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RE: Ancient climate
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 14,600 years ago, the sea rose very rapidly during a period of warming

14,600 years ago, the sea level increased sharply by almost 14 meters in just 350 years. This impressive rise coincides with the beginning of the first hot period that marked the end of the last glaciation. Moreover, the contribution of the Antarctic ice sheet to sea level rise has been significant. These are the results highlighted by a team from the European Centre for Research and Teaching in Environmental Geosciences (CEREGE, University Aix-Marseille / CNRS / IRD / College de France), in collaboration with English and Japanese colleagues. Published 29 March 2012 in the journal Nature, these studies confirm the existence of a major acceleration of sea level rise between 14,650 and 14,300: this is one of the most significant weather events of last 20,000 years.
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Bølling interstadial period
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  Coral links ice to ancient 'mega flood'

Coral off Tahiti has linked the collapse of massive ice sheets 14,600 years ago to a dramatic and rapid rise in global sea-levels of around 14 metres.
revious research could not accurately date the sea-level rise but now an Aix-Marseille University-led team, including Oxford University scientists Alex Thomas and Gideon Henderson, has confirmed that the event occurred 14,650-14,310 years ago at the same time as a period of rapid climate change known as the Bølling warming.

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Confidence in Climate Data: Using 3 Million-Year-Old Records

How do we understand what's happening today by looking back millions of years?
Scientists are looking at what climate conditions were like 3.3 to 3 million years ago, during a geologic period known as the Pliocene, and they are confident in the accuracy of their data.
The Pliocene is the most recent period of sustained global warmth similar to what is projected for the 21st century. Climate during this time period offers one of the closest analogy to estimate future climate conditions.

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Ancient Arabic writings can help redo past climate

Ancient manuscripts written by Arabic scholars during the 9th and 10th centuries can provide valuable meteorological information to help modern scientists reconstruct the climate of the past, according to a new study.
The research analyses the writings of scholars, historians and diarists in Iraq during the Islamic Golden Age between 816-1009 AD for evidence of abnormal weather patterns.

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Title: Assessing the Medieval Climate Anomaly in the Middle East: The potential of Arabic documentary sources
Authors: Steffen Vogt, R. Glaser, J. Luterbacher, D. Riemann, Gh. Al Dyab, J. Schoenbein and E. Garcia-Bustamante

New evidence from documentary sources provides detailed climatic information to fill the Middle East gap in Medieval Climate Anomaly reconstructions.

The Middle East region harbours a wealth of documentary and natural archives that contain detailed information on climate conditions and events. To date, however, only a few proxy-based climate reconstructions are available from the area for the assessment of thermal and hydroclimatic characteristics of the Medieval Climate Anomaly (MCA). Existing chronologies and reconstructions mostly provide information for specific seasons and hydroclimatic parameters (commonly precipitation and droughts). The reconstructions are based on natural proxies such as tree rings (e.g., Touchan et al., 2007), pollen records (Kaniewski et al., 2010), speleothems (e.g., Bar Matthews et al., 1997; Frumkin et al., 1991; Fleitmann et al., 2004), lake sedimentary records (e.g., Kuzucuoglu et al., 2011), Dead Sea sedimentary records (e.g., Enzel et al., 2003; Migowski et al., 2006) or Red Sea corals (e.g., Felis and Nimbur, 2010). For compilations of available data from natural and documentary archives the reader is referred to Luterbacher et al. (2006, 2011) and references therein. Most of this data is hampered by a high degree of spatial and temporal variability and/or insufficient spatio-temporal resolution to assess in detail the MCA climate. Therefore its spatial and temporal extent in the Middle East requires further investigations.

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Paleoclimate Record Points Toward Potential Rapid Climate Changes

New research into the Earth's paleoclimate history by NASA's Goddard Institute for Space Studies director James E. Hansen suggests the potential for rapid climate changes this century, including multiple meters of sea level rise, if global warming is not abated.
By looking at how the Earth's climate responded to past natural changes, Hansen sought insight into a fundamental question raised by ongoing human-caused climate change: "What is the dangerous level of global warming?" Some international leaders have suggested a goal of limiting warming to 2 degrees Celsius from pre-industrial times in order to avert catastrophic change. But Hansen said at a press briefing at a meeting of the American Geophysical Union in San Francisco on Tues, Dec. 6, that warming of 2 degrees Celsius would lead to drastic changes, such as significant ice sheet loss in Greenland and Antarctica.
Based on Hansen's temperature analysis work at the Goddard Institute for Space Studies, the Earth's average global surface temperature has already risen .8 degrees Celsius since 1880, and is now warming at a rate of more than .1 degree Celsius every decade. This warming is largely driven by increased greenhouse gases in the atmosphere, particularly carbon dioxide, emitted by the burning of fossil fuels at power plants, in cars and in industry. At the current rate of fossil fuel burning, the concentration of carbon dioxide in the atmosphere will have doubled from pre-industrial times by the middle of this century. A doubling of carbon dioxide would cause an eventual warming of several degrees, Hansen said.

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Bond event
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Bond events are North Atlantic climate fluctuations occurring every ~1,470 ± 500 years throughout the Holocene. Eight such events have been identified, primarily from fluctuations in ice-rafted debris. Bond events may be the interglacial relatives of the glacial Dansgaard-Oeschger events, with a magnitude of perhaps 15-20% of the glacial-interglacial temperature change.
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55 million years of climate change

State-of-the-art climate models, as used in the assessments of the Intergovernmental Panel for Climate Change, could be giving a false sense of security in terms of upcoming abrupt change, suggests a Commentary by a University of Bristol scientist published online this week in Nature Geoscience.
Professor Paul Valdes of the School of Earth Sciences, discusses four examples of abrupt climate change spanning the past 55 million years that have been reconstructed from palaeoclimate data.

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Title: Climate related sea-level variations over the past two millennia
Authors: Kemp, A.C., Horton, B.P., Donnelly, J.P., Mann, M.E., Vermeer, M., Rahmstorf, S.

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Early Antarctic Circumpolar Current Development Impacted Global Climate

Thirty-eight million years ago, tropical jungles thrived in what are now the cornfields of the American Midwest and furry marsupials wandered temperate forests in what is now the frozen Antarctic. The temperature differences of that era, known as the late Eocene, between the equator and Antarctica were only half of what they are today. A debate has long been raging in the scientific community on what changes in our global climate system led to such a major shift from the more tropical, greenhouse climate of the Eocene to the modern and much cooler climates of today.
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