rapid climate variability was superimposed. The isotopic
measurements of the oxygen in carbonate tests of planktonic
foraminifera and fish teeth provide an estimate of the paleotemperature of the surface waters of the oceans. These data,
as well as studies carried out in continental areas, on palynomorphs, for example, reflect the climate variability of this
period (Ladant and Donnadieu 2016). Thus, d
18 O measurements show that the Turonian had a particularly hot climate,
with sea surface temperatures of between 34 and 37 °C.
However, the d
18
O measurements also show the existence of
a glaciation event lasting less than 200,000 years (Bornemann et al. 2008). The Cretaceous ended with a rapid cooling
just before the major mass extinction of the CretaceousTertiary boundary at 66 Ma, during which nearly 60% of the
species on Earth died out. As for the other crises of the
Phanerozoic, this crisis is synchronous with the establishment
of a large basaltic province, the Deccan traps in India, but
also, with another event, the fall of an extraterrestrial body
into the Gulf of Mexico.
After this crisis, the Earth entered a warm period during
which signs of glaciation disappeared. This period was punctuated by the thermal maximum at the Palaeocene-Eocene
boundary (55 Ma) (Zachos et al. 2001). This was a rapid transient event (at the geological time scale), lasting about 300 ka,
marked by an abrupt increase in temperatures (considered as the
best analogue to current global warming). Tropical flora, but
also turtles, crocodiles, and many mammals were discovered on
the Ellesmere and Axel Heiberg islands in northern Canada.
As early as the Late Eocene (*50 Ma), the Earth experienced gradual cooling with the onset of a new glacial
period around 40 Ma marked by a first stage of development
of the Antarctic ice cap, corresponding probably to the
appearance of glaciers in the Trans-Antarctic chain. This ice
cap grew quickly and reached the coast, as evidenced by
glacial sediments found off the Antarctic continent, dating
from the Eocene-Oligocene boundary (*34 Ma). Numerous
measurements of the isotopic composition of oxygen in the
carbonate tests of benthic foraminifera in sediments collected at different points around the globe confirm a consistent cooling during the Eocene. At the Eocene-Oligocene
boundary, a significant and rapid cooling of the ocean bottom waters occurred, estimated at about 6 °C (Hren et al.
2013). Henceforth, the isotopic ratio of strontium increased
significantly in response to intensified continental erosion.
During the Lower Miocene (23–15 Ma), the global trend
was a slight warming interspersed with brief cooling episodes. Around 14 Ma, rapid cooling led to a new phase of
development of the Antarctic ice sheet. This climate trend
accelerated during the Upper Miocene and the Pliocene. The
development of an ice cap on Greenland probably dates from
the Upper Miocene or the Pliocene, but a high probability of
sea ice on the Arctic Ocean starting from the climate
transition of the Middle Miocene is suggested by the sedimentary facies observed in the Arctic Ocean. This cold climate impacts on the high latitudes of both hemispheres and
provides the necessary conditions for the rapid glacial/
interglacial fluctuations during the Pleistocene (but does not
trigger them).
Paleoclimate indicators can be used to trace the evolution
of the Earth’s climate, so as to gradually refine its contours
and to observe rapid fluctuations superimposed on
longer-term trends. However, there are areas of uncertainty
(as will probably always be the case), especially for the
oldest periods. The causes and mechanisms of these climate
changes at the scale of geological time are manifold. Data
collected in the field allow us to document this evolution
with increasing accuracy, but it is impossible to isolate with
certainty the specific cause or causes of these climate disruptions. Since the 1970s, numerical modeling of climates
has been used, in addition to data, to test the sensitivity of
the climate to different forcings and to try to reproduce
numerically the climate changes observed in the field. Over
long time scales, paleogeographic changes brought about by
plate tectonics have shaped the face of the Earth (Volume 1,
Chap. 2) and are a major forcing of the Earth’s climate
history through their direct effects on atmospheric and
oceanic circulation. We will also see the indirect effects of
paleogeographic changes induced by feedback mechanisms,
in particular on the regulation of the partial pressure of CO 2 ,
another major contributor to the climate system.
Some Consequences of Paleogeographic
Changes on the Earth’s Climate
Continental Drift
Continental drift leads to changes in the latitudinal and
longitudinal distribution of emerged lands with various
consequences for climate. The main ones are: changes in the
distribution of solar radiation received by the continents;
changes in the atmospheric dynamics by the uplift or collapse of mountain ranges or during the formation or
break-up of supercontinents; changes in ocean dynamics
during the opening or closing of basins or ocean passages
(also called seaways), and also indirect effects such as
changes in weathering fluxes that impact on the carbon cycle
(Donnadieu et al. 2004). In the Upper Permian (*260 Ma),
paleoclimate indicators suggest that a warm, dry climate
developed over a large part of Gondwana (southern hemisphere) located between the narrow rainy equatorial band
and the narrow temperate mid-latitude band, below the
theoretical subsidence zone of the Hadley cell. Several
numerical climate simulations made it possible to develop
22 Climate Evolution on the Geological Timescale and the Role …
259
measurements of the oxygen in carbonate tests of planktonic
foraminifera and fish teeth provide an estimate of the paleotemperature of the surface waters of the oceans. These data,
as well as studies carried out in continental areas, on palynomorphs, for example, reflect the climate variability of this
period (Ladant and Donnadieu 2016). Thus, d
18 O measurements show that the Turonian had a particularly hot climate,
with sea surface temperatures of between 34 and 37 °C.
However, the d
18
O measurements also show the existence of
a glaciation event lasting less than 200,000 years (Bornemann et al. 2008). The Cretaceous ended with a rapid cooling
just before the major mass extinction of the CretaceousTertiary boundary at 66 Ma, during which nearly 60% of the
species on Earth died out. As for the other crises of the
Phanerozoic, this crisis is synchronous with the establishment
of a large basaltic province, the Deccan traps in India, but
also, with another event, the fall of an extraterrestrial body
into the Gulf of Mexico.
After this crisis, the Earth entered a warm period during
which signs of glaciation disappeared. This period was punctuated by the thermal maximum at the Palaeocene-Eocene
boundary (55 Ma) (Zachos et al. 2001). This was a rapid transient event (at the geological time scale), lasting about 300 ka,
marked by an abrupt increase in temperatures (considered as the
best analogue to current global warming). Tropical flora, but
also turtles, crocodiles, and many mammals were discovered on
the Ellesmere and Axel Heiberg islands in northern Canada.
As early as the Late Eocene (*50 Ma), the Earth experienced gradual cooling with the onset of a new glacial
period around 40 Ma marked by a first stage of development
of the Antarctic ice cap, corresponding probably to the
appearance of glaciers in the Trans-Antarctic chain. This ice
cap grew quickly and reached the coast, as evidenced by
glacial sediments found off the Antarctic continent, dating
from the Eocene-Oligocene boundary (*34 Ma). Numerous
measurements of the isotopic composition of oxygen in the
carbonate tests of benthic foraminifera in sediments collected at different points around the globe confirm a consistent cooling during the Eocene. At the Eocene-Oligocene
boundary, a significant and rapid cooling of the ocean bottom waters occurred, estimated at about 6 °C (Hren et al.
2013). Henceforth, the isotopic ratio of strontium increased
significantly in response to intensified continental erosion.
During the Lower Miocene (23–15 Ma), the global trend
was a slight warming interspersed with brief cooling episodes. Around 14 Ma, rapid cooling led to a new phase of
development of the Antarctic ice sheet. This climate trend
accelerated during the Upper Miocene and the Pliocene. The
development of an ice cap on Greenland probably dates from
the Upper Miocene or the Pliocene, but a high probability of
sea ice on the Arctic Ocean starting from the climate
transition of the Middle Miocene is suggested by the sedimentary facies observed in the Arctic Ocean. This cold climate impacts on the high latitudes of both hemispheres and
provides the necessary conditions for the rapid glacial/
interglacial fluctuations during the Pleistocene (but does not
trigger them).
Paleoclimate indicators can be used to trace the evolution
of the Earth’s climate, so as to gradually refine its contours
and to observe rapid fluctuations superimposed on
longer-term trends. However, there are areas of uncertainty
(as will probably always be the case), especially for the
oldest periods. The causes and mechanisms of these climate
changes at the scale of geological time are manifold. Data
collected in the field allow us to document this evolution
with increasing accuracy, but it is impossible to isolate with
certainty the specific cause or causes of these climate disruptions. Since the 1970s, numerical modeling of climates
has been used, in addition to data, to test the sensitivity of
the climate to different forcings and to try to reproduce
numerically the climate changes observed in the field. Over
long time scales, paleogeographic changes brought about by
plate tectonics have shaped the face of the Earth (Volume 1,
Chap. 2) and are a major forcing of the Earth’s climate
history through their direct effects on atmospheric and
oceanic circulation. We will also see the indirect effects of
paleogeographic changes induced by feedback mechanisms,
in particular on the regulation of the partial pressure of CO 2 ,
another major contributor to the climate system.
Some Consequences of Paleogeographic
Changes on the Earth’s Climate
Continental Drift
Continental drift leads to changes in the latitudinal and
longitudinal distribution of emerged lands with various
consequences for climate. The main ones are: changes in the
distribution of solar radiation received by the continents;
changes in the atmospheric dynamics by the uplift or collapse of mountain ranges or during the formation or
break-up of supercontinents; changes in ocean dynamics
during the opening or closing of basins or ocean passages
(also called seaways), and also indirect effects such as
changes in weathering fluxes that impact on the carbon cycle
(Donnadieu et al. 2004). In the Upper Permian (*260 Ma),
paleoclimate indicators suggest that a warm, dry climate
developed over a large part of Gondwana (southern hemisphere) located between the narrow rainy equatorial band
and the narrow temperate mid-latitude band, below the
theoretical subsidence zone of the Hadley cell. Several
numerical climate simulations made it possible to develop
22 Climate Evolution on the Geological Timescale and the Role …
259