Multiscale Atlantic Forcing of ITCZ Shifts and Hydroclimatic Variability in Northeastern Brazil over the Last Millennium

Vásquez P I.L.; Sánchez P C.A.; Zeri M.; Ayuga J.G.R.; Pareja-Quispe D.; Karam H.A.; Calheiros A.J.P. · Earth Systems and Environment (2026) · DOI: 10.1007/s41748-026-01155-x

Resumen

This study investigates the non-stationary evolution of Atlantic multidecadal variability and its influence on hydroclimate in Northeastern Brazil (NEB) over the last millennium. By integrating high-resolution paleoclimate proxies (speleothems and marine sediments) with isotope-enabled climate simulations from the GISS-E2-R model, we move beyond confirming the well-established AMV-ITCZ link and instead document how the tropical Atlantic-South American climate system responded to a superposition of drivers across distinct climatic intervals. During the Medieval Climate Anomaly (950-1300 CE), variability was characterized by a persistent 64-year cycle associated with a positive phase of Atlantic Multidecadal Variability (AMV) and a northward displacement of the Intertropical Convergence Zone (ITCZ), intensifying aridity over NEB. The transition period (1301-1499 CE) was characterized by a more irregular 8-year cycle, likely reflecting enhanced climatic instability driven by interactions among ENSO dynamics, volcanic forcing, and internal Atlantic variability. During the Little Ice Age (1500-1849 CE), a 32-year cycle emerged, associated with a negative AMV phase, a southward ITCZ shift, and wetter conditions over NEB. Our findings demonstrate that NEB hydroclimate reflects a non-stationary superposition of internal variability (AMV, ENSO) and external forcings (volcanism, solar variability), rather than a single dominant driver. This multi-scale framework provides a long-term perspective for understanding present-day climate variability and improving future drought risk projections in the region. © The Author(s) 2026.

Instituciones: Universidad Nacional Mayor de San Marcos