Signal and noise in the Atlantic Meridional Overturning Circulation at 26°N

McCarthy, Gerard D. ORCID: https://orcid.org/0000-0002-2363-0561; Hug, Guillaume ORCID: https://orcid.org/0009-0009-7343-6562; Smeed, David ORCID: https://orcid.org/0000-0003-1740-1778; Morris, Kirsty J.; Moat, Ben ORCID: https://orcid.org/0000-0001-8676-7779. 2025 Signal and noise in the Atlantic Meridional Overturning Circulation at 26°N. Geophysical Research Letters, 52 (7). 10.1029/2025GL115055

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Official URL: https://doi.org/10.1029/2025GL115055

Abstract/Summary

The Atlantic meridional overturning circulation (AMOC) plays a crucial role in redistributing heat within the climate system. The RAPID mooring array has observed an AMOC weakening of 1.0 [0.4–1.6] Sv per decade from 2004 to 2023, consistent with climate model projections and not consistent with a collapse in the mid-21st century. Here, we analyze the AMOC change within a signal-to-noise framework. We find a strong signal in Lower North Atlantic Deep Water (LNADW) and thermocline transports. By removing the influence of Ekman transport on AMOC and LNADW estimates, we reduce noise by 30% and 22%, respectively. Moreover, we demonstrate that a simple model of LNADW yields a comparable signal-to-noise ratio to the full AMOC estimate. Ultimately, we conclude that current AMOC trends are unlikely to reach “unfamiliar” (signal-to-noise ratio > 2) or “unknown” (signal-to-noise ratio > 3) thresholds until the 2040s and 2060s, respectively.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1029/2025GL115055
ISSN:	0094-8276
Additional Keywords:	meridional overturning circulation, rapid climate change, ocean observing systems, detection of climate change, deep circulation, ocean variability
Date made live:	01 Apr 2025 13:52 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/539195

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1029/2025GL115055

ISSN:

0094-8276

Additional Keywords:

meridional overturning circulation, rapid climate change, ocean observing systems, detection of climate change, deep circulation, ocean variability

Date made live:

01 Apr 2025 13:52 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/539195