Full Breakdown
North Atlantic Cold Blob Signals Slowing Conveyor
6/16/2026, 10:58:33 AM
The Cold Blob: A Cooling Anomaly
Scientists have identified a region of cooler sea surface temperatures south of Greenland and Iceland. Observations show cooling of up to 1 °C (1.8 °F) since the late 19th century, contrasting with overall ocean warming.
Research Team and Findings
A June 16 study in *Geophysical Research Letters* re-examined temperature and heat-flux records back to 1870, with data from 1993 onward. Led by Wei Liu and PhD candidate Kai-Yuan Li at UC Riverside and complemented by Stefan Rahmstorf of the Potsdam Institute, the analysis found reduced atmospheric heat loss and a decline in heat content within the upper 1,000 m, indicating a weakening of the Atlantic Meridional Overturning Circulation (AMOC).
Observed Changes and Projected Impacts
Surface cooling of about 1 °C extends deep into the water column, while heat-flux data show decreasing atmospheric heat loss since 1993. Independent assessments project at least a 20 % AMOC weakening by 2100, with a 30 % slowdown between 2009-2010 linked to a 128 mm sea-level rise north of New York City. Models associate a weakened AMOC with cooler air temperatures, altered storm tracks, faster sea-level rise along the U.S. East Coast, harsher European winters, shifted rainfall belts, heightened drought risk in southern Europe, and potential changes to marine ecosystems.
Official Assessments and Uncertainties
The study authors warn that a minimum 20 % AMOC weakening by the end of the century is likely and that a complete shutdown remains possible. The Intergovernmental Panel on Climate Change (IPCC) nonetheless concludes that an abrupt AMOC failure before 2100 is unlikely. Some climate simulations still project a possible mid-century collapse, while others place the threshold later, reflecting a wide spread in model outcomes and underscoring uncertainty about the timing and likelihood of a rapid transition.
Conflicting Evidence & Gaps
Discrepancies persist between model-based AMOC slowdown estimates and direct observations. The precise magnitude of future sea-level acceleration and regional climate shifts remains unresolved, highlighting the need for longer-term monitoring and integrated data sets.
Verbatim Quotes
- “The region to the south of Greenland is highly sensitive to AMOC change, where the surface cooling due to an AMOC slowdown may exceed background greenhouse gas warming,” — Wei Liu, Associate Professor, University of California, Riverside
- “One of the most striking features of modern climate change is a region south of Greenland that has cooled while most of the global ocean has warmed. This is called the North Atlantic Warming Hole or the North Atlantic Cold Blob,” — Kai-Yuan Li, PhD Candidate, UC Riverside
- “For thirty years of my career studying this, I considered the #AMOC tipping risk a high impact but low probability risk for the future of humanity,” — Stefan Rahmstorf, Potsdam Institute for Climate Impact Research
- “The observed cooling trend cannot be explained by surface heat flux changes,” — Authors of the 2025 AMOC slowdown study
Future Monitoring and Research
Continued oceanic observations, including salinity and temperature profiling, will track the cold blob’s evolution and refine AMOC projections. Researchers stress integrating measurements with climate models to improve early-warning capabilities for changes.
