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Research paper−78−Synthesiology - English edition Vol.5 No.2 pp.78-87 (Sep. 2012) subtropical zones. It was shown that the sea temperatures of the recent two hundred years were clearly higher than the past period, through the records left in the extant large corals from several areas of low-latitude waters, and this is considered to be a major accomplishment of coral skeletal climatology. Figure 2 shows the research subjects used in the paleoclimate reconstruction and the positioning of the coral skeletal research.[1][2]It is also an important issue to reconstruct the climate from the 1 IntroductionObservation records of the ocean and land at high resolution over a long time span are necessary in order to understand the climate change at a global scale. However, there are very few records of marine observation using measuring equipment before 1950. Therefore, the reconstruction of marine temperature, rainfall, and salinity over the past several hundred years using the annual growth bands from the skeletons of massive reef-building coral colonies has drawn attention (Figs. 1 and 2). The annual bands in the coral skeletons were discovered in 1933, but they became the subject of active research after 1995, and only recently the research has developed into “coral skeletal climatology” (Fig. 3). In this paper, I shall explain why the coral skeleton is excellent as a recording medium of the past global climate change, and describe the major developments where the latest analysis technology is being utilized to read the past records.Under the title “Paleoclimate” in Chapter 7 of Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change[1] published in 2007, researches on climate changes from several years to several hundred thousand years were reviewed. In this report, there were many citations of the results of marine environment reconstruction at high temporal resolution (about two weeks) using indirect indices such as the oxygen isotope ratio of coral samples from the tropical and - Understanding the oceanic history through precise chemical and isotope analyses of coral annual bands-Global warming (due to increased carbon dioxide in the atmosphere) has attracted much attention. Yet, predicting trends in the Earth's climate remains difficult. A more sophisticated and accurate global warming model can be obtained by reconstructing climatic change since the Industrial Revolution, and other past periods of warming. To this end, a promising area of research in marine science is coral skeletal climatology, which offers a unique method for accurately reconstructing marine temperature and saline concentration over the past several hundred years, with a high temporal resolution (ca. 2 weeks) based on chemical and isotope analysis of long-lived coral skeletons. This method has been successfully applied to the Little Ice Age around the 18th century and the mid-Pliocene warming period of 3.5 million years ago. It can also be applied to biological and environment studies on massive coral bleaching events caused by unusually high oceanic temperature levels and other environmental issues such as ocean acidification.Paleoclimate reconstruction and future forecast based on coral skeletal climatologyKeywords : coral, climate, global warming, ocean, oxygen isotope ratio[Translation from Synthesiology, Vol.5, No.2, p.80-88 (2012)]Atsushi SuzukiInstitute of Geology and Geoinformation, AIST Tsukuba Central 7, 1-1-1 Higashi, Tsukuba 305-8567, Japan Original manuscript received September 15, 2011, Revisions received April 9, 2012, Accepted April 26, 20121 cm1 m1 yearFig. 1 Massive colony of Porites (left) seen in the coral reef of Ishigaki Island, Ryukyu Islands and the x-ray positive photograph of a columnar sample (right)In the x-ray photograph, the dark colored band corresponds to the high-density area, and the light colored band corresponds to the low-density area. One set of dark and light colored bands represents one annular ring.

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