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(5, CO events of down these initiate to required were (CO atmo- dioxide carbon that of 639– demonstrate concentrations and studies spheric 717–662 Climate-modeling 4). about (3, (Ma)] Ma ago 635 million –541 [1,000 the era experienced during occurred these Earth (2) of events history, recent Earth” most “Snowball long The glaciation. its planetary of In episodes several (1). decrease a gases or greenhouse radiation solar in incoming in reduction a by example, I CO atmospheric in variations driven orbitally corre- large carbon reveals dioxide organic carbon atmospheric of of (CO drawdown rate was significant burial today a with high fuel lates early 2017) fossil The and 7, Carboniferous July as periods. late review for the used Permian (received during 2017 deposits debris 5, plant coal September from approved Earth’s formed and CA, of Jolla, La bulk Diego, The San California, of University Thiemens, H. Mark by Edited a to Feulner close Georg Earth brought glaciation coal global our of most of Formation osa nttt o lmt matRsac,LinzAscain –47 osa,Germany Potsdam, D–14473 Association, Leibniz Research, Impact Climate for Institute Potsdam h lmt ytm lblgaito sarsl fteposi- the of for result initiated, a cooling runaway is causing glaciation feedback ice-albedo global tive system, climate the n h nyohreohwt iial o auso atmospheric of values low similarly with epoch other only The 2 2 tta ie eetaayi fahg-eouinrecord high-resolution a of analysis recent A time. that at ) ic hs lblgaitosocre ntePalaeozoic the in occurred glaciations global these since 8 n 0 p 1) uigteeris Permian earliest the During (18). ppm 300 and ∼180 | 2 Carboniferous a ensgetdt elne oicesdweath- increased to linked be to suggested been has a,1 2 0 acoet h onaybtenthe between boundary the to close Ma ∼300 2 5 n 0 p o h aetCarbonifer- latest the for ppm 700 and ∼150 uigti aePlezi c g (14). age ice Palaeozoic late this during 2 2 sn ope lmt oe.Tecold- The model. climate coupled a using concentrations | Permian ± 2 0pmfrteeris Permian. earliest the for ppm 80 | ausvr vrgailcycles glacial over vary values glaciation 0pm ugsiga suggesting ppm, <40 2 ocnrtosi the in concentrations | 2 below ) coal 0 ppm ∼100 5 and ∼150 2 con- 2 . ue uigeryNrhr umr(n otenhemisphere midlati- Northern hemisphere (and larger summer Southern of Northern in early because during radiation warmer tudes solar are obliquity of lower absorption with Cli- orbits. states eccentric more mate for the radiation to solar mean attributed annual be higher can eccentricity increasing with warming The (ω (e obliquity eccentricities are maximum hand, other by the on characterized configurations, coldest The spring. sphere is (e configuration ity orbital (ω obliquity warmest minimum The for orbit. reached eccen- elliptical increasing with its and of (obliquity) tricity axis rotational decreas- its with of warmer tilt gets ing mean period time global this during fixed, climate Earth’s conditions from boundary with range other latest temperatures all considerably and the CO vary ppm atmospheric Keeping 100 for 1). Permian (Fig. parameters temperatures orbital earliest Earth’s mean and global Carboniferous annual Simulated Climate Late-Carboniferous and Parameters time. with Orbital this at particular, glaciation in global of and, threshold configurations the to bound- orbital respect Carboniferous/Permian different the for around ary system a climate the and time condi- atmosphere, the for boundary fast tions a model—and model, sea-ice circulation dynamic/thermodynamic general ocean an (20–23) growth 25). late- (24, ice-sheet patterns the on precipitation or focused for primarily efforts have modeling Palaeozoic Earlier CO in investigated. changes atmospheric tematically to and Permian parameters earliest and orbital Carboniferous latest the and ing variations orbital CO late-Palaeozoic for low the evidence very this of Despite maximum 100 (14). a of glaciations with (19) coinciding values reached, lower are even Ma), (297–298 period hsatcei NSDrc Submission. 1 Direct PNAS a is article This interest. of conflict no declares author The paper. the wrote uhrcnrbtos ..dsge eerh efre eerh nlzddt,and data, analyzed research, performed research, designed G.F. contributions: Author mi:[email protected]. Email: trdi at’ oldpst n hshv mlctosfor implications have thus and policy. climate deposits carbon coal fossil Earth’s the in of stored importance climatic the glaciation highlight findings to global to of due close limit planet cooling our the the brought effect that greenhouse demonstrate diminished the the to in levels used dioxide is carbon sim- atmosphere for model climate estimates of recent combination and a ulations dioxide work, this carbon In atmospheric time. of that at drawdown result- significant ago), a years in million ing (359–299 during deposited period been Carboniferous has con- the today and warming Revolution global Industrial the to driving tributing coal the of bulk The Significance ee s ope lmt oe 2)cnitn of (26)—consisting model climate coupled a use I Here, 0 = ,adaprhlo asg uigNrhr hemi- Northern during passage perihelion a and .069), PNAS 2 ocnrtos h estvt fteciaedur- climate the of sensitivity the concentrations, | . oexplore to Methods) and (Materials Ma ∼300 coe 4 2017 24, October ,adprhlo uigbra autumn. boreal during perihelion and 0.01), −1.4 0 ilo er g.These ago. years million ∼300 | ◦ 22.0 = to C o.114 vol. ◦ +0.45 24.5 = 2 ,mxmmeccentric- maximum ), | a ee ensys- been never has o 43 no. ◦ ◦ ,salorbital small ), .I general, In C. | ± 11333–11337 0ppm 80 2 at

EARTH, ATMOSPHERIC, AND PLANETARY SCIENCES = 22.0° = 23.5° = 24.5°

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−1.4 −1.2 −1.0 −0.8 −0.6 −0.4 −0.2 0.0 0.2 0.4 Annual Global Mean Temperature (°C)

Fig. 1. Annual global mean temperature for different orbital parameters. Average near-surface temperatures are shown in polar coordinates as a function of orbital eccentricity e and precession angle ω for obliquity ε = 22.0◦ (A), ε = 23.5◦ (B), and ε = 24.5◦ (C). The month of perihelion passage is indicated in each diagram.

midlatitudes during early Northern winter) caused by the sur- spheric CO2 concentration in the model for a cold orbital con- plus of incident solar radiation for smaller axial tilts in the win- figuration with obliquity ω = 24.5◦ and orbital eccentricity e = 0. ter hemisphere together with the delayed melting of sea ice and The coldest climate state without global ice cover is reached for snow in the summer hemisphere. a CO2 concentration of 40 ppm at a very low annual global mean temperature of −8.9 ◦C. Global glaciation occurs at 35 ppm, the Late-Carboniferous Glacials and next lowest CO2 value tested in the simulations. Because of the To describe typical glacial and climate states dur- increased solar luminosity, this threshold for global glaciation ing the latest Carboniferous, simulations with the coldest and during the late Palaeozoic is considerably lower than during the warmest orbital configurations and more realistic CO2 concen- Neoproterozoic (5, 6). In addition, continental configuration and trations of 150 and 700 ppm have been performed. These val- vegetation cover influence the glaciation threshold. ues are indicative of the full range of individual CO2 estimates It is interesting to compare this simulated value for the criti- for late-Carboniferous glacials and interglacials (17). Even for a cal CO2 concentration with the empirical estimates for that time late-Carboniferous interglacial characterized by a relatively high (17); Fig. 3. Estimated CO2 levels during the latest Carbonif- atmospheric CO2 concentration of 700 ppm and the warmest erous are well above the glaciation threshold despite consider- orbital configuration, Earth’s climate is relatively cool with an able fluctuations on orbital time scales. During the earliest Per- annual global mean temperature of 12 ◦C. In reality, however, mian, however, the threshold for glaciation of the interglacial climate state is likely somewhat warmer than 37.5 ± 2.5 ppm is within the uncertainty range of the estimates in the simulation because I do not take the partial melting of of 100 ± 80 ppm. Note that the time resolution of the empir- the ice sheet and the increase in vegetation cover into account. ical estimates is insufficient to resolve orbital variations during Both effects would lower the albedo as compared with the glacial this time. It is likely that the atmospheric CO2 concentration in state and lead to further warming. For a low CO2 concentration the earliest Permian underwent orbitally driven fluctuations sim- of 150 ppm CO2 and the coldest orbital configuration, global ilar to the latest Carboniferous—where we have records with a mean temperatures are down to 1.4 ◦C. Regionally, the coldest sufficiently high temporal resolution (17)—or the past million temperatures are found over the Southern polar continent and years—where we can measure the variations from ice cores (18). its ice sheet (Fig. 2). In the western highlands of tropical Pan- In this sense, Earth’s escape from global glaciation during the gaea, annual mean temperatures are below the freezing point in earliest Permian can certainly be regarded as surprisingly nar- the glacial simulation, in line with evidence for upland glacia- row. Further CO2 drawdown (and thus a Snowball Earth state) tion in this region (28, 29). For comparison, global tempera- was most likely prevented by negative feedbacks limiting vegeta- tures over the most recent glacial cycles are estimated (30) to tion growth and weathering under the very cold and dry climatic have varied between ∼10 ◦C and 15 ◦C. The differences between conditions close to the global glaciation threshold. Indeed, water- glacial/interglacial temperature variations between the late Car- use efficiency of typical coal forest taxa has been shown to be boniferous and the Quaternary are largely due to the higher solar significantly reduced at low CO2 values (31), which could have constant today and the smaller range of changes in atmospheric contributed to the observed dieback of coal forests ∼300 Ma 87 86 CO2 over the recent glacial cycles. (32). Furthermore, declining Sr/ Sr strontium isotope ratios of seawater suggest a marked decrease in global weathering at Threshold for Global Glaciation that time (33). Finally, the sensitivity of the late-Palaeozoic climate system with The glaciation threshold derived here is most likely conser- respect to global glaciation is explored by lowering the atmo- vative because of two effects not considered in the simulations.

11334 | www.pnas.org/cgi/doi/10.1073/pnas.1712062114 Feulner Downloaded by guest on September 25, 2021 Downloaded by guest on September 25, 2021 Feulner major- the of formation 2 the to Ironically, increase (38). temperature value bud- preindustrial global carbon allowed limiting the for exceed would get alone reserves coal all CO ing the of and ppm, CO 29% 400 of Atmospheric surpassed for 41% (37). and responsible (36) that 2015 is in coal CO production anthropogenic energy fossil primary of global the burning the Today, Discussion values. reconstructed the to closer even the threshold raise would effects CO Both critical (10). from likely aerosols more stratospheric eruptions of volcanic injection low a the by making characterized are tropopause, states not climate (35). Cold are temper- account. eruptions radiation into volcanic air shortwave taken of surface effects of cooling reduced sporadic scattering the in increased Second, result to to due shown oxy- atures of been levels Enhanced have (34). gen oxygen atmospheric in maximum CO a atmospheric in minimum the First, CO of ppm 150 maps. both for in and resolution (A) original configuration the orbital at drawn warm are a (27) and continents ppm 700 of concentration i.2. Fig. nulma eprtr asfrlts-abnfru lcasaditrlcas aso nulma ersraetmeaue o CO a for temperatures near-surface mean annual of Maps interglacials. and glacials latest-Carboniferous for maps temperature mean Annual 2 ocnrto n ol hsbigteglaciation the bring thus would and concentration 2 msin rmfsi ul n nutyin industry and fuels fossil from emissions A Latitude B Latitude −90 −60 −30 −90 −60 −30 30 60 90 30 60 90 0 0 0 0 0 0 2 10 8 20 4 20 0 30360 330 300 270 240 210 180 150 120 90 60 30 0 360 330 300 270 240 210 180 150 120 90 60 30 0 2 2 msin eutn rmburn- from resulting emissions ocnrtoshv recently have concentrations 150 ppmCO 700 ppmCO 2 0 acicdswith coincides Ma ∼300 5 4 3 2 1 0 0 030 20 10 0 −10 −20 −30 −40 −50 2 2 , , ε ε ◦ =24.5°,e0.010, =22.0°,e0.069, bv the above C Annual MeanTemperature(°C) Longitude Longitude ru n h ema;vgtto oe specie olwn estimates following prescribed is cover vegetation Carbonif- Permian; the the between boundary a and the on erous to based close Ma, are 300 topography for and (27) distribution are reconstruction Land gen- (6) (5). atmosphere–ocean Neoproterozoic model coupled a circulation the from eral during results with states agreement par- excellent Earth in for in Snowball threshold states to glaciation climate global transition cold and the sensitivity for climate 45); simulated models (44, the other ticular, projects with well intercomparison compares model It tem- (43). in reconstructed millennium against last example, the for over it, peratures testing 22.5 studies, of paleoclimate resolution of spatial coarse 7.5 and a tude with (42) statistical–dynamical (39, model fast a MOM3 atmosphere and model (41), 3.75 circulation model of sea-ice general resolution dynamic/thermodynamic horizontal ocean a the at consisting of run (26) 40) version model modified climate coupled a a of with performed are simulations All Methods and Materials economies. industrialized further fossil our a of drive amounts glaciation, mostly vast still global the that of of carbon relevance threshold climatic the the of brought to illustration (15) Palaeozoic close late Earth the during the reserves coal these of ity ω ω =270° =45° 2 .Rcntutdcnor of contours Reconstructed (B). configuration orbital cold a and ◦ nlttd.Temdlhsbe ucsflyue nanumber a in used successfully been has model The latitude. in PNAS | coe 4 2017 24, October ◦ × 3.75 | o.114 vol. ◦ ih2 etcllvl,a levels, vertical 24 with | o 43 no. ◦ nlongi- in | 11335 2

EARTH, ATMOSPHERIC, AND PLANETARY SCIENCES Carboniferous Permian Quaternary glaciations Orbital variations resolved 800 (ppm)

2 600

400

Atmospheric CO 200

0 312 310 308 306 304 302 300 298 296 Age (Ma)

Fig. 3. Estimates of atmospheric CO2 and the global glaciation threshold ∼300 million years ago. Critical level of the CO2 concentration of 37.5 ± 2.5 ppm, below which Earth enters a fully glaciated state (cyan; this work), is compared with empirical estimates of the atmospheric CO2 level during the latest Carboniferous and earliest Permian (17) (black and gray shading indicates 2.5%/97.5% uncertainty ranges). Note that the temporal resolution of the empirical estimates is considerably lower before 308 Ma and after 301 Ma; in particular, orbital-scale fluctuations during the CO2 minimum at the beginning of the Permian are not resolved. The range of CO2 variations during the Quaternary (18) is indicated on the right-hand side.

(46) for climate zones at the time. An idealized elliptical ice sheet with a distribution unchanged). Finally, a set of simulations with fixed CO2 con- maximum height of h0 = 2000 m is placed on the polar continent in the centrations <100 ppm and the coldest orbital configuration tests the limit ◦ ◦ South, centered at longitude λ0 = 240 and latitude ϕ0 = −71.25 and of global glaciation. All simulations are integrated for at least 2,000 model ◦ 6 with an elevation distribution following h0 × (1 − [((λ − λ0)/122.5 ) + years until climate equilibrium is approached. The source code for the model ◦ 6 2 ((ϕ − ϕ0)/20.0 ) ]). The solar constant is set to 1,327 W/m based on the used in this study, the data and input files necessary to reproduce the exper- best estimate (47) for the present-day solar constant of 1,361 W/m2 and stan- iments, and model output data are available from the author upon request. dard solar evolution (48). Sensitivity to orbital parameters is investigated at All data are archived at the Potsdam Institute for Climate Impact Research. a fixed atmospheric CO2 concentration of 100 ppm and for obliquity values ε of 22.0◦, 23.5◦, 24.5◦, eccentricity values e of 0, 0.03, 0.069, and perihe- ACKNOWLEDGMENTS. I thank Christopher Scotese for providing his paleo- continental reconstruction in electronic form and Julia Brugger, as well as lion angles ω (defined relative to vernal equinox) ranging from 0◦ to 315◦ ◦ two anonymous reviewers for helpful comments. The European Regional in intervals of 45 for nonzero eccentricity. Two additional simulations char- Development Fund, the German Federal Ministry of Education and Research, acterize the extremes of climate variations through glacial cycles by using and the Land Brandenburg supported this project by providing resources on 700 ppm CO2 at the warmest orbital configuration and 150 ppm CO2 at the the high-performance computer system at the Potsdam Institute for Climate coldest orbital configuration (leaving sea-level, ice-sheet, and vegetation Impact Research.

1. Opik¨ EJ (1965) Climatic change in cosmic perspective. Icarus 4:289–307. 15. Thomas LJ (2012) Coal Geology (John Wiley & Sons, New York). 2. Kirschvink JL (1992) Late low-latitude global glaciation: The snowball 16. Nelsen MP, DiMichele WA, Peters SE, Boyce CK (2016) Delayed fungal evolution Earth. The Proterozoic Biosphere: A Multidisciplinary Study, eds Schopf JW, Klein C did not cause the Paleozoic peak in coal production. Proc Natl Acad Sci USA 113: (Cambridge Univ Press, Cambridge, UK), pp 51–52. 2442–2447. 3. Prave AR, Condon DJ, Hoffmann KH, Tapster S, Fallick AE (2016) Duration and nature 17. Montanez˜ IP, et al. (2016) Climate, pCO and terrestrial carbon cycle linkages during 2 of the end- (Marinoan) glaciation. Geology 44:631–634. late Palaeozoic glacial-interglacial cycles. Nat Geosci 9:824–828. 4. Rooney AD, et al. (2014) Re-Os geochronology and coupled Os-Sr isotope constraints 18. Siegenthaler U, et al. (2005) Stable carbon cycle-climate relationship during the late on the Sturtian snowball Earth. Proc Natl Acad Sci USA 111:51–56. Pleistocene. Science 310:1313–1317. 5. Liu Y, Peltier WR, Yang J, Vettoretti G (2013) The initiation of Neoproterozoic “snow- 19. Montanez˜ IP, et al. (2007) CO2-forced climate and vegetation instability during late ball” climates in CCSM3: The influence of paleocontinental configuration. Clim Past Paleozoic deglaciation. Science 315:87–91. 9:2555–2577. 20. Crowley TJ, Baum SK, Hyde WT (1991) Climate model comparison of Gondwanan and 6. Feulner G, Kienert H (2014) Climate simulations of Neoproterozoic snowball Earth Laurentide glaciations. J Geophys Res 96:9217–9226. events: Similar critical carbon dioxide levels for the Sturtian and Marinoan glaciations. 21. Hyde WT, Crowley TJ, Tarasov L, Peltier WR (1999) The Pangean : Studies with Earth Planet Sci Lett 404:200–205. a coupled climate-ice sheet model. Clim Dyn 15:619–629. 7. Hoffman PF, Schrag DP (2002) The snowball earth hypothesis: Testing the limits of 22. Horton DE, Poulsen CJ, Pollard D (2007) Orbital and CO2 forcing of late Paleozoic global change. Terra Nova 14:129–155. continental ice sheets. Geophys Res Lett 34:L19708. 8. Godderis´ Y, et al. (2003) The Sturtian ‘snowball’ glaciation: Fire and ice. Earth Planet 23. Horton DE, Poulsen CJ, Pollard D (2010) Influence of high-latitude vegetation feed- Sci Lett 211:1–12. backs on late Palaeozoic glacial cycles. Nat Geosci 3:572–577. 9. Feulner G, Hallmann C, Kienert H (2015) Snowball cooling after algal rise. Nat Geosci 24. Otto-Bliesner BL (1993) Tropical mountains and coal formation—a climate model 8:659–662. study of the Westphalian (306 MA). Geophys Res Lett 20:1947–1950. 10. Macdonald FA, Wordsworth R (2017) Initiation of snowball Earth with volcanic sulfur 25. Peyser CE, Poulsen CJ (2008) Controls on Permo-Carboniferous precipitation over aerosol emissions. Geophys Res Lett 44:1938–1946. tropical Pangaea: A GCM sensitivity study. Palaeogeogr Palaeoclimatol Palaeoecol 11. Feulner G (2012) The faint young sun problem. Rev Geophys 50:RG2006. 268:181–192. 12. Royer DL (2006) CO2-forced climate thresholds during the Phanerozoic. Geochim Cos- 26. Montoya M, et al. (2005) The earth system model of intermediate complexity mochim Acta 70:5665–5675. CLIMBER-3α. Part I: Description and performance for present-day conditions. Clim 13. Berner RA (2003) The long-term carbon cycle, fossil fuels and atmospheric composi- Dyn 25:237–263. tion. Nature 426:323–326. 27. Scotese CR (2014) Atlas of Permo-Carboniferous Paleogeographic Maps (Mollweide 14. Montanez˜ IP, Poulsen CJ (2013) The late Paleozoic ice age: An evolving paradigm. Projection), Maps 53–64, Volumes 4, the Late Paleozoic, PALEOMAP Atlas for ArcGIS Annu Rev Earth Planet Sci 41:629–656. (PALEOMAP Project, Evanston, IL).

11336 | www.pnas.org/cgi/doi/10.1073/pnas.1712062114 Feulner Downloaded by guest on September 25, 2021 Downloaded by guest on September 25, 2021 4 enrR,e l 20)Iooefatoainadamshrcoye:Implications oxygen: atmospheric and fractionation Isotope (2000) al. et RA, Berner 34. 5 ole J ao ,WieJ 21)Ln-emciaefrigb topei oxy- atmospheric by forcing climate Long-term (2015) JD White C, Tabor CJ, Poulsen 35. (1999) al. global et on effect J, their Veizer and rainforests 33. tropical Palaeozoic (2005) BA Thomas plant CJ, of Cleal views 32. New forests: tropical Carboniferous Dynamic (2017) al. et JP, Wilson 31. archives. Paleoclimate from Information (2013) al. et V, Pangaea: Masson-Delmotte tropical 30. in glaciation Upland (2014) tropics. NG Heavens Pangaean DE, the Sweet in GS, cold Soreghan Anomalous 29. (2008) al. et GS, Soreghan 28. 8 cld ,EisP(05 h egahcldsrbto ffsi ul nsdwhen unused fuels fossil of distribution geographical The (2015) P Ekins C, McGlade 38. Qu Le 37. (2016) BP 36. Feulner o hnrzi O Phanerozoic for Geol Chem e concentrations. gen present? the to key the past the Is climates: climate. of forcing physiological 1353. for potential eds and Change, function the Climate to UK). on Cambridge, I Press, Panel Group Univ Intergovernmental (Cambridge Working al. the et of TF, of Stocker Contribution Report Basis. Assessment Science Fifth Physical The modeling. 2013: Change climate Paleozoic late for implications 122:137–163. and evidence Geologic 659–662. iiiggoa amn o2 to warming global limiting er ´ ,e l 21)Goa abnbde 2016. budget carbon Global (2016) al. et C, e ´ PSaitclRve fWrdEeg ue2016 June Energy World of Review Statistical BP 161:59–88. 2 evolution. Science 87 Sr/ 86 348:1238–1241. Sr, ◦ Science C. δ Nature 13 and C 287:1630–1633. 517:187–190. δ Geobiology 18 vlto fPaeoocseawater. Phanerozoic of evolution O at ytSiData Sci Syst Earth 3:13–31. B,London). (BP, e Phytol New 8:605–649. Geology 215:1333– Climate Geol J 36: 8 acl N isneutM,Bs 20)Slrmdl:Creteohadtime and epoch Current models: Solar and (2001) Evidence S irradiance: Basu solar MH, total of Pinsonneault value JN, lower Bahcall new, 48. A (2011) JL Lean G, Kopp 47. (2013) CR Scotese An X, reversibility: Chen AJ, and Boucot commitment change 46. climate Long-term (2013) al. et intercom- K, An Zickfeld experiments: model 45. climate idealized irradi- and Historical solar (2013) Minimum al. et Maunder M, for Eby estimates recent 44. most the Are (2011) G Feulner com- 43. intermediate of model system climate A CLIMBER-2: (2000) al. the et to V, Petoukhov model ice 42. sea global a of Sensitivity (1997) MA Maqueda Morales moments T, second-order Fichefet a of 41. Performance (2006) MA Maqueda Morales M, Hofmann (1999) 40. SM Griffies RC, Pacanowski 39. eedne,nurns n eisimlgclproperties. helioseismological 1012. and neutrinos, dependences, significance. climate 11. for Vol (Society OK), Paleontology Tulsa, and Geology, Sedimentology Sedimentary in Concepts SEPM Climate, of Indicators intercomparison. EMIC complexity. intermediate of models system earth of parison reconstructions? temperature with agreement in ance climate. present for performance and 1–17. description Model I: Part plexity. dynamics. and 12646. thermodynamics ice of treatment model. circulation general ocean an in scheme advection Princeton). Laboratory, Dynamics PNAS epy e Lett Res Geophys Clim J | 26:5782–5809. coe 4 2017 24, October hnrzi aeciae nAlso Lithologic of Atlas An Paleoclimate: Phanerozoic h O- Manual MOM-3 The 38:L01706. epy e Oceans Res Geophys J | o.114 vol. epy e Lett Res Geophys epy Res Geophys J NA/epyclFluid (NOAA/Geophyical lmPast Clim srpy J Astrophys | o 43 no. 9:1111–1140. lmDyn Clim 111:C05006. 38:L16706. 102:12609– | 555:990– 11337 16:

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