While working at the Bermuda Atlantic Time-series study (BATS) and Hydrostation-S projects at the Bermuda Institute of Ocean Sciences, I studied long-term changes in the water mass structure in the BATS region, with a specific focus on Subtropical Mode Water. This water mass, dubbed ''eighteen degree water`` due to its consistent and characteristic 18°C temperature, is a significant sink for carbon dioxide and acts as an important nutrient source for organisms in the surface waters. In the 2010's, we documented a dramatic loss of STMW linked to increased surface warming in the North Atlantic.
