A sea change in our view of overturning in the subpolar North Atlantic

The Atlantic meridional overturning circulation (AMOC) has a strong influence on climate, so it is important to understand how global warming may affect it. Lozier et al. report initial results from the Overturning in the Subpolar North Atlantic Program (OSNAP) (see the Perspective by Rhein). OSNAP has been measuring the flux of water transported by overturning in the high latitudes in the North Atlantic. The measurements reveal the strong variability of transport in the region and show that deep water formation in the Labrador Sea may not, as previously believed, be the major determinant of AMOC variability.

By M. S. Lozier, et al.

Feb 1st, 2019

Taking a close look at ocean circulation

The large-scale Atlantic Ocean circulation moves warm, saline near-surface water from the tropics to far northern latitudes, where it cools, sinks, and returns southward at depth. The fundamental role of this Atlantic Meridional Overturning Circulation (AMOC) for the past, present, and future climate is regularly assessed in the Intergovernmental Panel on Climate Change (IPCC) reports, including the most recent special report on global warming of 1.5°C (1). However, observations of the AMOC are sparse, and scientific knowledge is mainly based on model simulations. On page 516 of this issue, Lozier et al. (2) estimate the strength of the AMOC from the subpolar North Atlantic based on 21 months of continuous observations from the OSNAP (Overturning in the Subpolar North Atlantic Program).

Monika Rhein

Feb 1st, 2019