitute a complex of processing plants as well, where the notations become descriptions, meditations, ruminations, judgments, and other types of studies: From all points of the compass, from the earth beneath and the heavens above, have come these inspirations and been entered duly in the order of arrival in the journal. Thereafter, when the time arrived, they were winnowed into lectures, and again, in due time, from lectures into essays (1845-1847). In short, in the journals, Thoreau negotiates the transformation of facts into forms of written expressions that have entirely different orders of resonance . . .. (Robert E. Belknap, The List: The Uses and Pleasures of Cataloguing. Yale University  Press, 2004) A Contrarians View People ask whether I use a notebook, and the answer is no. I think a writers notebook is the best way there is to immortalize really bad ideas, whereas the Darwinian process takes place if you dont write anything down. The bad ones float away, and the good ones stay. (Stephen King, quoted in Whats on Stephen Kings Dark Side? by Brian Truitt. USA Weekend, October  29-31, 2010) Are Journal-Keepers Introspective or Self-Absorbed? Some people like to keep a journal. Some people think it’s a bad idea. People who keep a journal often see it as part of the process of self-understanding and personal growth. They don’t want insights and events to slip through their minds. They think with their fingers and have to write to process experiences and become aware of their feelings. People who oppose journal-keeping fear it contributes to self-absorption and narcissism. C.S. Lewis, who kept a journal at times, feared that it just aggravated sadness and reinforced neurosis. Gen. George Marshall did not keep a diary during World War II because he thought it would lead to self-deception or hesitation in reaching decisions. The question is: How do you succeed in being introspective without being self-absorbed? (David Brooks, Introspective or Narcissistic? The New York Times, August 7, 2014)