Editing Isotope analysis (section)

=== Paleoclimatology ===
The ratio of <sup>18</sup>O to <sup>16</sup>O in ice and deep sea cores is temperature dependent, and can be used as a proxy measure for [[paleoclimatology|reconstructing climate change]]. During colder periods of the Earth's history (glacials) such as during the [[ice age]]s, <sup>16</sup>O is preferentially evaporated from the colder oceans, leaving the slightly heavier and more sluggish <sup>18</sup>O behind. Organisms such as [[foraminifera]] which combine oxygen dissolved in the surrounding water with carbon and calcium to build their shells therefore incorporate the temperature-dependent <sup>18</sup>O to <sup>16</sup>O ratio. When these organisms die, they settle out on the sea bed, preserving a long and invaluable record of global climate change through much of the [[Quaternary]].<ref>{{cite journal |doi=10.1016/j.quascirev.2011.07.007 |title=Late Pleistocene monsoon variability in northwest Thailand: An oxygen isotope sequence from the bivalve Margaritanopsis laosensis excavated in Mae Hong Son province |journal=Quaternary Science Reviews |volume=30 |issue=21–22 |pages=3088–98 |year=2011 |last1=Marwick |first1=Ben |last2=Gagan |first2=Michael K |bibcode=2011QSRv...30.3088M |s2cid=15182044 }}</ref> Similarly, ice cores on land are enriched in the heavier <sup>18</sup>O relative to <sup>16</sup>O during warmer climatic phases ([[interglacial]]s) as more energy is available for the evaporation of the heavier <sup>18</sup>O isotope. The oxygen isotope record preserved in the ice cores is therefore a "mirror" of the record contained in ocean sediments.<ref>{{Citation | vauthors=((Wolff, E. W.)), ((Fischer, H.)), ((Ommen, T. van)), ((Hodell, D. A.)) | year=2022 | title=Stratigraphic templates for ice core records of the past 1.5 Myr | journal=Nature | volume=18 | issue=7 | pages=1563–1577 | doi=10.5194/cp-18-1563-2022 | doi-access=free | bibcode=2022CliPa..18.1563W }}</ref>

[[Oxygen isotope]]s preserve a record of the effects of the [[Milankovitch cycles]] on climate change during the Quaternary, revealing an approximately 100,000-year [[cyclicity]] in the [[Earth's climate]].<ref>{{Citation | vauthors=((Petit, J. R.)), ((Jouzel, J.)), ((Raynaud, D.)), ((Barkov, N. I.)), ((Barnola, J.-M.)), ((Basile, I.)), ((Bender, M.)), ((Chappellaz, J.)), ((Davis, M.)), ((Delaygue, G.)), ((Delmotte, M.)), ((Kotlyakov, V. M.)), ((Legrand, M.)), ((Lipenkov, V. Y.)), ((Lorius, C.)), ((PÉpin, L.)), ((Ritz, C.)), ((Saltzman, E.)), ((Stievenard, M.)) | year=1999 | title=Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica | journal=Climate of the Past | volume=399 | issue=6735 | pages=429–436 | doi=10.1038/20859 | bibcode=1999Natur.399..429P | s2cid=204993577 | url=http://dx.doi.org/10.1038/20859}}</ref>