Foreword
A brief history of paleoclimates
Climate is undeniably a topical issue of utmost importance. It has been the focus of attention
for several decades now, during which the study of ancient climates (paleoclimatology) has
progressed and gained a solid reputation. Currently, this work has become fundamental to our
understanding of how the climate system functions and to validate the models used to establish
future projections. Thanks to the study of past climates, a database documenting a much
greater diversity of climate changes than during recent centuries, has been created. This
diversity makes it possible to test climate models in situations that are vastly different from
those we have known over the last 150 years and, in some cases, for climates that are closer to
those that await us in the future if we apply the conclusions of the Intergovernmental Panel for
Climate Change.
The Earth’s climate changes have always changed over time and will continue to change in
the future. While we are all aware of the weather phenomena that condition our daily lives, few
of us are aware of what climate really is. Climatology is the science that explores the great
variability in meteorological conditions over time and space, throughout history. This word
comes from the Greek word klima meaning inclination, in this case referring to that of the rays
of the Sun. Since the dawn of our civilization, therefore, we have linked the variations in climate
and in the energy received from the Sun in a relationship of cause and effect. For a long time, the
term ‘climate’ was reserved to describe the characteristics of air temperature and precipitation
particular to different parts of the globe. This description was based on meteorological measurements and their averages conducted over a few decades. It is only recently understood that
climate also varies over much longer time scales and therefore concerns more than just the
atmosphere. At present, specialists studying climate and its variations analyze all of the fluid and
solid envelopes of the Earth. Along with the atmosphere, we associate the hydrosphere and the
cryosphere which, together, represent the systems where water exists in solid (snow, glaciers,
and ice sheets) and liquid form (rivers, lakes, and seas), the continents where plate tectonics and
volcanic activity occur, and finally at the surface, the whole living world (biosphere) that
influences nature, the properties of soil cover, and the biogeochemical cycles.
Climatology has evolved from being a descriptive discipline to become a multidisciplinary
science involving five complex systems and their various interactions. It is therefore not surprising that the resulting climate studies vary on scales ranging from the season to millions of
years. Although it is only in the last few decades that this science has exploded, the first
discovery and study of climate change beyond the annual and decadal scales date back to the
eighteenth century. It was at this time that the presence of erratic boulders in the mountainous
landscape became associated for the first time with the massive extension of glaciers. In 1744,
the Grenoble geographer Pierre Martel (1706–1767) reported that the inhabitants of the Chamonix Valley in the Alps attributed the dispersion of roches moutonnées to the glaciers
themselves, which would have extended much further in the past. This was a revolutionary
idea, because until then, most scientists still referred to the myth of the Biblical Flood to explain
landscape structures. This was the case of Horace Benedicte de Chaussure (1740–1799) from
Geneva, the French paleontologist, Georges Cuvier (1769–1832) and the Scottish geologist,
v
A brief history of paleoclimates
Climate is undeniably a topical issue of utmost importance. It has been the focus of attention
for several decades now, during which the study of ancient climates (paleoclimatology) has
progressed and gained a solid reputation. Currently, this work has become fundamental to our
understanding of how the climate system functions and to validate the models used to establish
future projections. Thanks to the study of past climates, a database documenting a much
greater diversity of climate changes than during recent centuries, has been created. This
diversity makes it possible to test climate models in situations that are vastly different from
those we have known over the last 150 years and, in some cases, for climates that are closer to
those that await us in the future if we apply the conclusions of the Intergovernmental Panel for
Climate Change.
The Earth’s climate changes have always changed over time and will continue to change in
the future. While we are all aware of the weather phenomena that condition our daily lives, few
of us are aware of what climate really is. Climatology is the science that explores the great
variability in meteorological conditions over time and space, throughout history. This word
comes from the Greek word klima meaning inclination, in this case referring to that of the rays
of the Sun. Since the dawn of our civilization, therefore, we have linked the variations in climate
and in the energy received from the Sun in a relationship of cause and effect. For a long time, the
term ‘climate’ was reserved to describe the characteristics of air temperature and precipitation
particular to different parts of the globe. This description was based on meteorological measurements and their averages conducted over a few decades. It is only recently understood that
climate also varies over much longer time scales and therefore concerns more than just the
atmosphere. At present, specialists studying climate and its variations analyze all of the fluid and
solid envelopes of the Earth. Along with the atmosphere, we associate the hydrosphere and the
cryosphere which, together, represent the systems where water exists in solid (snow, glaciers,
and ice sheets) and liquid form (rivers, lakes, and seas), the continents where plate tectonics and
volcanic activity occur, and finally at the surface, the whole living world (biosphere) that
influences nature, the properties of soil cover, and the biogeochemical cycles.
Climatology has evolved from being a descriptive discipline to become a multidisciplinary
science involving five complex systems and their various interactions. It is therefore not surprising that the resulting climate studies vary on scales ranging from the season to millions of
years. Although it is only in the last few decades that this science has exploded, the first
discovery and study of climate change beyond the annual and decadal scales date back to the
eighteenth century. It was at this time that the presence of erratic boulders in the mountainous
landscape became associated for the first time with the massive extension of glaciers. In 1744,
the Grenoble geographer Pierre Martel (1706–1767) reported that the inhabitants of the Chamonix Valley in the Alps attributed the dispersion of roches moutonnées to the glaciers
themselves, which would have extended much further in the past. This was a revolutionary
idea, because until then, most scientists still referred to the myth of the Biblical Flood to explain
landscape structures. This was the case of Horace Benedicte de Chaussure (1740–1799) from
Geneva, the French paleontologist, Georges Cuvier (1769–1832) and the Scottish geologist,
v