Global and regional temperature change over the past 4.5 million years

Clark, Peter U.; Shakun, Jeremy D.; Rosenthal, Yair; Köhler, Peter; Bartlein, Patrick J.

doi:10.1126/science.adi1908

Cited by 22 publications

(6 citation statements)

References 223 publications

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“…S6, and table S2). A recent stack of extratropical SST for the two hemispheres ( 25 ) shares great similarity with our hemispheric SST stacks. Both the extratropical and our hemispheric SST stacks indicate that cooling of the SH prior to the MPT preceded that of the NH (fig.…”

Section: Reconstructed Bipolar Ice Sheetssupporting

confidence: 76%

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Mid-Pleistocene climate transition triggered by Antarctic Ice Sheet growth

An,

Zhou,

Zhang

et al. 2024

Science

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Despite extensive investigation, the nature and causes of the Mid-Pleistocene Transition remain enigmatic. In this work, we assess its linkage to asynchronous development of bipolar ice sheets by synthesizing Pleistocene mid- to high-latitude proxy records linked to hemispheric ice sheet evolution. Our results indicate substantial growth of the Antarctic Ice Sheets (AISs) at 2.0 to 1.25 million years ago, preceding the rapid expansion of Northern Hemisphere Ice Sheets after ~1.25 million years ago. Proxy-model comparisons suggest that AIS and associated Southern Ocean sea ice expansion can induce northern high-latitude cooling and enhanced moisture transport to the Northern Hemisphere, thus triggering the Mid-Pleistocene Transition. The dynamic processes involved are crucial for assessing modern global warming that is already inducing asynchronous bipolar melting of ice sheets.

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Section: Reconstructed Bipolar Ice Sheetssupporting

confidence: 76%

“…Applying a larger age uncertainty (4 to 6 kyr) could reduce the estimates of glacial ice volume before ~1.25 Ma disproportionately (fig. S9), a finding also noted in the recent SST stacking ( 25 ).…”

Section: Reconstructed Bipolar Ice Sheetssupporting

confidence: 71%

Mid-Pleistocene climate transition triggered by Antarctic Ice Sheet growth

An,

Zhou,

Zhang

et al. 2024

Science

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“…Climate records off southern Greenland, however, suggest MIS 9 (Irvalı et al, 2020) or MIS 5e (Cluett & Thomas, 2021) were exceptionally warm. A recent temperature reconstruction suggests global warmth was similar during MIS 11 and MIS 5e (Clark et al, 2024). These studies highlight discrepancies among records and regions on which interglacial was warmest, and it remains unclear how climates during past interglacials affected other high-latitude continental regions.…”

Section: Introductionmentioning

confidence: 88%

Insights Into Changing Interglacial Conditions in Subarctic Canada From MIS 11 Through MIS 5e From Seasonally Resolved Speleothem Records

Batchelor,

McGee,

Shakun

et al. 2024

Geophysical Research Letters

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High‐resolution records from past interglacial climates help constrain future responses to global warming, yet are rare. Here, we produce seasonally resolved climate records from subarctic‐Canada using micron‐scale measurements of oxygen isotopes (δ18O) in speleothems with apparent annual growth bands from three interglacial periods—Marine Isotope Stages (MIS) 11, 9, and 5e. We find 3‰ lower δ18O values during MIS 11 than MIS 5e, despite MIS 11 likely being warmer. We explore controls on high‐latitude speleothem δ18O and suggest low MIS 11 δ18O values reflect greater contribution of cold‐season precipitation to dripwater from longer annual ground thaw durations. Other potential influences include changes in precipitation source and/or increased fraction of cold‐season precipitation from diminished sea ice in MIS 11. Our study highlights the potential for high‐latitude speleothems to yield detailed isotopic records of Northern Hemisphere interglacial climates beyond the reach of Greenland ice cores and offers a framework for interpreting them.

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“…In addition, while these results are specific to the adapted S16 algorithm applied to the J20, we expect that the general concepts discussed here hold for any aggregation algorithm and dataset. In particular, the algorithm could be used for regional reconstructions (as done in Clark et al, 2024), as long as a sufficiently high number of records are considered. We suggest, for https://doi.org/10.5194/egusphere-2024-1387 Preprint.…”

Section: Quality Of the Reconstructionmentioning

confidence: 99%

“…Many methods for reconstructing the GMST use a bottom-up approach, where a large number of local proxy temperature records are combined to compute area-averaged temperature (e.g. Shakun et al, 2012;Snyder, 2016;Friedrich and Timmermann, 2020;Osman et al, 2021;Clark et al, 2024). This approach aims at suppressing noise and regional influences in these time series but remains sensitive to the spatial and temporal coverage of the data.…”

Section: Introductionmentioning

confidence: 99%

Testing the reliability of global surface temperature reconstructions of the last glacial cycle

Baudouin,

Weitzel,

May

et al. 2024

Preprint

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Abstract. Reconstructing past variations of the global mean surface temperature is used to characterise the Earth system response to perturbations as well as validate Earth system simulations. Reconstructing GMST beyond the instrumental period relies on algorithms aggregating local proxy temperature records. Here, we propose to establish standards for the evaluation of the performance of such reconstruction algorithms. Our framework relies on pseudo-proxy experiments. That is, we test the ability of the algorithm to reconstruct a simulated GMST, using artificially generated proxy data created from the same simulation. We apply the framework to an adapted version of the GMST reconstruction algorithm used in Snyder (2016), and the synthesis of marine proxy records for temperature of the last 130 kyr from Jonkers et al. (2020). We use an ensemble of 4 transient simulations of the last glacial cycle or the last 25 kyr for the pseudo-proxy experiments. We find the algorithm to be able to reconstruct timescales longer than 4 kyr over the last 25 kyr. However, beyond 40 kyr BP, age uncertainty limits the algorithm capability to timescales longer than 15 kyr. The main sources of uncertainty are a factor, that rescales near global mean sea surface temperatures to GMST, the proxy measurement, the specific set of record locations, and potential seasonal bias. Increasing the number of records significantly reduces all sources of uncertainty but the scaling. We also show that a trade-off exists between the inclusion of a large number of records, which reduces the uncertainty on long time scales, and of only records with low age uncertainty, high accumulation rate, and high resolution, which improves the reconstruction of the short timescales. Finally, the method and the quantitative results presented here can serve as a basis for future evaluations of reconstructions. We also suggest future avenues to improve reconstruction algorithms and discuss the key limitations arising from the proxy data properties.

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Global and regional temperature change over the past 4.5 million years

Cited by 22 publications

References 223 publications

Mid-Pleistocene climate transition triggered by Antarctic Ice Sheet growth

Mid-Pleistocene climate transition triggered by Antarctic Ice Sheet growth

Insights Into Changing Interglacial Conditions in Subarctic Canada From MIS 11 Through MIS 5e From Seasonally Resolved Speleothem Records

Testing the reliability of global surface temperature reconstructions of the last glacial cycle

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