Growth Increments of Coralline Red Alga Clathromorphum Compactum Capture Sea‐Ice Variability Links to Arctic and Atlantic Multidecadal Oscillations (1805–2015)

Abstract

Given sea ice's importance in global climate regulation, fully understanding the role of natural temperature and atmospheric patterns like the Arctic Oscillation (AO), North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation (AMO) in its variability is critical. While instrumental AMO and reliable AO records are available since the mid‐1800s and 1958, respectively, satellite sea‐ice concentration data sets start only in 1979, limiting the shared timespan to study their interplay. Growth increments of the coralline algae, Clathromorphum compactum, can provide sea‐ice proxy information for years prior to 1979. We present a seasonal 210‐year algal record from Lancaster Sound in the Canadian Arctic Archipelago capturing low frequency AMO/NAO variability and high frequency interannual AO/NAO prior to 2000. We suggest that sea‐ice variability here is strongly coupled to these large‐scale climate processes, and that sea‐ice cover was greater and the AO more negative in the early and late 19th century compared to the 20th.