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Is the Atlantic heat conveyor slowing?

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What the Atlantic conveyor actually does

Warm surface water flows north, releases its heat to the air over the North Atlantic, becomes cold and salty enough to sink, and returns south at depth. It is one limb of a global loop that touches every ocean basin.

World map showing the global thermohaline circulation as a loop of red warm-surface currents and blue cold-deep currents. The map labels three regions where surface water sinks to depth: the subpolar North Atlantic south of Greenland, the Norwegian and Labrador Seas, and the Southern Ocean around Antarctica.
The global conveyor. Red ribbons are warm surface currents; blue ribbons are cold deep currents. The labelled “deep water formation” sites — including the subpolar North Atlantic south of Greenland — are where the conveyor sinks.
Three-dimensional view of the North Atlantic showing named currents that make up the conveyor: the North Atlantic Current and Norwegian Atlantic Current carrying warm surface water north (red and orange arrows), the East Greenland Current and overflows through the Denmark Strait carrying cold deep water south (blue and yellow arrows), and the Labrador, Irminger and Iceland basins labelled as the basins where sinking happens.
Zoomed into the North Atlantic. The same loop, up close. Warm water (red) reaches the seas around Iceland and Norway, cools, sinks, and returns south as the cold East Greenland Current and the overflows through the Denmark Strait (yellow). When the overturning weakens, less heat reaches the surface here — which is exactly the pattern in the “cold blob” map below.

Left: “Thermohaline Circulation” diagram via Wikimedia Commons. Right: ocean-circulation diagram of the North Atlantic and Nordic Seas via Wikimedia Commons.

Rest of the world is warming. This patch is different.

Sea-surface temperature trend · not a direct flow measurement

Where the ocean has warmed since the late 19th century — and the one spot it hasn’t

Robinson-projection world map of global temperature anomalies for 2015 compared to a 1951-1980 baseline. The entire globe is warmer than baseline (orange to deep red) with one striking exception: a deep-blue patch in the subpolar North Atlantic south of Greenland, known as the cold blob, and a smaller cool ring around Antarctica.
The whole world is warmer. One spot isn’t. The blue lobe south of Greenland is the “cold blob” — the visual signature climate scientists most often associate with a slowing Atlantic overturning conveyor. The colour bar at the top-left of the map shows the anomaly scale in degrees Fahrenheit (−3.6°F to +3.6°F vs the 1951–1980 average).

Image: NASA Scientific Visualization Studio (2015 record-warm global temperatures), via Wikimedia Commons. Public domain.
Conveyor strength today
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How fast it's slowing
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Sv per decade (RAPID annual means)
Cold-blob temperature
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Second-opinion reading
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How much water the conveyor moved, year by year

Each point is one year's average. Higher = more water moving north (a stronger conveyor). The dashed line is the early-2000s average. Gold markers flag landmark research papers.

    Also in the literature

      How weak could the Atlantic conveyor get this century?

      Schematic strength of Atlantic overturning as a share of today's flow — not a live forecast dial.

      Today's strength is from the RAPID mooring array at 26°N. The Intergovernmental Panel on Climate Change Sixth Assessment Report likely-range is a band, not a point — drawn here at its midpoint for visual reference. Baker et al. 2026 (Science Advances) is the latest observation-constrained projection and sits below the multi-model mean.

      What Atlantic overturning weakening means near you

      Pick a country to see how a weaker Atlantic conveyor would reach it — or share your approximate location and we'll pick for you.

      Your location is only checked when you press the button. The lookup uses ipapi.co and reads only your country and region.

      Choose a country above to see the impact profile.

      What drives this

      • Ocean heat →Warming changes density contrasts and the heat carried north.
      • Polar ice →Freshwater from ice melt can cap dense-water formation in the North Atlantic.

      What this drives

      How we know this

      • Sources: Annual transport from the RAPID-MOCHA-WBTS observing array (published via the British Oceanographic Data Centre), the Atlantic Multidecadal Variability sea-surface-temperature index from the United States National Oceanic and Atmospheric Administration Physical Sciences Laboratory, the published Overturning in the Subpolar North Atlantic Program mean, and recent-paper metadata from OpenAlex.
      • Update cadence: The Atlantic Multidecadal Variability index and the recent-papers list refresh on our build schedule; the mooring-array values update only when a new release is published (often years behind the calendar date).
      • Time coverage: Direct overturning at 26°N since 2004 only; the sea-surface-temperature fingerprint runs back to 1856; landmark papers are annotated on the chart.
      • Methods: The hero percent uses the 2004–2008 RAPID mean as a baseline; the cold-blob map is a schematic pattern derived from the Atlantic Multidecadal Variability index, not raw sea-surface-temperature pixels.
      • Uncertainty: Twenty years of RAPID measurements cannot prove a collapse; the Intergovernmental Panel on Climate Change Sixth Assessment Report treats a shutdown this century as unlikely but not impossible at high emissions. Papers disagree on tipping risk. The sea-surface-temperature fingerprint method is becoming less reliable in a warming world (Mackay et al. 2024).
      • Limitations: The Atlantic overturning conveyor is related to, but not the same as, the Gulf Stream. The "near you" panel uses coarse internet-protocol geolocation (ipapi.co) only when the reader presses the button. Pre-2004 trends require paleo-climate proxies with wider error bars.
      • Primary data: RAPID-MOCHA-WBTS observing array · United States National Oceanic and Atmospheric Administration — Atlantic Multidecadal Variability index · Intergovernmental Panel on Climate Change Sixth Assessment Report — Working Group I, Chapter 9 · How this page is built