Climate of the LAst Millennium (CLAM): An Integrated Data-Model Approach to Reconstruct and Interpret Annual Variability in North Atlantic Circulation
The ocean circulation of the North Atlantic is variable and pivotal in controlling regional and global climate. This variability occurs both naturally, and it is anticipated, in response to anthropogenic activity. Internal and forced natural variability in this system has so far largely been characterised in terrestrial archives and models rather than in the real ocean. It is critical that we understand the magnitude, timescale, drivers and impacts of this variability if we are to correctly attribute observed trends in the North Atlantic circulation, and develop robust early warning systems of, and plan adaptation to, future change. In CLAM we aim to utilise a network of robustly calibrated and verified absolutely dated sclerochronological proxy archives from NW Scotland, N. Iceland and the Gulf of Maine, together with high-resolution climate models, to investigate the mechanisms and forcings driving variability in the circulation patterns of the North Atlantic over the last millennium. This work builds on two exciting pieces of research, the first which presents the first ever annually resolved marine palaeoclimate record spanning the last 1000 years, and finds the ocean to be leading the land records throughout much of this period (Reynolds et al., in review), and the second, which brings this information together with the PMIP3 last millennium simulations, to show that bivalves are recording GIN sea destiny variability, that this is associated with AMOC change, and that this AMOC change can explain much of the previously unexplained Atlantic climate variability of the last Millennium (Halloran et al., in review).
The project is a collaborative effort between The Universities of Exeter, Cardiff and Bangor, and the Met Office. At the University of Exeter, we will be running idealised climate model simulations to attribute the reconstructed variability to a variety of hypothesised forcing mechanisms, quantifying the potential roles of salinity and temperature in forcing the reconstructed oxygen isotope variability, and using simulations of the last millennium to help interpret the exciting new annually resolved Atlantic network of bivalve oxygen isotope data.
Refernces:
Reynolds, D.J., Scourse, J.D., Halloran, P.R. Nederbragt, A.,
Wanamaker, A.D., Butler, P.G., Richardson, C.A., Heinemeier, J.,
Eiriksson, J. , Knudsen, K.L. & Hall, I.R., Annually Resolved
North Atlantic Marine Climate Over The Last Millennium, Nature Communication, In Review
Paul R. Halloran, David J. Reynolds, Ian R. Hal2, James, D. Scourse,
Ben B.B. Booth, Alessio Bozzo, Nick Dunstone, Mathew Menary, Steven
Phipps, Andrew P. Schurer, Tetsuo Sueyoshi, Tianjun Zhou, External
Forcing of the Atlantic Meridional Overturning Circulation and North
Atlantic Temperatures Over the Last Millennium, Nature, In Review