Quantifying past AMOC changes (WP1)

Objective: Generate comprehensive records of AMOC transports across the whole Atlantic, to assess the timescales of transport variability and the degree to which the AMOC behaves as a conveyor belt.


  • Generate consistent records of heat, freshwater and overturning transports from 35°S-80°N (1993-2022), and through Arctic gateways (2004-2020), and reconstructions of deep boundary currents from sediment cores (focussing on changes since 1850);
  • Evaluate the fidelity of AMOC transport variability in coupled models (low and high resolution);
  • Assess the meridional coherence of the AMOC, regional drivers of change in climate indicators, and their impacts on European and global climate.

Since the early 2000s AMOC observing systems have been deployed in the Atlantic. This was the beginning of a new era for our understanding of the AMOC: for the first time we had continuous observations of its strength and variability. In parallel, advances in modelling the ocean allowed us to simulate the ocean with ever-increasing levels of realism.

Despite these advances we have not been able to provide a consistent view of the AMOC for the whole Atlantic. Differences in the observing systems deployed at different latitudes make it difficult to compare AMOC observations from different locations. At the same time, limitations in the level of detail that models can simulate, as well as simplifications in ocean physics which are required in order to make simulations computationally affordable, means that there is only limited agreement between the observed and simulated AMOC.

In EPOC we will produce a novel, consistent observation-based estimate for the heat and freshwater transports from the Arctic and Nordic Seas to the southern limit of the Atlantic at 34.5S. A new technique will be used to estimate the exchanges of heat and freshwater between the Arctic and Atlantic oceans, and the latest generation of coupled climate models will be used to assess how the AMOC variability at any given latitude relates to the variability at other latitudes (i.e. the “coherence” of the AMOC).