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Abstract By synthesizing recent studies employing a wide range of approaches (modern observations, paleo reconstructions, and climate model simulations), this paper provides a comprehensive review of the linkage between multidecadal Atlantic Meridional Overturning Circulation (AMOC) variability and Atlantic Multidecadal Variability (AMV) and associated climate impacts. There is strong observational and modeling evidence that multidecadal AMOC variability is a crucial driver of the observed AMV and associated climate impacts and an important source of enhanced decadal predictability and prediction skill. The AMOC‐AMV linkage is consistent with observed key elements of AMV. Furthermore, this synthesis also points to a leading role of the AMOC in a range of AMV‐related climate phenomena having enormous societal and economic implications, for example, Intertropical Convergence Zone shifts; Sahel and Indian monsoons; Atlantic hurricanes; El Niño–Southern Oscillation; Pacific Decadal Variability; North Atlantic Oscillation; climate over Europe, North America, and Asia; Arctic sea ice and surface air temperature; and hemispheric‐scale surface temperature. Paleoclimate evidence indicates that a similar linkage between multidecadal AMOC variability and AMV and many associated climate impacts may also have existed in the preindustrial era, that AMV has enhanced multidecadal power significantly above a red noise background, and that AMV is not primarily driven by external forcing. The role of the AMOC in AMV and associated climate impacts has been underestimated in most state‐of‐the‐art climate models, posing significant challenges but also great opportunities for substantial future improvements in understanding and predicting AMV and associated climate impacts.
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An Externally Forced Decadal Rainfall Seesaw Pattern Over the Sahel and Southeast Amazon
Abstract By analyzing observations and model simulations, here we show that there exists a significant anticorrelation on interannual to multidecadal time scales between the Sahel and southeast Amazon rainfall during July‐August‐September. This rainfall seesaw, which is strongest on decadal to multidecadal scales, is due to an anomalous meridional gradient of sea surface temperatures across the tropical Atlantic that pushes the Intertropical Convergence Zone and its associated rain belt toward the anomalously warm hemisphere. Large ensemble model simulations suggest that the seesaw pattern is likely caused by decadal changes in anthropogenic and volcanic aerosols, rather than internal climate variability. Our results suggest that the recent decadal to multidecadal climate variations in and around the North Atlantic basin are largely externally forced and that projected large North Atlantic warming could lead to a wetter Sahel but drier Amazon in the future.
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- Award ID(s):
- 1743738
- PAR ID:
- 10457215
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 46
- Issue:
- 2
- ISSN:
- 0094-8276
- Page Range / eLocation ID:
- p. 923-932
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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