Bivalve Shells—Unique High-Resolution Archives of the Environmental Past - Towards an Interdisciplinary Approach in Earth System Science - page 159

Bivalve Shells — Unique High-Resolution
Archives of the Environmental Past

Lars Beierlein, Gernot Nehrke, Tamara Tro mova and Thomas Brey

Abstract Understanding the climate of the past is essential for anticipating future
climate change. Palaeoclimatic archives are the key to the past, but few marine
archives (including tropical corals) combine long recording times (decades to
centuries) with high temporal resolution (decadal to intra-annual). In temperate and
polar regions carbonate shells can perform the equivalent function as a proxy
archive as corals do in the tropics. The bivalve Arctica islandica is a particularly
unique bio-archive owing to its wide distribution throughout the North Atlantic and
its extreme longevity (up to 500 years). This paper exempli

es how information at
intra-annual and decadal scales is derived from A. islandica shells and combined
into a detailed picture of past conditions. Oxygen isotope analysis (

18 O) provides
information on the intra-annual temperature cycle while frequency analysis of shell
growth records identi

δ

es decadal variability such as a distinct 5-year signal, which
might be linked to the North Atlantic Oscillation.

Keywords Sclerochronology Arctica islandica Frequency analysis Raman

microscopy Stable oxygen isotopes Palaeoceanography Intra-annual Decadal

1 Introduction

Current predictions of future climate change (e.g., IPCC 2013 ) are based on global
circulation models (GCM) to a large extent. Such models incorporate observational
and instrumental data of the oceans, continents and atmosphere. Instrumental data
are available for

the last two centuries at best, but we need climate and