Tropical rainfall over the last two millennia: evidence for a low-latitude hydrologic seesaw

The presence of a low- to mid-latitude interhemispheric hydrologic seesaw is apparent over orbital and glacial-interglacial timescales, but its existence over the most recent past remains unclear. Here we investigate, based on climate proxy reconstructions from both hemispheres, the inter-hemispheri...

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Bibliographic Details
Published in:Scientific Reports
Main Authors: Lechleitner, F., Breitenbach, S., Rehfeld, K., Ridley, H., Asmerom, Y., Prufer, K., Marwan, N., Goswami, B., Kennett, D., Aquino, V., Polyak, V., Haug, G., Eglinton, T., Baldini, J.
Format: Article in Journal/Newspaper
Language:English
Published: 2017
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Online Access:http://hdl.handle.net/11858/00-001M-0000-002D-976E-4
Description
Summary:The presence of a low- to mid-latitude interhemispheric hydrologic seesaw is apparent over orbital and glacial-interglacial timescales, but its existence over the most recent past remains unclear. Here we investigate, based on climate proxy reconstructions from both hemispheres, the inter-hemispherical phasing of the Intertropical Convergence Zone (ITCZ) and the low- to mid-latitude teleconnections in the Northern Hemisphere over the past 2000 years. A clear feature is a persistent southward shift of the ITCZ during the Little Ice Age until the beginning of the 19th Century. Strong covariation between our new composite ITCZ-stack and North Atlantic Oscillation (NAO) records reveals a tight coupling between these two synoptic weather and climate phenomena over decadal-to-centennial timescales. This relationship becomes most apparent when comparing two precisely dated, high-resolution paleorainfall records from Belize and Scotland, indicating that the low- to mid-latitude teleconnection was also active over annual-decadal timescales. It is likely a combination of external forcing, i.e., solar and volcanic, and internal feedbacks, that drives the synchronous ITCZ and NAO shifts via energy flux perturbations in the tropics.