Atmospheric CO2 20 Million Year Foraminiferal B/Ca Reconstruction Tripati, A.K.; Roberts, C.D.; Eagle, R.A. Tripati, A.K. Roberts, C.D. Eagle, R.A. Atmospheric Gas Reconstruction carbon cycle earth science/paleoclimate/paleoceanography (boron/calcium,planktic foraminifer,null,micromole per mole,null,paleoceanography,null,null,N,null) earth science/paleoclimate/climate forcing (carbon dioxide,null,range upper bound,parts per million,null,climate forcing,null,null,N,foraminifer boron/calcium) earth science/paleoclimate/paleoceanography (depth,null,null,meter,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (delta 13C,planktic foraminifer,null,per mil PDB,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,N,species analyzed) earth science/paleoclimate/climate forcing (carbon dioxide,null,null,parts per million,null,climate forcing,averaged,null,N,foraminifer boron/calcium) earth science/paleoclimate/climate forcing (carbon dioxide,null,range lower bound,parts per million,null,climate forcing,null,null,N,foraminifer boron/calcium) earth science/paleoclimate/paleoceanography (magnesium/calcium,planktic foraminifer,null,millimole per mole,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (delta 18O,planktic foraminifer,null,per mil PDB,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (age,null,null,million years ago,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean (DSDP 588>LATITUDE -26>LONGITUDE 161) (ODP 806B>LATITUDE .32>LONGITUDE 159.35) The carbon dioxide (CO2) content of the atmosphere has varied cyclically between ~180 and ~280 parts per million by volume over the past 800,000 years, closely coupled with temperature and sea level. For earlier periods in Earth's history, the partial pressure of CO2 (pCO2) is much less certain, and the relation between pCO2 and climate remains poorly constrained. We use boron/calcium ratios in foraminifera to estimate pCO2 during major climate transitions of the past 20 million years. During the Middle Miocene, when temperatures were ~3 to 6C warmer and sea level was 25 to 40 meters higher than at present, pCO2 appears to have been similar to modern levels. Decreases in pCO2 were apparently synchronous with major episodes of glacial expansion during the Middle Miocene (~14 to 10 million years ago) and Late Pliocene (~3.3 to 2.4 million years ago). STUDY NOTES: Paleoatmospheric CO2 concentrations estimated from the boron/calcium ratio of planktonic foraminifera. Samples from Deep Sea Drilling Project Site 588 and Ocean Drilling Program Site 806 were used to reconstruct pCO2 values from the Miocene through Holocene (~20 to 0 Ma). Average, maximum, and minimum pCO2 estimates are calculated for each time. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Tripati, A.K. Investigator : Roberts, C.D. Investigator : Eagle, R.A. 2010-06-18 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/10423 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/tripati2009/tripati2009.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/tripati2009/tripati2009.xls https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/tripati2009/tripati2009.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/tripati2009/tripati2009.xls English https://www.ncdc.noaa.gov/paleo/study/10423 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/tripati2009/tripati2009.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/tripati2009/tripati2009.xls Aradhna K. Tripati, Christopher D. Roberts, Robert A. Eagle2009Coupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 Million YearsScience32659581394-139710.1126/science.1178296http://science.sciencemag.org/content/326/5958/1394 START YEAR: 20000000 cal yr BP * END YEAR: 0 cal yr BP 159.35 -26 161 .32