ARAMATE scientific goals

 

aramate fig 2
An example of the alignment of multiple ecosystem variables, in this case for the eastern north Pacific (from Black et al. 2014). Data shown are (top to bottom) the winter copepod index, auklet laying date, murre laying date, murre fledgling success, a splitnose rockfish otolith chronology, and the mean of 16 blue oak tree-ring chronologies. PC1bio is the leading principal component for all marine biological time series except copepods and CCWI is the California Current Winter Index which is constructed from three physical variables.

Recent work in the NE Pacific conducted by Bryan Black and coauthors (Black et al. 2014, Science) used high resolution timeseries of ecosystem variables to investigate the mechanisms of variability in coastal upwelling zones and to reconstruct such variability over the past six centuries.

The unique feature of their research is the combination of multiple proxy indicators of ecosystem and environmental variability to give insight into the dynamical mechanisms associated with the reconstruction target. Thus the interpretation of their tree-ring based reconstruction is validated by a mechanistic explanation supported by well-defined and (to varying extents) independent responses of ecosystem and climate variables in different marine and terrestrial ecosystems.

The North Atlantic Ocean is the site of several processes of importance in global ocean circulation and global climate including the Atlantic Meridional Overturning Circulation (AMOC) and the associated delivery of relatively warm water to the Arctic Ocean where it plays a part in the annual cycle of sea ice formation and melt.

Observed changes in the North Atlantic over the course of the 20th century – so-called "regime shifts"– have been reflected in marine ecosystems, with significant and coherent changes in the regional distribution of fish stocks and marine primary production (Drinkwater 2006).

To a first approximation, these changes are associated with large scale oscillations in basin wide temperatures which are averaged, detrended and indexed as the Atlantic Multidecadal Oscillation (AMO; eg Enfield 2001), but the periodicity of the AMO, its mechanisms, its relationship with the AMOC and its relationship with changes in the atmosphere remain uncertain (Drinkwater et al. 2014).

The key scientific question being addressed here is the analysis and definition of the dynamical mechanisms that result in ecosystem and climate variability in the North Atlantic Ocean. We will address this key question using natural high-resolution proxy archives, historical documentary records and (where available) instrumental records.

We propose here to identify and evaluate high resolution timeseries of ecosystems variables, including records of fisheries, changes in seabird populations and phytoplankton, that can be combined with high-resolution proxy archives and other documentary records to provide insights into climate and ecosystem variability in the North Atlantic region during the past two thousand years.