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

• Main Authors: Lechleitner, F.A., Breitenbach, S.F.M., Rehfeld, K., Ridley, H.E., Asmerom, Y., Prufer, K.M., Marwan, N., Goswami, B., Kennett, D.J., Aquino, V.V., Polyak, V., Haug, G.H., Eglinton, T.I., Baldini, J.U.L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: London : Nature Publishing Group 2017
• Subjects: hydrologic seesaw; rainfall; ITCZ; 550; North Atlantic; North Atlantic oscillation
• Online Access: https://oa.tib.eu/renate/handle/123456789/5173; https://doi.org/10.34657/3802

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. publishedVersion