Ecosystem relevant variations and oceanographic trends from present day to 2070

We investigate the present state (1980-2019) of the ocean using both observations and output from high- resolution ocean models. To investigate future changes, we use an ensemble of forecast model experiments covering the period 2014-2070. These datasets are used with three objectives in mind: (i) characterise present and future changes in the Atlantic Meridional Overturning Circulation (AMOC) strength at various latitudes throughout the Atlantic Ocean; (ii) analyse present and future changes in the key water masses at the 12 iAtlantic case study regions; (iii) investigate extreme events in the form of MHWs.

The report is structured as follows: First, we provide an overview of the AMOC and how it connects the entire Atlantic Ocean system, before describing the main dynamic regimes and water masses for each of the 12 iAtlantic case study regions. Next, we introduce the datasets used and our methodology. In the results section, we first present the variability of the AMOC between 1980 and 2070 focussing on latitudes relevant to the iAtlantic regions. We then show time series of temperature and salinity between 1980- 2070 for the main water masses in each region and give a brief discussion of the results with respect to changes in the circulation. Next, we use the MHW algorithm to examine extreme events for the period 1980-2019. Finally, we provide a summary of the key results.