The 1500 Year Quasiperiodicity During the Holocene - Abrupt Climate Change: Mechanisms, Patterns, and Impacts - page 159

The 1500 Year Quasiperiodicity During the Holocene

A. Ruzmaikin and J. Feynman

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA

We investigate the quasiperiodic 1500 year oscillation in climate during the
Holocene and its relation to the Atlantic meridional overturning circulation
(AMOC). Our data analyses of paleodata reveal the nonlinear nature of this
oscillation. The data analysis also indicates that the AMOC has two major equi-
librium states characterized by a weak and a strong meridional flow in accord with

modeling. Based on the results of the data analysis and earlier ideas about the origin
of the 1500 year oscillation, we suggest a conceptual model explaining its origin.
The model includes two basic equilibrium states. Transitions between the states are
driven by noise and the combined action of the ocean centennial variability and the
90 year solar variability. We brie y discuss a relationship of the 1500 year

millennium oscillation to the global warming problem.

1. INTRODUCTION driven by the solar forcing of the same periodicity. However,

the proxies for the solar irradiance variations (C 14 and B 10 ),
as well as the sunspot number reconstructed over 11,000
years, do not show this periodicity at the time when it is
clearly seen in the North Atlantic paleodata [Debret et al.,
2007; Dima and Lohmann, 2009]. The oceanic forcing is
associated with the Atlantic meridional overturning circula-
tion (AMOC), which transports the salty warm water to
high latitudes where it cools, sinks, and returns southward.
A combined solar-ocean forcing has been considered in
attempts to explain the origin of the 1500 year oscillation
in the glacial climate. Thus, Braun et al. [2005] showed that
an intermediate-complexity model could simulate an appar-
ent 1500 year quasiperiodicity in the glacial climate when
forced by periodic inputs of fresh water into the North
Atlantic. As this input, they selected the superposition of
two solar signals: 90 and 210 year cycles (Gleissberg and
de Vries cycles [Feynman and Fougere, 1984; Damon and
Sonnet, 1991; Peristykh and Damon, 2003; Ruzmaikin et al.,
2006]), which are rational fractions (1/17 and 1/7) of the
1500 year period. This mechanism does not involve the
interaction of solar and ocean variabilities. Dima and Loh-
mann [2009] put forward a concept that the 1500 year
variation arises due to a threshold response of the AMOC

Although the Holocene climate is more stable than cli-
mates of preceding glacial-interglacial periods, it displays a
full palette of high- and low-frequency variations. Identify-
ing the timing, spatial distribution, and origin of these varia-
tions is critical for understanding the mechanisms of climate
change. One of the prominent low-frequency variations is
the quasiperiodic 1500 year oscillation originally found in
ice-rafted debris fluctuations in North Atlantic, which have
the quasiperiod 1470 ± 500 years thus amounting to eight
periods over the Holocene [Bond et al., 1997]. The extrema
of this oscillation are often referred to as the “ Bond events ”
and are considered to be related to the glacial Dansgaard-
Oeschger events.
The origin of the 1500 year oscillation, which is even
more prominent in the glacial time than in the Holocene,
remains debatable. Bond et al. [1997] suggested that it is