Pacific Ocean inflow: Influence on catastrophic reduction of sea ice cover in the Arctic Ocean

TLDR

Recent Arctic ice loss mirrors the distribution of warm Pacific Summer Water in the southern Canada Basin, and rising PSW temperatures correlate with the late‑1990s onset of sea‑ice decline, yet PSW warming is not linked to upstream Bering Sea source water, implying another controlling mechanism. The study aims to test a feedback hypothesis that delayed early‑winter sea‑ice formation weakens internal ice stresses, enhancing wind‑ocean coupling. This mechanism posits that reduced ice stresses allow anticyclonic winds to more efficiently transfer heat into the upper ocean, raising PSW flux. The increased PSW flux triggered catastrophic sea‑ice loss, confirming the proposed feedback.

Abstract

The spatial pattern of recent ice reduction in the Arctic Ocean is similar to the distribution of warm Pacific Summer Water (PSW) that interflows the upper portion of halocline in the southern Canada Basin. Increases in PSW temperature in the basin are also well‐correlated with the onset of sea‐ice reduction that began in the late 1990s. However, increases in PSW temperature in the basin do not correlate with the temperature of upstream source water in the northeastern Bering Sea, suggesting that there is another mechanism which controls these concurrent changes in ice cover and upper ocean temperature. We propose a feedback mechanism whereby the delayed sea‐ice formation in early winter, which began in 1997/1998, reduced internal ice stresses and thus allowed a more efficient coupling of anticyclonic wind forcing to the upper ocean. This, in turn, increased the flux of warm PSW into the basin and caused the catastrophic changes.