![]() ![]() Given that the confidence levels surrounding all of the reconstructions are wide, virtually all reconstructions are effectively encompassed within the uncertainty previously indicated in the TAR. The result is a picture of relatively cool conditions in the seventeenth and early nineteenth centuries and warmth in the eleventh and early fifteenth centuries, but the warmest conditions are apparent in the twentieth century. when viewed together, the currently available reconstructions indicate generally greater variability in centennial time scale trends over the last 1 kyr than was apparent in the TAR. ![]() The IPCC Fourth Assessment Report (AR4) of 2007 discusses more recent research and gives particular attention to the Medieval Warm Period: hemispherically, the "Little Ice Age" can only be considered as a modest cooling of the Northern Hemisphere during this period of less than 1☌ relative to late twentieth century levels. Thus current evidence does not support globally synchronous periods of anomalous cold or warmth over this interval, and the conventional terms of "Little Ice Age" and " Medieval Warm Period" appear to have limited utility in describing trends in hemispheric or global mean temperature changes in past centuries. However, the timing of maximum glacial advances in these regions differs considerably, suggesting that they may represent largely independent regional climate changes, not a globally-synchronous increased glaciation. The Intergovernmental Panel on Climate Change Third Assessment Report (TAR) of 2001 described the areas that were affected:Įvidence from mountain glaciers does suggest increased glaciation in a number of widely spread regions outside Europe prior to the twentieth century, including Alaska, New Zealand and Patagonia. Several causes have been proposed: cyclical lows in solar radiation, heightened volcanic activity, changes in the ocean circulation, variations in Earth's orbit and axial tilt ( orbital forcing), inherent variability in global climate, and decreases in the human population (such as from the Black Death and the epidemics emerging in the Americas upon European contact ). At most, there was modest cooling of the Northern Hemisphere during the period. The Intergovernmental Panel on Climate Change Third Assessment Report considered that the timing and the areas affected by the Little Ice Age suggested largely independent regional climate changes, rather than a globally synchronous increased glaciation. One began about 1650, another about 1770, and the last in 1850, all of which were separated by intervals of slight warming. The NASA Earth Observatory notes three particularly cold intervals. The period has been conventionally defined as extending from the 16th to the 19th centuries, but some experts prefer an alternative timespan from about 1300 to about 1850. The term was introduced into scientific literature by François E. It was not a true ice age of global extent. The Little Ice Age ( LIA) was a period of regional cooling, particularly pronounced in the North Atlantic region. Am J Obstet Gynecol 2015 212:50.e1-8.Global average temperatures show that the Little Ice Age was not a distinct planet-wide period but a regional phenomenon occurring near the end of a long temperature decline that preceded the recent global warming. ![]() Association of short-term bleeding and cramping patterns with long-acting reversible contraceptive method satisfaction. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.Ĭite this article as: Diedrich JT, Desai S, Zhao Q, et al. The remaining authors report no conflict of interest. receives research funding from Bayer Healthcare Pharmaceuticals, Teva Pharmaceuticals, and Merck and serves on advisory boards for Teva Pharmaceuticals, Bayer Healthcare Pharmaceuticals, MicroCHIPS, and Watson/Activis. serves on an advisory board for Bayer Healthcare Pharmaceuticals. This publication also was supported by the Washington University Institute of Clinical and Translational Sciences grant number UL1 TR000448 from the National Center for Advancing Translational Sciences and award number K23HD070979 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development. ![]() The Contraceptive CHOICE Project is funded by the Susan T.
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