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Positive phases of the North Atlantic Oscillation (NAO), the large-scale pressure seesaw over the North Atlantic, coincided with wetter but colder conditions in southwestern Greenland. A study published on 21 August 2026 in Nature Communications reconstructs this link across the Holocene, the last roughly 12,000 years, using a sediment core from a fjord. The result describes how precipitation and glaciers behaved in the past. It does not predict how the ice sheet will respond to today’s warming.
How researchers read the past from fjord sediment
The sediment core came from Narsaq Sound, a fjord in southwestern Greenland. According to the study abstract, the record covers the entire Holocene. After local glaciers disappeared in the early Holocene, the sediments can be used to evaluate millennial- to decadal-scale changes in local precipitation.
The proxy: niobium
The core’s key signal is niobium (Nb), measured with X-ray fluorescence (XRF), a non-destructive way to determine which elements a sample contains. The nearby bedrock is unusually rich in niobium, while seawater generally holds very little of it. Glaciers and rivers can carry Nb-bearing sediment from the land into the fjord, so changes in the amount of niobium reaching the core can indicate changes in how much sediment was delivered, and that delivery depends on river discharge and glacial meltwater, which in turn depend on precipitation.
This makes niobium an indirect, site-specific proxy. It does not measure ancient rain or snowfall directly, and it does not record individual storms. Its value lies in the chain it implies: more precipitation means more sediment transport, and more sediment transport means a stronger niobium signal in the core.
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The comparison: NAO reconstructions and climate models
The sediment record was compared with independent NAO reconstructions and with climate-model simulations. The core result is therefore a relationship supported by that combined evidence. It is not a standalone measurement of atmospheric circulation.
What the record shows
The authors report that positive NAO phases correspond to wetter but colder regional conditions in southwestern Greenland. They conclude that this persistent, NAO-driven variability in hydroclimate, the combined behaviour of precipitation and temperature, likely influenced glacier behaviour and mass balance during parts of the late Holocene. Mass balance is the net result of snow and ice gained through accumulation minus what is lost through melting and calving.
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The authors also treat the NAO as one influence among several. Other factors, including sea-surface-temperature variability, may affect both the sediment record and regional hydroclimate. The paper notes that continuous, high-resolution sea-surface-temperature reconstructions for coastal southern Greenland spanning the Holocene are not yet available, which limits how fully those other factors can be separated from the NAO signal.
MARUM, the German research centre whose explainer accompanied the study, summarised the finding in the lead author’s words. Dr. Johan Faust said: “We can trace the influence of the North Atlantic Oscillation on southern Greenland’s hydroclimate over thousands of years.”
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What the result does not say about the future
The paper discusses projections that rising CO₂ may favour a more positive and less variable NAO state. The authors say that regional surface-mass-balance calculations under positive NAO conditions are consistent with the patterns inferred from the late-Holocene record. That consistency is a reason for further work, not a forecast.
The authors explicitly call for future regional climate and ice-sheet model analyses. Those studies would need to determine whether extra precipitation could offset increased melting, or even promote local glacier growth, or whether atmospheric warming remains the dominant control. Until those models are run, the study cannot say which effect wins. Readers should not take it as evidence that the Greenland Ice Sheet will grow.
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Past relationship versus future scenario
The table separates what the study can support from what it leaves open.
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Repair Windows errors before they cause bigger problemsFix Now →Scan for outdated or missing drivers - takes under a minuteDriver Scan →| Question | What the study supports | What it does not establish |
|---|---|---|
| Did NAO phases affect southwestern Greenland’s climate? | Yes, positive phases coincided with wetter, colder conditions, inferred from a sediment proxy compared with NAO reconstructions and model simulations. | A direct measurement of past rainfall or snowfall at a fixed rate or size. |
| Did this affect glaciers? | The authors conclude that NAO-driven hydroclimate variability likely influenced glacier behaviour and mass balance during parts of the late Holocene. | A quantified glacier-volume change or a specific ice-loss figure. |
| Will future precipitation offset warming? | Nothing conclusive. Calculations under positive NAO conditions are consistent with the past pattern. | Whether more snow would offset increased melting. Regional climate and ice-sheet modelling is still needed. |
Study details
- Paper: Johan C. Faust and coauthors, “Persistent influence of the North Atlantic Oscillation on Late Holocene hydroclimate in southwestern Greenland,” Nature Communications 17, 8817 (2026), published 21 August 2026. DOI: 10.1038/s41467-026-77084-0.
- Explainer: A MARUM-supplied article carried by Phys.org on 8 October 2026, which describes the method in accessible terms and includes the lead-author quotation.
- Record length: The Holocene, roughly the past 12,000 years, as described in the study abstract.
- Effect size: The paper’s central message is a proxy-based relationship rather than a headline percentage or count, so no single numerical effect is reported in the sources used here.
In short, this is a well-supported account of how a large-scale Atlantic pattern shaped southern Greenland’s precipitation and glacier history over thousands of years. It is not yet a forecast of how that same pattern will shape the ice sheet in a warmer world.
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