page_title: Global temperature record
section_title: Geologic evidence (millions of years)
hierarchical_section_title: Global temperature record / Geologic evidence (millions of years)
caption_attribution_description: reconstruction of the past 5 million years of climate history, based on oxygen isotope fractionation (serving as a proxy for the total global mass of glacial ice sheets). See the discussion below for a summary of the methods and models used. Note that in 2010, User:SeL media switched the orientation of the time axis and the vertical axes, apparently without discussion, and some descriptions of the image may refer to the older version, resulting in confusion of 'right' and 'left' in the image.
context_page_description: The global temperature record shows the fluctuations of the temperature of the atmosphere and the oceans through various spans of time. The most detailed information exists since 1850, when methodical thermometer-based records began. There are numerous estimates of temperatures since the end of the Pleistocene glaciation, particularly during the current Holocene epoch. Older time periods are studied by paleoclimatology.
context_section_description: On longer time scales, sediment cores show that the cycles of glacials and interglacials are part of a deepening phase within a prolonged ice age that began with the glaciation of Antarctica approximately 40 million years ago.  This deepening phase, and the accompanying cycles, largely began approximately 3 million years ago with the growth of continental ice sheets in the Northern Hemisphere.  Gradual changes in Earth's climate of this kind have been frequent during the Earth's 4500 million year existence and most often are attributed to changes in the configuration of continents and ocean sea ways.
caption: Reconstruction of the past 5 million years of climate history, based on oxygen isotope fractionation in deep sea sediment cores (serving as a proxy for the total global mass of glacial ice sheets), fitted to a model of orbital forcing (Lisiecki and Raymo 2005)[14] and to the temperature scale derived from Vostok ice cores following Petit et al. (1999).[15]
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