The impact of recent high-latitude hydrographic perturbations on the tropical ocean interior is poorly constrained. Here, we reconstruct seawater barium ([Ba]_sw) records from bamboo coral growing over the last 160 years at intermediate depth (1409 – 1985 m) across the tropical North Atlantic. For this purpose, we establish a global calibration for bamboo coral Ba/Ca ratios and [Ba]_sw: Ba/Ca_coral = [Ba]_sw × (0.133 ± 0.003) – (0.05 ± 0.2). The coral records reveal a coherent cross-basin [Ba]_sw enrichment commencing in the ~1960s, synchronous with increased radiocarbon as reconstructed by the same corals. We interpret this systematic change in [Ba]_sw and radiocarbon as evidence for enhanced influence of deeper, Ba-enriched and relatively well-ventilated waters at the coral depths, potentially reflecting a shoaled North Atlantic Deep Water (NADW). More broadly, this low-latitude response is consistent with high-latitude hydrographic anomalies associated with North Atlantic freshening during the mid- to late-20^th century, and is also broadly consistent with proxy-based reconstruction of AMOC weakening over the same interval. These findings provide new observational constraints on the sensitivity of tropical intermediate waters to high-latitude perturbations.

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