1School of Environmental Sciences, University of East Anglia, Norwich, UK
2College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
Received: 28 Aug 2009 – Discussion started: 30 Sep 2009
Abstract. We develop and apply a new statistical method of potential analysis for detecting the number of states of a geophysical system, from its recorded time series. Estimation of the degree of a polynomial potential allows us to derive the number of potential wells in a system. The method correctly detects changes in the number of wells in artificial data. In ice-core proxy records of Greenland paleotemperature, a reduction in the number of climate states from two to one is detected sometime prior to the last glacial maximum (LGM), 23–19 kyr BP. This result is also found in analysis of Greenland Ca data. The bifurcation can be interpreted as loss of stability of the warm interstadial state of the Dansgaard-Oeschger (DO) events. The proposed method can be applied to a wide range of geophysical time series exhibiting bifurcations.
Revised: 06 Jan 2010 – Accepted: 10 Feb 2010 – Published: 17 Feb 2010
Livina, V. N., Kwasniok, F., and Lenton, T. M.: Potential analysis reveals changing number of climate states during the last 60 kyr, Clim. Past, 6, 77-82, doi:10.5194/cp-6-77-2010, 2010.