29
Rapid Climate Variability: Description
and Mechanisms
Masa Kageyama, Didier M. Roche, Nathalie Combourieu Nebout,
and Jorge Alvarez-Solas
The previous chapters focused on climate variations stemming from factors external to the climate system: tectonics,
orogeny, variations in insolation. Yet the study of glacial
records and marine sediments over the past three decades has
revealed major changes within the climate system over much
shorter time scales than previously envisaged. These abrupt
reorganisations of the climate system, which cannot be
explained by forcings external to the system, are true climate
‘surprises’. They have been the subject of many studies, both
to describe the expression of these events on a global scale
and to model these events and their impacts. This work is
still going on to better characterize and understand this type
of climate variability, called millennial variability, in contrast to the time scales associated with the Milankovitch
forcings (see Chap. 7), or abrupt (rapid) variability, because
the transitions between climate states take place on even
shorter time scales, ranging from ten to one hundred years.
This chapter presents a synthesis of current knowledge on
rapid climate variability.
Rapid Climate Changes During Glacial
Periods: Heinrich and Dansgaard-Oeschger
Events
The Discovery
Abrupt climate changes were first discovered in the context
of the last glacial period (see the review by Hemming 2004).
In 1977, Ruddiman showed that during Marine Isotopic
Stages 4, 3 and 2, large quantities of coarse detrital material
transported by icebergs detaching from the Northern
Hemisphere ice sheets were deposited at the mid-latitudes of
the North Atlantic between 40 and 65° N in a band now
known as the Ruddiman Belt, while the main deposition area
for Stage 5 is closer to Greenland and Newfoundland. The
concentration of detrital material measured in marine sediments is thus linked with the size and expansion of continental ice sheets over the Milankovitch timescale. In 1988,
H. Heinrich showed that six major events of coarse detrital
material deposition occurred in the Ruddiman band during
the last glacial period at intervals of about 10,000 years, and
therefore at time scales shorter than those of Milankovitch.
These six events are often accompanied by a major change
in the composition of assemblages of planktonic foraminifera, with a predominance of the left-coiling
Neogloboquadrina pachyderma polar species, an indicator
of a particularly cold environment. Heinrich initially based
his interpretation of these results on the fact that the period
of 10,000 years is about half a precession cycle. He speculated that the coarse detrital material was transported either
by icebergs (in orbital conditions favoring a ‘cold’ period) or
by the melting of the ice sheets (‘warm’ situation). This
hypothesis did not stand up to more precise dating and
analyses of marine records in the North Atlantic but it shows
that, at the time of this discovery, the variations in orbital
insolation were considered the main contributors to the
evolution of the climate system. At that time, sudden
changes to the system were not envisaged. The discovery
M. Kageyama (&) Á D. M. Roche
Laboratoire des Sciences du Climat et de l’Environnement,
LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, 91191
Gif-sur-Yvette, France
e-mail: masa.kageyama@lsce.ipsl.fr
N. C. Nebout
UMR 7194 CNRS/UPVD/MNHN, HNHP-Histoire Naturelle de
l’Homme Préhistorique, Département Homme et Environnement,
Muséum National d’Histoire naturelle, Paris, France
N. C. Nebout
Institut de Paléontologie Humaine, 1 rue René Panhard, 75013
Paris, France
J. Alvarez-Solas
Departamento de Física de la Tierra y Astrofísica, Facultad de
Ciencias Físicas, Universidad Complutense de Madrid, 28040
Madrid, Spain
J. Alvarez-Solas
Instituto de Geociencias, Consejo Superior de Investigaciones
Científicas-Universidad Complutense de Madrid, 28040 Madrid,
Spain
© Springer Nature Switzerland AG 2021
G. Ramstein et al. (eds.), Paleoclimatology, Frontiers in Earth Sciences,
https://doi.org/10.1007/978-3-030-24982-3_29
405
Rapid Climate Variability: Description
and Mechanisms
Masa Kageyama, Didier M. Roche, Nathalie Combourieu Nebout,
and Jorge Alvarez-Solas
The previous chapters focused on climate variations stemming from factors external to the climate system: tectonics,
orogeny, variations in insolation. Yet the study of glacial
records and marine sediments over the past three decades has
revealed major changes within the climate system over much
shorter time scales than previously envisaged. These abrupt
reorganisations of the climate system, which cannot be
explained by forcings external to the system, are true climate
‘surprises’. They have been the subject of many studies, both
to describe the expression of these events on a global scale
and to model these events and their impacts. This work is
still going on to better characterize and understand this type
of climate variability, called millennial variability, in contrast to the time scales associated with the Milankovitch
forcings (see Chap. 7), or abrupt (rapid) variability, because
the transitions between climate states take place on even
shorter time scales, ranging from ten to one hundred years.
This chapter presents a synthesis of current knowledge on
rapid climate variability.
Rapid Climate Changes During Glacial
Periods: Heinrich and Dansgaard-Oeschger
Events
The Discovery
Abrupt climate changes were first discovered in the context
of the last glacial period (see the review by Hemming 2004).
In 1977, Ruddiman showed that during Marine Isotopic
Stages 4, 3 and 2, large quantities of coarse detrital material
transported by icebergs detaching from the Northern
Hemisphere ice sheets were deposited at the mid-latitudes of
the North Atlantic between 40 and 65° N in a band now
known as the Ruddiman Belt, while the main deposition area
for Stage 5 is closer to Greenland and Newfoundland. The
concentration of detrital material measured in marine sediments is thus linked with the size and expansion of continental ice sheets over the Milankovitch timescale. In 1988,
H. Heinrich showed that six major events of coarse detrital
material deposition occurred in the Ruddiman band during
the last glacial period at intervals of about 10,000 years, and
therefore at time scales shorter than those of Milankovitch.
These six events are often accompanied by a major change
in the composition of assemblages of planktonic foraminifera, with a predominance of the left-coiling
Neogloboquadrina pachyderma polar species, an indicator
of a particularly cold environment. Heinrich initially based
his interpretation of these results on the fact that the period
of 10,000 years is about half a precession cycle. He speculated that the coarse detrital material was transported either
by icebergs (in orbital conditions favoring a ‘cold’ period) or
by the melting of the ice sheets (‘warm’ situation). This
hypothesis did not stand up to more precise dating and
analyses of marine records in the North Atlantic but it shows
that, at the time of this discovery, the variations in orbital
insolation were considered the main contributors to the
evolution of the climate system. At that time, sudden
changes to the system were not envisaged. The discovery
M. Kageyama (&) Á D. M. Roche
Laboratoire des Sciences du Climat et de l’Environnement,
LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, 91191
Gif-sur-Yvette, France
e-mail: masa.kageyama@lsce.ipsl.fr
N. C. Nebout
UMR 7194 CNRS/UPVD/MNHN, HNHP-Histoire Naturelle de
l’Homme Préhistorique, Département Homme et Environnement,
Muséum National d’Histoire naturelle, Paris, France
N. C. Nebout
Institut de Paléontologie Humaine, 1 rue René Panhard, 75013
Paris, France
J. Alvarez-Solas
Departamento de Física de la Tierra y Astrofísica, Facultad de
Ciencias Físicas, Universidad Complutense de Madrid, 28040
Madrid, Spain
J. Alvarez-Solas
Instituto de Geociencias, Consejo Superior de Investigaciones
Científicas-Universidad Complutense de Madrid, 28040 Madrid,
Spain
© Springer Nature Switzerland AG 2021
G. Ramstein et al. (eds.), Paleoclimatology, Frontiers in Earth Sciences,
https://doi.org/10.1007/978-3-030-24982-3_29
405