New paper finds NE Atlantic relative sea levels have been stable to decreasing over past 2000 years

A paper published today in Quaternary Science Reviews finds relative sea levels in the eastern North Atlantic have been stable to declining over the last 2000 years. The authors attribute this to land uplift since the last ice age [post-glacial rebound]. 

The authors compare their 2 sites on the NE Atlantic to 2 others in the NW Atlantic: New Jersey & North Carolina, which show relative sea level rise due to subsidence.

The paper demonstrates that relative sea level rise is predominantly a regional phenomenon due to land subsidence or uplift. Relative sea levels in areas little-affected by land height changes are changing very slowly over time - only about 3 to 4 inches per century - which is the only true sea level contribution from warming. 

Middle 2 graphs show the two sites in this study, each showing RSL [Relative Sea Level] has been stable to declining over the past 2000 years

The authors compare their 2 sites on the NE Atlantic to 2 others in the NW Atlantic: New Jersey & North Carolina, which show RSL rise due to subsidence [land sinking]

Salt-marsh reconstructions of relative sea-level change in the North Atlantic during the last 2000 years

• Natasha L.M. Barlow^a, , , 
• Antony J. Long^a, 
• Margot H. Saher^b, 1, 
• W. Roland Gehrels^b, 
• Mark H. Garnett^c, 
• Rob G. Scaife

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First 2000 year continuous salt marsh record of RSL from eastern North Atlantic.

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RSL [Relative Sea Level Rise] in north west Scotland has been stable (±0.4 m) during the last two millennia.

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Regional sea-level tendency has been negative throughout most of the record lengths.

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20th century acceleration appears more muted than recorded along western North Atlantic.

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Replicated diatom samples show noise in proxy datasets but consistency of results.

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Abstract

Sea-level changes record changes in the mass balance of ice sheets and mountain glaciers, as well as dynamic ocean–atmosphere processes. Unravelling the contribution of each of these mechanisms on Late Holocene timescales ideally requires observations from a number of sites on several coasts within one or more oceans. We present the first 2000 year-long continuous salt marsh-based reconstructions of relative sea-level (RSL) change from the eastern North Atlantic and uniquely from a slowly uplifting coastline. We develop three RSL histories from two sites in north west Scotland to test for regional changes in sea-level tendency (a positive tendency indicating an increase in the proximity of marine conditions and a negative tendency the reverse), whilst at the same time highlighting methodological issues, including the problems of dataset noise when applying transfer functions to fossil salt-marsh sequences. The records show that RSL has been stable (±0.4 m) during the last two millennia, and that the regional sea-level tendency has been negative throughout most of the record lengths. A recent switch in the biostratigraphy of all three records, indicating a regional positive tendency, means we cannot reject the hypothesis of a 20th century sea-level acceleration occurring in north west Scotland that must have exceeded the rate of background RSL fall (−0.4 mm yr⁻¹), but this signal appears muted and later than recorded from the western North Atlantic.