22
Climate Evolution on the Geological
Timescale and the Role of Paleogeographic
Changes
Frédéric Fluteau and Pierre Sepulchre
Throughout geological time, major climate changes have
marked the history of the Earth (Fig. 22.1). Although paleoclimate markers provide us with the broad outlines of these
changes, their causes could be manifold as feedback mechanisms occur between the different compartments of the
climate system. In a system where the solid and fluid
envelopes are closely linked, understanding the evolution of
Earth’s climates at the scale of geologic time involves
knowing its paleogeographic history. Within this context,
climate modelling is presented as a well-adapted tool to help
to understand the factors causing climate change over geological time. However, modelling a continuous climate
evolution over million-year timescales is out of reach, as it
would require a detailed and reliable knowledge of the
model boundary conditions, e.g. the location of the continents, the topography, the bathymetry as well as the chemical composition of the atmosphere. Prior to the recent
Quaternary period, uncertainties generally tend to increase
regarding these conditions, and our knowledge becomes
increasingly fragmentary the further into the past we go.
Moreover, even with a perfect knowledge of these conditions, several million years simulations are beyond the
computing capabilities of the supercomputers and the codes
used today to simulate climate. This methodological
dilemma is routinely overcome by means of steady-state
simulations, called “snapshot experiments”, which simulate
the response of the climate system to particular boundary
conditions, and which require only a few thousand years of
simulation, corresponding to the time needed to achieve
equilibrium for all compartments of the climate system. The
first step is to establish the boundary conditions so as to
perform a “contextual” simulation of a large geologic time
interval (for example, the late Miocene). One can then study
the impact of paleogeographic or geochemical changes
within this interval via sensitivity experiments in which, for
example, a mountain range is uplifted or lowered, an ocean
passage is opened or closed, the chemical composition of the
atmosphere is changed or the orbital parameters of the Earth
are altered in line with information provided by the geological, geophysical and geochemical data.
In the first part of this chapter, we present the broad
outlines of the climate history of the earth and in the second
part, we provide examples of how the direct and indirect
couplings between the different envelopes, solid, liquid and
gaseous, can be studied through modelling and show how
they contribute to the explanation of the climate history of
the Earth over long time scales.
The Evolution of Climate Over the Past 4.54
Billion Years
Although the Precambrian (4.54–0.54 Ga) represents 88% of
the Earth’s history we only have a very fragmentary
knowledge of the climate during this period. There are very
few records of the first 900 million years of the Earth’s
history (4.5–3.6 Ga). The oldest geological formations discovered in northwestern Canada (Acasta Gneiss) and in
Greenland (Isua Greenstone Belt) are dated at 4 Ga and
3.8 Ga respectively (Valley 2006) but do not provide any
climate constraints. However, the discovery of zircons in
Australia in the Archean metaconglomerates of Mount
Narryer and Jack Hills, dated at 4.4 Ga, is evidence of the
existence of the first granitic proto-continents (sensu lato).
The oxygen isotopic signature (d
18 O) of these zircons (5–
7‰) confirms the presence of liquid water, and certainly of
oceans, 150 million years after the formation of the Earth.
Between 4.3 and 2.8 Ga (Archean), the Earth’s atmosphere
consisted of a mixture of nitrogen and greenhouse gases,
notably carbon dioxide and methane. There was no oxygen.
F. Fluteau (&)
Université de Paris, Institut de Physique du Globe de Paris, CNRS,
75005 Paris, France
e-mail: fluteau@ipgp.fr
P. Sepulchre
Laboratoire des Sciences du Climat et de l’Environnement,
CNRS-CEA-Université de Versailles Saint Quentin en
Yvelines-Université Paris-Saclay, Gif-sur-Yvette, France
© 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_22
255
Climate Evolution on the Geological
Timescale and the Role of Paleogeographic
Changes
Frédéric Fluteau and Pierre Sepulchre
Throughout geological time, major climate changes have
marked the history of the Earth (Fig. 22.1). Although paleoclimate markers provide us with the broad outlines of these
changes, their causes could be manifold as feedback mechanisms occur between the different compartments of the
climate system. In a system where the solid and fluid
envelopes are closely linked, understanding the evolution of
Earth’s climates at the scale of geologic time involves
knowing its paleogeographic history. Within this context,
climate modelling is presented as a well-adapted tool to help
to understand the factors causing climate change over geological time. However, modelling a continuous climate
evolution over million-year timescales is out of reach, as it
would require a detailed and reliable knowledge of the
model boundary conditions, e.g. the location of the continents, the topography, the bathymetry as well as the chemical composition of the atmosphere. Prior to the recent
Quaternary period, uncertainties generally tend to increase
regarding these conditions, and our knowledge becomes
increasingly fragmentary the further into the past we go.
Moreover, even with a perfect knowledge of these conditions, several million years simulations are beyond the
computing capabilities of the supercomputers and the codes
used today to simulate climate. This methodological
dilemma is routinely overcome by means of steady-state
simulations, called “snapshot experiments”, which simulate
the response of the climate system to particular boundary
conditions, and which require only a few thousand years of
simulation, corresponding to the time needed to achieve
equilibrium for all compartments of the climate system. The
first step is to establish the boundary conditions so as to
perform a “contextual” simulation of a large geologic time
interval (for example, the late Miocene). One can then study
the impact of paleogeographic or geochemical changes
within this interval via sensitivity experiments in which, for
example, a mountain range is uplifted or lowered, an ocean
passage is opened or closed, the chemical composition of the
atmosphere is changed or the orbital parameters of the Earth
are altered in line with information provided by the geological, geophysical and geochemical data.
In the first part of this chapter, we present the broad
outlines of the climate history of the earth and in the second
part, we provide examples of how the direct and indirect
couplings between the different envelopes, solid, liquid and
gaseous, can be studied through modelling and show how
they contribute to the explanation of the climate history of
the Earth over long time scales.
The Evolution of Climate Over the Past 4.54
Billion Years
Although the Precambrian (4.54–0.54 Ga) represents 88% of
the Earth’s history we only have a very fragmentary
knowledge of the climate during this period. There are very
few records of the first 900 million years of the Earth’s
history (4.5–3.6 Ga). The oldest geological formations discovered in northwestern Canada (Acasta Gneiss) and in
Greenland (Isua Greenstone Belt) are dated at 4 Ga and
3.8 Ga respectively (Valley 2006) but do not provide any
climate constraints. However, the discovery of zircons in
Australia in the Archean metaconglomerates of Mount
Narryer and Jack Hills, dated at 4.4 Ga, is evidence of the
existence of the first granitic proto-continents (sensu lato).
The oxygen isotopic signature (d
18 O) of these zircons (5–
7‰) confirms the presence of liquid water, and certainly of
oceans, 150 million years after the formation of the Earth.
Between 4.3 and 2.8 Ga (Archean), the Earth’s atmosphere
consisted of a mixture of nitrogen and greenhouse gases,
notably carbon dioxide and methane. There was no oxygen.
F. Fluteau (&)
Université de Paris, Institut de Physique du Globe de Paris, CNRS,
75005 Paris, France
e-mail: fluteau@ipgp.fr
P. Sepulchre
Laboratoire des Sciences du Climat et de l’Environnement,
CNRS-CEA-Université de Versailles Saint Quentin en
Yvelines-Université Paris-Saclay, Gif-sur-Yvette, France
© 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_22
255