Abstract
The dry continental interior of Asia has remained arid throughout most of its geological history, yet the future of this unique ecosystem remains unclear. Here we use palynological and isotopic records to track vegetation and moisture throughout the warm early Eocene (57 to 44 million years ago) as an analogue for extreme atmospheric CO2 scenarios. We show that rainfall temporarily doubled and replaced the regional steppe by forested ecosystems. By reconstructing the season of pedogenic carbonate growth, we constrain the soil hydrologic regime and show that most of this rainfall occurred during the summer season. This humid event is therefore attributed to an inland expansion of monsoonal moisture following the massive greenhouse gas release of the Palaeocene–Eocene Thermal Maximum as identified by a negative carbon isotope excursion. The resulting abrupt greening of the Central Asian steppe-desert would have enabled mammal dispersal and could have played a role in carbon cycle feedbacks by enhancing soil organic carbon burial and silicate weathering. These extreme Eocene proto-monsoons, albeit different from the topography-driven Asian monsoon today, highlight the potential for abrupt shifts in Central Asian rainfall and ecosystems under future global warming.
This is a preview of subscription content, access via your institution
Access options
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$29.99 / 30 days
cancel any time
Subscribe to this journal
Receive 12 print issues and online access
$259.00 per year
only $21.58 per issue
Buy this article
- Purchase on SpringerLink
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
Data availability
Palynology counts, TOC and bulk organic δ13C, n-alkane δ13C and δ2H, XRD bulk mineralogy and carbonate δ13C, δ18O and Δ47 are available at https://doi.org/10.1594/PANGAEA.962894. The DeepMIP pre-industrial and Eocene climate model simulations are available by following the instructions at https://www.deepmip.org/data-eocene/. The weather station data from Xining and Tashkent are available at https://www.ncei.noaa.gov/products/wmo-climate-normals.
References
Barbolini, N. et al. Cenozoic evolution of the steppe-desert biome in Central Asia. Sci. Adv. 6, eabb8227 (2020).
Li, C. et al. Drivers and impacts of changes in China’s drylands. Nat. Rev. Earth Environ. 2, 858–873 (2021).
Cramwinckel, M. J. et al. Global and zonal‐mean hydrological response to early Eocene warmth. Paleoceanogr. Paleoclimatol. https://doi.org/10.1029/2022PA004542 (2023).
Westerhold, T. et al. An astronomically dated record of Earth’s climate and its predictability over the last 66 million years. Science 369, 1383–1387 (2020).
Abels, H. A. et al. Environmental impact and magnitude of paleosol carbonate carbon isotope excursions marking five early Eocene hyperthermals in the Bighorn Basin, Wyoming. Clim. Past 12, 1151–1163 (2016).
McInerney, F. A. & Wing, S. L. The Paleocene–Eocene Thermal Maximum: a perturbation of carbon cycle, climate, and biosphere with implications for the future. Annu. Rev. Earth Planet. Sci. 39, 489–516 (2011).
Zeebe, R. E. & Lourens, L. J. Solar System chaos and the Paleocene–Eocene boundary age constrained by geology and astronomy. Science 365, 926–929 (2019).
Rae, J. W. et al. Atmospheric CO2 over the past 66 million years from marine archives. Annu. Rev. Earth Planet. Sci. 49, 609–641 (2021).
Bougeois, L. et al. Asian monsoons and aridification response to Paleogene sea retreat and Neogene westerly shielding indicated by seasonality in Paratethys oysters. Earth Planet. Sci. Lett. 485, 99–110 (2018).
Caves Rugenstein, J. K. & Chamberlain, C. P. The evolution of hydroclimate in Asia over the Cenozoic: a stable-isotope perspective. Earth Sci. Rev. 185, 1129–1156 (2018).
Zhisheng, A., Kutzbach, J. E., Prell, W. L. & Porter, S. C. Evolution of Asian monsoons and phased uplift of the Himalaya–Tibetan plateau since late Miocene times. Nature 411, 62–66 (2001).
Molnar, P., Boos, W. R. & Battisti, D. S. Orographic controls on climate and paleoclimate of Asia: thermal and mechanical roles for the Tibetan Plateau. Annu. Rev. Earth Planet. Sci. https://doi.org/10.1146/annurev-earth-040809-152456 (2010).
Sun, X. & Wang, P. How old is the Asian monsoon system?—Palaeobotanical records from China. Palaeogeogr. Palaeoclimatol. Palaeoecol. 222, 181–222 (2005).
Wu, F. et al. Reorganization of Asian climate in relation to Tibetan Plateau uplift. Nat. Rev. Earth Environ. 3, 684–700 (2022).
Huber, M. & Goldner, A. Eocene monsoons. J. Asian Earth Sci. 44, 3–23 (2012).
Licht, A. et al. Asian monsoons in a late Eocene greenhouse world. Nature 513, 501–506 (2014).
Quan, C. et al. Revisiting the Paleogene climate pattern of East Asia: a synthetic review. Earth Sci. Rev. 139, 213–230 (2014).
Farnsworth, A. et al. Past East Asian monsoon evolution controlled by paleogeography, not CO2. Sci. Adv. 5, eaax1697 (2019).
Spicer, R. A. et al. Asian Eocene monsoons as revealed by leaf architectural signatures. Earth Planet. Sci. Lett. 449, 61–68 (2016).
Zhang, Z. et al. Early Eocene Asian climate dominated by desert and steppe with limited monsoons. J. Asian Earth Sci. 44, 24–35 (2012).
Tardif, D. et al. Orbital variations as a major driver of climate and biome distribution during the greenhouse to icehouse transition. Sci. Adv. 7, eabh2819 (2021).
Li, Q. et al. Monsoonal climate of East Asia in Eocene times inferred from an analysis of plant functional types. Palaeogeogr. Palaeoclimatol. Palaeoecol. 601, 111138 (2022).
Meijer, N. et al. Central Asian moisture modulated by proto-Paratethys Sea incursions since the early Eocene. Earth Planet. Sci. Lett. 510, 73–84 (2019).
Stein, R. A., Sheldon, N. D. & Smith, S. Y. Soil carbon isotope values and paleoprecipitation reconstruction. Paleoceanogr. Paleoclimatol. 36, e2020PA004158 (2021).
Breecker, D. O., Sharp, Z. D. & McFadden, L. D. Seasonal bias in the formation and stable isotopic composition of pedogenic carbonate in modern soils from central New Mexico, USA. Geol. Soc. Am. Bull. 121, 630–640 (2009).
Kelson, J. R. et al. A proxy for all seasons? A synthesis of clumped isotope data from Holocene soil carbonates. Quat. Sci. Rev. 234, 106259 (2020).
Page, M. et al. Synchronous cooling and decline in monsoonal rainfall in northeastern Tibet during the fall into the Oligocene icehouse. Geology 47, 203–206 (2019).
Licht, A. et al. Dynamics of pedogenic carbonate growth in the tropical domain of Myanmar. Geochem. Geophys. Geosyst. 23, e2021GC009929 (2022).
Licht, A. et al. Decline of soil respiration in northeastern Tibet through the transition into the Oligocene icehouse. Palaeogeogr. Palaeoclimatol. Palaeoecol. 560, 110016 (2020).
Meijer, N. et al. Early Eocene magnetostratigraphy and tectonic evolution of the Xining Basin, NE Tibet. Basin Res. https://doi.org/10.1111/bre.12720 (2023).
Chen, Z., Ding, Z., Tang, Z., Wang, X. & Yang, S. Early Eocene carbon isotope excursions: evidence from the terrestrial coal seam in the Fushun Basin, Northeast China. Geophys. Res. Lett. 41, 3559–3564 (2014).
Chen, Z. et al. Structure of the carbon isotope excursion in a high-resolution lacustrine Paleocene–Eocene Thermal Maximum record from central China. Earth Planet. Sci. Lett. 408, 331–340 (2014).
Kohn, M. J. Carbon isotope compositions of terrestrial C3 plants as indicators of (paleo) ecology and (paleo) climate. Proc. Natl Acad. Sci. USA 107, 19691–19695 (2010).
Diefendorf, A. F., Mueller, K. E., Wing, S. L., Koch, P. L. & Freeman, K. H. Global patterns in leaf 13C discrimination and implications for studies of past and future climate. Proc. Natl Acad. Sci. USA 107, 5738–5743 (2010).
Chen, Z. et al. Spatial change of precipitation in response to the Paleocene–Eocene thermal Maximum warming in China. Glob. Planet. Change 194, 103313 (2020).
Beckner, J. R. & Mozley, P. S. in Carbonate Cementation in Sandstones: Distribution Patterns and Geochemical Evolution (ed. Morad, S.) 27–51 (Wiley, 1998); https://doi.org/10.1002/9781444304893.ch2
Warren, J. Dolomite: occurrence, evolution and economically important associations. Earth Sci. Rev. 52, 1–81 (2000).
Eiler, J. M. “Clumped-isotope” geochemistry—the study of naturally-occurring, multiply-substituted isotopologues. Earth Planet. Sci. Lett. 262, 309–327 (2007).
Lunt, D. J. et al. DeepMIP: model intercomparison of early Eocene Climatic Optimum (EECO) large-scale climate features and comparison with proxy data. Climate 17, 203–227 (2021).
Molnar, P. Differences between soil and air temperatures: implications for geological reconstructions of past climate. Geosphere 18, 800–824 (2022).
Hough, B. G. et al. Stable isotope evidence for topographic growth and basin segmentation: implications for the evolution of the NE Tibetan Plateau. Geol. Soc. Am. Bull. 123, 168–185 (2011).
Inglis, G. N. et al. Global mean surface temperature and climate sensitivity of the early Eocene Climatic Optimum (EECO), Paleocene–Eocene Thermal Maximum (PETM), and latest Paleocene. Clim. Past 16, 1953–1968 (2020).
Chenggao, G. & Renaut, R. W. The effect of Tibetan uplift on the formation and preservation of Tertiary lacustrine source-rocks in eastern China. J. Paleolimnol. 11, 31–40 (1994).
Wang, B., Kim, H.-J., Kikuchi, K. & Kitoh, A. Diagnostic metrics for evaluation of annual and diurnal cycles. Clim. Dyn. 37, 941–955 (2011).
Dupont-Nivet, G. et al. Tibetan plateau aridification linked to global cooling at the Eocene–Oligocene transition. Nature 445, 635–638 (2007).
Bowen, G. J. et al. Mammalian dispersal at the Paleocene/Eocene boundary. Science 295, 2062–2065 (2002).
Chaimanee, Y. et al. Late middle Eocene primate from Myanmar and the initial anthropoid colonization of Africa. Proc. Natl Acad. Sci. USA 109, 10293–10297 (2012).
Robin-Champigneul, F. et al. Northward expansion of the southern-temperate podocarp forest during the early Eocene: palynological evidence from the NE Tibetan Plateau (China). Rev. Paleobot. Palynol. https://doi.org/10.1016/j.revpalbo.2023.104914 (2023).
Fang, X. et al. Paleogene global cooling–induced temperature feedback on chemical weathering, as recorded in the northern Tibetan Plateau. Geology 47, 992–996 (2019).
Aminov, J., Dupont-Nivet, G., Ruiz, D. & Gailleton, B. Paleogeographic reconstructions using QGIS: introducing Terra Antiqua plugin and its application to 30 and 50 Ma maps. Earth Sci. Rev. https://doi.org/10.1016/j.earscirev.2023.104401 (2023).
MacDiff (Univ. College London, 1997); http://mill2.chem.ucl.ac.uk/ccp/web-mirrors/krumm/html/software/macdiff.html
Rohrmann, A. et al. Miocene orographic uplift forces rapid hydrological change in the southern central Andes. Sci. Rep. 6, 35678 (2016).
Bernasconi, S. et al. InterCarb: a community effort to improve interlaboratory standardization of the carbonate clumped isotope thermometer using carbonate standards. Geochem. Geophys. Geosyst. 22, e2020GC009588 (2021).
Daëron, M. Full propagation of analytical uncertainties in Δ47 measurements. Geochem. Geophys. Geosyst. 22, e2020GC009592 (2021).
Anderson, N. T. et al. A unified clumped isotope thermometer calibration (0.5–1100 °C) using carbonate-based standardization. Geophys. Res. Lett. 48, e2020GL092069 (2021).
Kim, S.-T. & O’Neil, J. R. Equilibrium and nonequilibrium oxygen isotope effects in synthetic carbonates. Geochim. Cosmochim. Acta 61, 3461–3475 (1997).
Araguás-Araguás, L., Froehlich, K. & Rozanski, K. Stable isotope composition of precipitation over Southeast Asia. J. Geophys. Res. 103, 28721–28742 (1998).
Horowitz, A. Palynology of Arid Lands (Elsevier, 1992).
Dupont-Nivet, G., Hoorn, C. & Konert, M. Tibetan uplift prior to the Eocene–Oligocene Climate Transition: evidence from pollen analysis of the Xining Basin. Geology 36, 987–990 (2008).
Hoorn, C. et al. A late Eocene palynological record of climate change and Tibetan plateau uplift (Xining Basin, China). Palaeogeogr. Palaeoclimatol. Palaeoecol. 344–345, 16–38 (2012).
Wynn, J. G. Carbon isotope fractionation during decomposition of organic matter in soils and paleosols: implications for paleoecological interpretations of paleosols. Palaeogeogr. Palaeoclimatol. Palaeoecol. 251, 437–448 (2007).
Diefendorf, A. F. & Freimuth, E. J. Extracting the most from terrestrial plant-derived n-alkyl lipids and their carbon isotopes from the sedimentary record: a review. Org. Geochem. 103, 1–21 (2017).
Tipple, B. J., Meyers, S. R. & Pagani, M. Carbon isotope ratio of Cenozoic CO2: a comparative evaluation of available geochemical proxies. Paleoceanogr. Paleoclimatol. https://doi.org/10.1029/2009PA001851 (2010).
Mack, G. H., Cole, D. R. & Treviño, L. The distribution and discrimination of shallow, authigenic carbonate in the Pliocene–Pleistocene Palomas Basin, southern Rio Grande rift. Geol. Soc. Am. Bull. 112, 643–656 (2000).
Quade, J. et al. Soils at the hyperarid margin: the isotopic composition of soil carbonate from the Atacama Desert, Northern Chile. Geochim. Cosmochim. Acta 71, 3772–3795 (2007).
Regional Geological Survey Reports of Ledu Sheet (1:200000), Qinghai Province, P.R. China (Bureau of Geological and Mineral Resources of Qinghai Province, 1965).
Last, W. M. Lacustrine dolomite—an overview of modern, Holocene, and Pleistocene occurrences. Earth Sci. Rev. 27, 221–263 (1990).
Peterson, M. N. A., Bien, G. S. & Berner, R. A. Radiocarbon studies of recent dolomite from Deep Spring Lake, California. J. Geophys. Res. 68, 6493–6505 (1963).
Wolfbauer, C. A. & Surdam, R. C. Origin of nonmarine dolomite in Eocene Lake Gosiute, Green River Basin, Wyoming. Geol. Soc. Am. Bull. 85, 1733–1740 (1974).
Remy, R. R. & Ferrell, R. E. Distribution and origin of analcime in marginal lacustrine mudstones of the Green River Formation, south-central Uinta Basin, Utah. Clays Clay Miner. 37, 419–432 (1989).
Fang, X. et al. An Eocene–Miocene continuous rock magnetic record from the sediments in the Xining Basin, NW China: indication for Cenozoic persistent drying driven by global cooling and Tibetan Plateau uplift. Geophys. J. Int. 201, 78–89 (2015).
Lepre, C. J. & Olsen, P. E. Hematite reconstruction of Late Triassic hydroclimate over the Colorado Plateau. Proc. Natl Acad. Sci. USA 118, e2004343118 (2021).
Müller, R. D., Royer, J. Y. & Lawver, L. A. Revised plate motions relative to the hotspots from combined Atlantic and Indian Ocean hotspot tracks. Geology 21, 275–278 (1993).
ODSN (GEOMAR, 2014); https://www.odsn.de/odsn/services/paleomap/paleomap.html
Herold, N. et al. A suite of early Eocene (∼5 Ma) climate model boundary conditions. Geosci. Model Dev. 7, 2077–2090 (2014).
Laskar, J., Fienga, A., Gastineau, M. & Manche, H. La2010: a new orbital solution for the long-term motion of the Earth. Astron. Astrophys. 532, A89 (2011).
Acknowledgements
This study was funded by an ERC consolidator grant (MAGIC 649081 to G.D.-N.) and through the VeWA consortium by the LOEWE programme of the Hessen Ministry of Higher Education, Research and the Arts, Germany. We thank R. Petschick for help with the XRD analyses as well as J. McCormack and A. Davies for suggestions on the formation of dolomite. We acknowledge R. Erkens and the following students from Maastricht University for their help in exploring the palynological samples: H. del Marmol, L. Sauerschnig, K. de Jong, A. Villagrasa, L. Licht, H. de Schrevel and B. Diana. We also acknowledge H. van den Hill (University of Amsterdam) and J. Gravendeyk (University of Bonn) for extensive sporomorph documentation. We thank H. Meyer for kindly providing organic stable isotope analyses and A. Ballian, S. Hofmann and S. Anderson for assistance with stable and clumped isotope analyses. We also thank C. Günter and U. Altenberger for their help with the SEM and CL. We are grateful to N. Barbolini, X.-J. Liu, X. Wu, Z. Wu, M. Xiao and Y. Zhang for their support with collecting the samples. We also acknowledge the efforts of the DeepMIP community and are thankful for the available climate model simulation data.
Author information
Authors and Affiliations
Contributions
N.M., A.L. and G.D.-N. designed the study. N.M., A.L., A.W., A.R., A.S. and G.D.-N. conducted the fieldwork and collected the samples. N.M. performed the XRD and petrographic analyses. A.W., F.R.-C. and C.H. prepared and analysed the palynological samples. A.R. and M.T.H. performed the n-alkane analyses. N.M., A.L., A.J.S. and A.M. conducted the stable isotope analyses. N.M., M.T. and J.F. performed the clumped isotope analyses. J.B. and F.D.K. analysed and plotted the climate model simulation data. N.M. wrote the paper with major input from A.L., G.D.-N. and A.M. All co-authors contributed to interpreting the data and writing the paper.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Peer review
Peer review information
Nature Geoscience thanks the anonymous reviewers for their contribution to the peer review of this work. Primary Handling Editor: James Super, in collaboration with the Nature Geoscience team.
Additional information
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Extended data
Extended Data Fig. 1 Pre-industrial control simulations and weather station data from the Xining Basin.
Weather station precipitation data (https://www.ncei.noaa.gov/products/wmo-climate-normals) and pre-industrial control simulations of A) temperature and B) precipitation in the Xining Basin using the DeepMIP climate model ensemble.
Extended Data Fig. 2 Carbon isotope values versus TOC.
Soil organic matter δ13C versus Total Organic Content (TOC).
Extended Data Fig. 3 XRD.
XRD diffractograms showing the dominant peaks and bulk mineralogy of selected samples including: a dolomite bed (CjC9, as shown on Extended Data Fig. 4G; composite position: -37.1 m), a calcareous mudrock (16Cj237.5; composite position: 193 m), a calcareous mudrock from the CIE interval (18Ld-16; composite position: -31m) and a dolomitic mudrock (15Cj79; composite position: 54 m). The samples 16Cj237.5 and 18Ld-16 were used for stable and clumped isotope analyses.
Extended Data Fig. 4 Microscope and field photographs.
A) and B) Cross-polarized and cathodoluminescence image of a mudrock sample with vadose-grown calcite cement (18LD-15; Ledu section; -15 meter-level) showing silt-sized matrix with dispersed organic matter, dull luminescent micrite and some luminescent microsparite and sparite. Plane-polarized images of pedogenic nodules showing: C) Micrite matrix with floating detrital grains in 18LD+4nodB (Ledu section; 12.3 meter-level). D) Floating detrital grains with isopachous microsparite to sparite rim and micritic matrix in 18LDconglonod (Ledu section; -60 meter-level). Massive red dolomitic mudrock samples showing rhombohedral dolomite crystals in E) plane-polarized light (15CJ-111_75; Caijia section 131.25 meter-level) and F) SEM (15CJ-112_5; Caijia section; 132 meter-level). G) Greenish lacustrine mudrocks interbedded with massive dolomite beds (Caijia section; 75 meter-level), hammer for scale. H) Dolomite-filled burrow (Caijia section; 93 meter-level).
Extended Data Fig. 5 Carbonate and plant wax stable isotopes.
Stable isotope record (δ18Ocarb and δ13Ccarb) of the vadose-grown and pedogenic carbonates and δ2Hwax values of plant waxes. δ18O values of the soil water (δ18Owater) are reconstructed using the Δ47-derived temperatures. Modern-day δ18Owater values of the summer monsoon and wintertime westerlies are shown57.
Extended Data Fig. 6 Carbonate stable isotope biplot.
Stable isotope biplot of the studied calcites.
Extended Data Fig. 7 Monsoonal domains in DeepMIP climate model simulations.
Distribution of monsoonal domains in the pre-industrial control and 3x pCO2 Eocene DeepMIP simulations. Summer (MJJAS) minus winter precipitation (NDJFM) is used as a metric and regions where this difference is > 2.5 mm/day are considered monsoonal44. Red dot indicates the location of the Xining Basin.
Extended Data Fig. 8 Timing of Xining CIE compared with CENOGRID and astronomical solutions.
CENOGRID showing the evolution of benthic foraminifera stable isotope values4. The δ18O values show peak warmth of the EECO and the δ13C values show several hyperthermal events characterized by negative CIE’s. The astronomical solutions76 show the evolution of the eccentricity of Earth’s orbit. The radiometric ages bracketing the CIE in the Xining Basin are indicated.
Extended Data Fig. 9 Summer sea-level atmospheric pressure anomalies in DeepMIP climate model simulations.
Sea-level atmospheric pressure anomalies during summer (JJA) in the 6x pCO2 Eocene and the pre-industrial control simulations of the DeepMIP ensemble. Red dot indicates the location of the Xining Basin.
Supplementary information
Supplementary Data 1
Palynological counts.
Supplementary Data 2
Bulk organic data.
Supplementary Data 3
n-Alkanes.
Supplementary Data 4
MAP reconstruction.
Supplementary Data 6
Carbonate stable isotope data and summary of clumped isotopes.
Supplementary Data 7
Clumped isotope data.
Rights and permissions
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
About this article
Cite this article
Meijer, N., Licht, A., Woutersen, A. et al. Proto-monsoon rainfall and greening in Central Asia due to extreme early Eocene warmth. Nat. Geosci. 17, 158–164 (2024). https://doi.org/10.1038/s41561-023-01371-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41561-023-01371-4