Predicting trends in atmospheric CO 2 across the Mid-Pleistocene Transition using existing climate archives
During the Mid-Pleistocene Transition (MPT), ca. 1200–800 000 years ago (ka), the Earth's glacial cycles changed from 41 to 100 kyr periodicity. The emergence of this longer ice age periodicity was accompanied by higher global ice volume in glacial periods and lower global ice volume in intergl...
| Published in: | Climate of the Past |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Copernicus Publications
2024
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/cp-20-2487-2024 https://doaj.org/article/a7a2f4cf42aa4dbdbeacaf3cd50dcc3b |
| Summary: | During the Mid-Pleistocene Transition (MPT), ca. 1200–800 000 years ago (ka), the Earth's glacial cycles changed from 41 to 100 kyr periodicity. The emergence of this longer ice age periodicity was accompanied by higher global ice volume in glacial periods and lower global ice volume in interglacial periods. Since there is no known change in external orbital forcing across the MPT, it is generally agreed that the cause of this transition is internal to the Earth system. Resolving the climate, carbon cycle, and cryosphere processes responsible for the MPT remains a major challenge in Earth and palaeoclimate science. To address this challenge, the international ice core community has prioritised recovery of an ice core record spanning the MPT interval. Here we present results from a simple generalised least-squares (GLS) model that predicts atmospheric CO 2 out to 1.8 Myr. Our prediction utilises existing records of atmospheric carbon dioxide ( CO 2 ) from Antarctic ice cores spanning the past 800 kyr along with the existing LR04 benthic δ 18 O calcite <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="50pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="e239a5aaf7eafa15f9a3873dd31d8c36"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cp-20-2487-2024-ie00001.svg" width="50pt" height="16pt" src="cp-20-2487-2024-ie00001.png"/></svg:svg> stack (Lisiecki and Raymo, 2005; hereafter “benthic δ 18 O stack”) from marine sediment cores. Our predictions assume that the relationship between CO 2 and benthic δ 18 O over the past 800 000 years can be extended over the last 1.5 million years. The implicit null hypothesis is that there has been no fundamental change in feedbacks between atmospheric CO 2 and the climate parameters represented by benthic δ 18 O , global ice volume, and ocean temperature. We test the GLS-model-predicted CO 2 concentrations against observed blue ice CO 2 concentrations, δ 11 B -based CO 2 reconstructions from marine sediment cores, and δ 13 C of ... |
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