Franziska A. Lechleitner a , 1 , 2 , Sebastian F. M. Breitenbach 3 , Kira Rehfeld 4 , Harriet E. Ridley 2 , Yemane Asmerom 5 , Keith M. Prufer 6 , Norbert Marwan 7 , Bedartha Goswami 7 , 8 , Douglas J. Kennett 9 , Valorie V. Aquino 6 , Victor Polyak 5 , Gerald H. Haug 1 , 10 , Timothy I. Eglinton 1 , James U. L. Baldini 2
05 April 2017
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.