Abstract Over the past five decades, the Ross Sea has freshened, but the mechanisms remain unclear. This study uses oxygen isotopes to trace freshwater transport from the Amundsen Sea to the Ross Sea. Results show that Winter Water (WW) in the Antarctic Slope Current (ASC) has lower δ18O values (<−0.7‰) due to glacial meltwater (GMW) inputs from the Amundsen Sea shelf. Modified Circumpolar Deep Water (mCDW) in the Ross Sea, formed by mixing upwelled Upper Circumpolar Deep Water and ASC WW, has intermediate salinity and δ18O values. High Salinity Shelf Water (HSSW) forms from mCDW during sea ice formation and is further modified by mixing with GMW, resulting in distinctly low δ18O of <−0.8‰. In 2020, HSSW δ18O averaged 0.25‰ lower than in 2000, suggesting freshwater from the Amundsen Sea and local ice shelf melting contribute to the Ross Sea’s freshening. This highlights the importance of understanding marginal sea interactions in climate change.
Observations from the Little Bunker
Last updated: November 30, 2025 04:25 AM
Atmospheric CO₂
426.8 ppm
+18.1
ppm/year
Atmospheric CH₄
1927.61 ppb
+2.73
ppb/year
Global Temperature
+1.48 °C
Peak: +1.73°C
World Population
8.1 billion
+67
million/year