Enhanced, Climate‐Driven Sedimentation on Salt Marshes

Abstract

Abstract With Arctic amplification (enhanced polar warming) possibly increasing periods of intense winter freezing and global warming producing more powerful extratropical storms, winter sedimentation on northern salt marshes may likely increase in the future. Here, we show that a large ice‐rafting event in northern Massachusetts delivered the equivalent of 15 years of mineral deposition to the marsh surface in a single storm. During an intense extratropical cyclone in January 2018, sediment‐laden ice was rafted onto the Great Marsh, Massachusetts, by an ~1‐m storm surge coinciding with high astronomical tides. The muddy sand content combined with abundant shells indicates that the sediment originated from proximal bays and tidal flats. Sediment layers delivered by individual ice rafts averaged 3.19 cm in thickness, 12 times the combined organic and inorganic yearly vertical accretion rate on high marshes. This previously underappreciated vector for sediment deposition is likely to help marsh resiliency to sea‐level rise.