The mysterious North Atlantic cold blob might be a warning sign
In short: While global sea temperatures have risen by about 1.8 degrees Fahrenheit since 1900, a specific patch of the Atlantic south of Greenland and Iceland is doing the opposite. This chilling anomaly, known as the 'cold blob,' could signal a fundamental shift in Earth's climate regulation.
The Atlantic Meridional Overturning Circulation (AMOC) acts as a global conveyor belt, transporting warm, salty water from the tropics toward the North Atlantic. As this water moves north, it cools and becomes denser, eventually sinking into the deep ocean. This process is vital for regulating global weather; it provides the heat that keeps the UK and Western Europe much milder than other regions at similar latitudes, such as Labrador or southern Alaska.
However, scientists are observing a 'cold blob'—a significant temperature anomaly south of Greenland and Iceland. While some researchers previously thought local winds might be stripping heat from the surface, recent studies suggest the cause is deeper. The cooling likely occurs because the AMOC is not delivering enough warm water to the region in the first place. This slowdown is potentially driven by freshwater from the melting Greenland ice sheet. Because freshwater is less dense than salty water, it floats on the surface, preventing the necessary sinking mechanism that drives the circulation.
The implications of a weakening AMOC are profound. A study published in May 2026 suggests that the AMOC could reach a tipping point by the middle of this century under high-emissions scenarios. Such a shift could lead to much colder winters in Europe—potentially even plunging Iceland into -50 degree Fahrenheit winters—and contribute to sea-level rise on the U.S. East Coast. Furthermore, the cold blob can influence the jet stream, creating 'omega blocks' that trap high pressure and contribute to intense heat domes and heatwaves in the UK.
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Sources
- Summary by Intellect · source: What is AMOC? And what is the North Atlantic ‘cold blob’? PML’s Dr de Mora breaks down the science
- Also: As the Ocean Warms, a 'Cold Blob' in the Atlantic Has Puzzled Scientists. It Might Be a Warning Sign About a Key Current System
- Also: Cold blob
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