Warming Trend in Antarctic Bottom Water in the Vema Channel in the South Atlantic

The excess heat absorbed from the atmosphere has increased the temperature in the upper layers of the ocean (<2,000 m). In the abyss, infrequently repeated ship sections, deep Argo float measurements, and sparse moored observations have found signs of warming in the Southwest Atlantic, possibly linked to changes in the Weddell Sea. We present a new moored temperature time series sampled near the bottom in the Vema Channel, from February 2019 to August 2020. Together with historical data, the combined record confirms the warming of the abyssal waters, with an increase of 0.059 degrees C in potential temperature between January 1991 and August 2020, embedded within intense high-frequency variability. Moreover, the data suggest the possibility of an accelerated warming, with a change in the temperature trend from 0.0016 degrees C yr(-1), between the early 1990s and 2005, to 0.0026 degrees C yr(-1) afterwards.

Automated summary

Research has found that excess heat absorbed from the atmosphere has led to an increase in temperature in the upper layers of the ocean, with signs of warming also appearing in the abyss. Analysis of a new moored temperature time series, along with historical data, confirms the warming of abyssal waters and suggests a possible trend of accelerated warming.