Journal Article

Concurrent Decadal Trend Transitions of Sea Ice Concentration and Sea Surface pCOsub.2 in the Beaufort Sea

Jin, Meibing, Chi, Shangbin

2026

Overview

What are the main findings? * A decadal trend transition in sea surface pCO[sub.2] in the Beaufort Sea was found around 2010–2012 both by observation and via a numerical model. * The sea surface pCO[sub.2] trend transition was driven by a concurrent trend transition in sea ice cover through changing the seasonal duration of open-water. A decadal trend transition in sea surface pCO[sub.2] in the Beaufort Sea was found around 2010–2012 both by observation and via a numerical model. The sea surface pCO[sub.2] trend transition was driven by a concurrent trend transition in sea ice cover through changing the seasonal duration of open-water. What are the implications of the main findings? * This finding improves our understanding of the decadal-scale response of the Arctic Ocean carbon cycle to climate changes. * This finding advances our understanding of the influence of seasonal sea ice variabilities on decadal trends in the carbon cycle. This finding improves our understanding of the decadal-scale response of the Arctic Ocean carbon cycle to climate changes. This finding advances our understanding of the influence of seasonal sea ice variabilities on decadal trends in the carbon cycle. Interannual climate changes and increasing atmospheric CO[sub.2] (AtmCO[sub.2]) have significantly altered sea surface partial pressure of CO[sub.2] (pCO[sub.2]) in the Beaufort Sea (BS). Yet, their decadal variability and underlying mechanisms remain inadequately understood. Using observational data and the Regional Arctic System Model (RASM), a decreasing trend transition of the BS summer surface pCO[sub.2] was identified at around 2010–2012. Sensitivity cases reveal that the decadal trend transition in surface pCO[sub.2] (early: 4.12 ± 0.80 μatm/yr, p < 0.05 and late: 1.23 ± 2.22 μatm/yr, p > 0.05) is driven by interannual climate changes. While the long-term increase in AtmCO[sub.2] does not directly drive surface pCO[sub.2] trend transition, it reduces its magnitude. The sensitivity experiment with no interannual AtmCO[sub.2] changes from 1990 reveals that the statistically significant contributor of the decadal trend transition in surface pCO[sub.2] is the concurrent transition in sea ice concentration (SIC, early: −0.0120 ± 0.0037/yr, p < 0.05 and late: 0.0101 ± 0.0063/yr, p > 0.05). The decadal trend transitions in the subsurface and deep layer pCO[sub.2] are negligible compared to that in the sea surface pCO[sub.2] due to the insignificant influence of interannual climate changes on subsurface and deep layer pCO[sub.2]. The surface pCO[sub.2] decadal trend transition is significantly correlated with a trend transition of CO[sub.2] sink. On seasonal timescales, the effects of SIC on the decadal trend transition of pCO[sub.2] occur primarily within the duration of open-water (DOW), and align with the decadal trend transitions in the open-water start day, end day, and DOW. The magnitude of sea surface pCO[sub.2] trend transition increases as the magnitude of the DOW trend transition increases.

• Publisher: MDPI AG
• Subject: Atmospheric carbon dioxide / Carbon cycle (Biogeochemistry) / Sea ice