Seasonality in the North Sea during the Allerød and Late Medieval Climate Optimum using bivalve sclerochronology

Abstract

Seasonal temperature patterns may have changed through time in response to current global warming. However, the temporal resolution of available proxy records is not sufficient to quantify paleotemperature seasonality prior to anthropogenic forcing of the climate. In the present study, we reconstructed seasonal and inter-annual temperature patterns of the North Sea during the last 140 years, the Allerød Interglacial and the Late Medieval Climate Optimum using sclerochronological and d 18 O aragonite data from bivalve shells, Arctica islandica. On average, the climate during 1278-1353 AD was ca. 1.1°C colder and seasonality was ca. 60% less than today. During the Allerød, long-term temperatures remained about 3.2°C below present values, and absolute summer and winter anomalies were ca. -4 and -2.7°C, respectively. However, seasonality was statistically indistinguishable from today. Long-term average temperatures compare well with existing data for the Late Medieval and Allerød, but detailed information on seasonality during the studied time intervals has never been presented before. Our data also demonstrated that annual instrumental and d 18 O aragonite -derived temperatures did not always match. This difference is explained by (1) NAOdriven salinity changes, which influence the temperature estimation from d 18 O aragonite and (2) food-driven changes in growth rates; portions of the shell that formed more rapidly are overrepresented in carbonate samples. Our study indicated that individual bivalve shells can open discrete, nearcentury long, ultra-high-resolution windows into the climate past. Such information can be vital for testing and verifying numerical climate models.

Seasonality fluctuations recorded in fossil bivalves during the early Pleistocene: Implications for climate change

“…The stable isotope composition of bivalve shell carbonate has been proven to be a very powerful tool for paleoclimatic and paleoenvironmental reconstructions (e.g., Schöne and Fiebig, 2009;Ivany and Runnegar, 2010;Royer et al, 2013;Beard et al, 2015). However, diagenetic processes may alter fossil bivalve shell isotope composition; for this reason it is important to check if the shell carbonate is pristine (i.e., unaltered from the time of growth).…”

Ecological information and water mass properties in the Mediterranean recorded by stable isotope ratios inPinna nobilisshells

“…The occurrence of clear growth increments in the shell and the longevity of P. nobilis potentially allows for the construction of master chronologies that extend beyond the lifetime of an individual animal, such as the master chronologies derived from A. islandica shells [ Scourse et al , 2006; Schöne and Fiebig , 2009; Butler et al , 2010]. Furthermore, the shell of P. nobilis may serve as a valuable recorder of environmental variables under a wide range of conditions and over relatively long time intervals.…”

Short-term fluctuations in vegetation and phytoplankton during the Middle Eocene greenhouse climate: a 640-kyr record from the Messel oil shale (Germany)

“…First, we applied the Morlet wavelets (Morlet 1983; Torrence and Compo 1998), a continuous wavelet transform, proven and tested in climate time series analysis (Lau and Weng 1995;Dunca et al 2009;Schöne and Fiebig 2009;Wanamaker et al 2009). The transform was based on the method described in Torrence and Compo (1998) by means of Wavelet software provided by these authors.…”