Zonal Indian Ocean Variability Drives Millennial‐Scale Precipitation Changes in Northern Madagascar
Name
Paleoceanog and Paleoclimatol - 2023 - Tiger - Zonal Indian Ocean Variability Drives Millennial‐Scale Precipitation Changes.pdf
Description
Published version
Size
2.14 MB
Format
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Checksum (MD5)
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Author(s)
Tiger, Benjamin H
Burns, Stephen
Dawson, Robin R
Scroxton, Nick
Godfrey, Laurie R
Ranivoharimanana, Lovasoa
Faina, Peterson
McGee, David
Date Issued
November 7, 2023
Journal
Paleoceanography and Paleoclimatology
Publisher
American Geophysical Union (AGU)
Citation
Tiger, B. H., Burns, S., Dawson, R. R., Scroxton, N., Godfrey, L. R., Ranivoharimanana, L., et al. (2023). Zonal Indian Ocean variability drives millennial-scale precipitation changes in northern Madagascar. Paleoceanography and Paleoclimatology, 38, e2023PA004626.
Version
Final published version
Abstract
The low latitude Indian Ocean is warming faster than other tropical basins, and its interannual climate variability is projected to become more extreme under future emissions scenarios with substantial impacts on developing Indian Ocean rim countries. Therefore, it has become increasingly important to understand the drivers of regional precipitation in a changing climate. Here we present a new speleothem record from Anjohibe, a cave in northwest (NW) Madagascar well situated to record past changes in the Intertropical Convergence Zone (ITCZ). U‐Th ages date speleothem growth from 27 to 14 ka. δ18O, δ13C, and trace metal proxies reconstruct drier conditions during Heinrich Stadials 1 and 2, and wetter conditions during the Last Glacial Maximum and Bølling–Allerød. This is surprising considering hypotheses arguing for southward (northward) ITCZ shifts during North Atlantic cooling (warming) events, which would be expected to result in wetter (drier) conditions at Anjohibe in the Southern Hemisphere tropics. The reconstructed Indian Ocean zonal (west‐east) sea surface temperature (SST) gradient is in close agreement with hydroclimate proxies in NW Madagascar, with periods of increased precipitation correlating with relatively warmer conditions in the western Indian Ocean and cooler conditions in the eastern Indian Ocean. Such gradients could drive long‐term shifts in the strength of the Walker circulation with widespread effects on hydroclimate across East Africa. These results suggest that during abrupt millennial‐scale climate changes, it is not meridional ITCZ shifts, but the tropical Indian Ocean SST gradient and Walker circulation driving East African hydroclimate variability.
MIT Department
Joint Program in Oceanography/Applied Ocean Science and Engineering
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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DOI of Published Version
10.1029/2023pa004626
