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Climate change in polar regions

David N. Thomas, G.E. (Tony) Fogg, Peter Convey, Christian H. Fritsen, Josep-Maria Gili, Rolf Gradinger, Johanna Laybourn-Parry, Keith Reid, and David W.H. Walton

in The Biology of Polar Regions

The polar regions have undergone major changes in configuration of land masses and climate over millions of years. However, it is the geologically brief period beginning around 120,000 years before ... More

The polar regions have undergone major changes in configuration of land masses and climate over millions of years. However, it is the geologically brief period beginning around 120,000 years before present (BP), including a warm interglacial followed by the Würm glaciation and then the interglacial in which we now live, which is most relevant. This chapter discusses changes during geological time: the ice ages; biological responses to long-term changes; and present-day global climate change and polar regions.Less

Icehouse Earth

Toby Tyrrell

in On Gaia: A Critical Investigation of the Relationship between Life and Earth

This chapter compares the life that evolution produced during the past cold and warm climates of long duration. The dominant climatic state of the last several million years has been ice ages. James ... More

This chapter compares the life that evolution produced during the past cold and warm climates of long duration. The dominant climatic state of the last several million years has been ice ages. James Lovelock has argued that these are a more favorable state for life on Earth than the present interglacials. This does not, however, sit well with various observations. During ice ages: (i) there was less land free of ice; (ii) much of the most productive parts of the ocean, the shelf seas, were turned into dry land by lower sea level; and (iii) the total mass of carbon locked up in vegetation and soils was only about half as much as today. Not only were ice ages unfortunate episodes for life on Earth, but also, conversely, the Earth during the Cretaceous was possibly even more congenial than it is today, although the evidence is not conclusive on this point.Less

The Ocean’s Memory of the Ice Ages: The Endless Cycles of Climate Change

Wolf H. Berger

in Ocean: Reflections on a Century of Exploration

This chapter discusses the discovery of the Great Ice Age, focusing on the ice-age memories of the ocean and ice-age fluctuations. It first introduces fundamental concepts regarding ... More

This chapter discusses the discovery of the Great Ice Age, focusing on the ice-age memories of the ocean and ice-age fluctuations. It first introduces fundamental concepts regarding glacial–interglacial fluctuations in oceanic and climatic conditions, and then discusses the Great Ice Age and fossil preservation. The chapter analyzes microfossils, which provided clues about the changes in the conditions of surface waters in response to climate change and changes in the isotopic composition of seawater. It also discusses ice-age cycles, including the last ice age and how it ended.Less

The Little Ice Age Crisis of the Ottoman Empire: A Conjuncture in Middle East Environmental History

Sam White

in Water on Sand: Environmental Histories of the Middle East and North Africa

After centuries of conquest and expansion, the Ottoman Empire descended into crisis in the 1590s as a widespread uprising known as the Celali Rebellion ushered in decades of economic dislocation, ... More

After centuries of conquest and expansion, the Ottoman Empire descended into crisis in the 1590s as a widespread uprising known as the Celali Rebellion ushered in decades of economic dislocation, military setbacks, and flight and chaos in the countryside. This chapter offers a fundamental reinterpretation of this social unrest, combining original archival research with new data and perspectives from climatology to present the crisis as a critical conjuncture of ecological pressures and deteriorating climate brought on by the Little Ice Age. Already by the 1580s, rapid population growth had placed the empire's elaborate provisioning systems under stress. As the Ottomans fell into a grueling war with the Habsburgs in 1593, the Eastern Mediterranean also descended into its worst drought in six centuries, punctuated by the coldest winters in memory. A widespread epizootic proved fatal to imperial stability, as unbearable wartime requisitions combined with famine and desperation to foment rebellion. The depopulation of the countryside and the nomadic invasions that followed unraveled centuries of settlement and demographic expansion. This chapter thus illustrates some of the major environmental forces at work in the Ottoman Middle East and the power of environmental history to reinterpret the region's past.Less

Crop management in the classical and medieval periods

Denis J. Murphy

in People, Plants and Genes: The Story of Crops and Humanity

The classical and medieval periods of 1800 BCE to 1500 CE were characterized by some limited technical innovation in agriculture, but little progress was made in crop improvement as global ... More

The classical and medieval periods of 1800 BCE to 1500 CE were characterized by some limited technical innovation in agriculture, but little progress was made in crop improvement as global populations ceased their expansion, which had been occurring since the early Holocene. Babylonian and Assyrian imperial rulers established a much-copied precedent of introducing new crops from conquered regions and in producing manuals for agricultural management. From 500 to 50 BCE, Greek naturalists began systematically to study plant biology and publish their findings, but this first blooming of scientific methodology proved short lived. Later cultures tended to reinterpret old knowledge rather than create it anew. From 700 CE, the expanding Muslim empires introduced many improvements into Mediterranean farming from the Near East, most notably in their Iberian realm of Al Andalus. Medieval farming in Europe was relatively stagnant and declined further after 1320 CE during the Little Ice Age.Less

Setting the Stage

David J. Meltzer

in The Great Paleolithic War: How Science Forged an Understanding of America's Ice Age Past

By the early 1800s Georges Cuvier had proven animal extinction and Louis Agassiz a onetime Ice Age, putting in place key elements for telling past time. A new dimension of archaeology opened in ... More

By the early 1800s Georges Cuvier had proven animal extinction and Louis Agassiz a onetime Ice Age, putting in place key elements for telling past time. A new dimension of archaeology opened in mid-century with discoveries in Europe of stone artifacts associated with extinct animals in glacial deposits. The earliest traces of humanity abruptly plunged deep into the Pleistocene. The Smithsonian's Joseph Henry introduced those discoveries to America, and spurred him to send out a circular in 1862 to the institutions network of correspondents explaining what sorts of evidence to seek that might reveal a deep human antiquity on this continent. There had been occasional finds hinting at such, and so too did the great diversity of Native American languages and culture. Over the next decade the archaeological collections of the Smithsonian grew rapidly, but while some of the artifacts appeared to match “Stone Age” artifacts of Europe, similar artifacts were still being made by Native Americans, rendering their antiquity uncertain without geological evidence. By the late 1870s Henry was skeptical any would be found. Yet, just as he was abandoning hope a onetime physician was finding what appeared to be traces of Paleolithic artifacts in the Delaware Valley.Less

Snowball earth? (1835–40)

in Worlds Before Adam: The Reconstruction of Geohistory in the Age of Reform

The explanatory problems raised by erratics and scratched bedrock remained at the heart of debates about geohistory as a whole, because they impinged crucially on the problems of reconstructing the ... More

The explanatory problems raised by erratics and scratched bedrock remained at the heart of debates about geohistory as a whole, because they impinged crucially on the problems of reconstructing the part of geohistory closest to the present world. This chapter describes how these problems came much closer to being resolved. The three rival explanations of erratic blocks and scratched bedrock surfaces—that they were traces of a “diluvial” mega-tsunami, or of submergence in a sea with drifting and melting icebergs, or of vast glaciers extending from a newly elevated mountain range—were joined in the later 1830s by a fourth and even more sensational possibility. Louis Jean Rodolphe Agassiz proposed that the whole earth—or, at least, the northern hemisphere as far south as north Africa—had been covered by a static sheet of ice during an “Ice Age,” before the sudden and geologically recent upheaval of the Alps; the latter had merely produced a tilted surface of ice, down which the erratics could slide from Alps to Jura. Only after this had a warming climate melted the static ice-sheet and turned its remnants into slowly retreating valley glaciers. Agassiz integrated this “glacial theory” into his larger picture of geohistory, by suggesting that the Ice Age had been just the most recent in a succession of catastrophic climatic crises in the history of life.Less

Gaia and Glaciation: Lipalian (Vendian) Environmental Crisis

Mark A. S. McMenamin

in Scientists Debate Gaia: The Next Century

The Lipalian or Vendian Period, which occurred 600–541 million years ago, begins and ends with global environmental perturbations. It begins as the worst glaciation on record draws to a close. It ... More

The Lipalian or Vendian Period, which occurred 600–541 million years ago, begins and ends with global environmental perturbations. It begins as the worst glaciation on record draws to a close. It ends with a sudden appearance of abundant skeletonized animals that mark the beginning of Cambrian ecology. Several key events in Earth history occur during the Lipalian, bracketed between severe glaciation and the initiation of modern marine ecosystems. The most notable of these events is the appearance of an unusual and conspicuous marine biota, the “Garden of Ediacara.” This biota appears to have characteristics inherited from its sojourn beneath the ice. This chapter examines the role the cryophilic biota, consisting largely of cyanobacteria and chryosphyte and chlorophyte algae, may have played in ending the great ice age. It is hypothesized here that these microbes induced albedo reductions and other changes that rapidly improved global climate.Less

A Framework for Understanding Environmental Change

David E. Anderson, Andrew S. Goudie, and Adrian G. Parker

in Global Environments through the Quaternary: Exploring Evironmental Change

This chapter presents ideas that have evolved around the environmental changes in the world in the Quaternary period, or the last 2.6 million years. It recounts the discovery of the Ice Age and the ... More

This chapter presents ideas that have evolved around the environmental changes in the world in the Quaternary period, or the last 2.6 million years. It recounts the discovery of the Ice Age and the establishment of climatic and sea level fluctuations in the Pleistocene and the Holocene. It also includes an outline of the history of the Earth's climate and the fundamental concepts in the way the past environments are reconstructed and interpreted.Less

Climate wobbles

Tim Lenton and Andrew Watson

in Revolutions that made the Earth

This chapter shows how planetary cooling has culminated in a series of periodic glaciations of the Northern hemisphere – the recent ‘ice ages’ – which have become progressively longer and deeper. ... More

This chapter shows how planetary cooling has culminated in a series of periodic glaciations of the Northern hemisphere – the recent ‘ice ages’ – which have become progressively longer and deeper. Although they are paced by variations in the Earth's orbit, they are increasingly dominated by internal oscillations and amplifying feedbacks. The ice ages illustrate the tightly coupled behaviour of the Earth system, indicating that the climate system which we have evolved in is unusually sensitive. At these time scales, oscillations of climate that are paced by the orbital wobbles of the Earth, known as the Milankovitch cycles, become very apparent. The wobbles occur because the Earth's orbit around the sun does not repeat exactly each year but is subject to variations, due ultimately to the presence of other bodies in the solar system.Less

Origin of the Evergreen Forests

E. C. Pielou

in The World of Northern Evergreens

This chapter addresses two questions that have engaged the interests of ecologists and motivated years of research: Where has the forest come from? And why are the great majority of its trees ... More

This chapter addresses two questions that have engaged the interests of ecologists and motivated years of research: Where has the forest come from? And why are the great majority of its trees conifers rather than deciduous, broadleafed trees? With regards to the first question, the only certain answer is that the trees in the area under study, the area that was ice-covered at the end of the last ice age, must have descended from ancestors that lived elsewhere. For the second question, the success of evergreen conifers vis-à-vis broadleafs in the north probably has less to do with the effect of cold on the trees, and more to do with its effects on the soil.Less

Taking Stock for the Future (1840–45)

in Worlds Before Adam: The Reconstruction of Geohistory in the Age of Reform

The narrative in this book has been brought to an end in the mid-1840s, with the arguments over glacial extension and the putative Ice Age still in full swing, as they would continue to be for many ... More

The narrative in this book has been brought to an end in the mid-1840s, with the arguments over glacial extension and the putative Ice Age still in full swing, as they would continue to be for many years to come. But the glacial debate was traced far enough to illustrate its decisive role in the broader story of the transformation of the earth sciences by the penetration of geohistorical ways of practicing them. The most important point about the controversy over the Ice Age was that any such episode in the geologically recent past was totally unexpected by leading geologists of all stripes. Equally unexpected was the complex story of the history of life that had been pieced together during the quarter-century covered by the present volume. Based initially on Smithian stratigraphy, vastly enlarged and deepened by the geohistorical perspective inspired by Cuvier, and brought to maturity by geologists such as Smith's nephew Phillips, this research disclosed a history of life that, while certainly directional and even “progressive,” could not have been predicted in any detail from such grand theoretical schemes as Lamarck's transformism.Less

On Causality and Ice Age Deglaciations

Alexandre Casanovas and Vicent Gómez

in Scientists Debate Gaia: The Next Century

This chapter discusses the most important of several factors that influence ice ages—solar forcing. Others, such as ocean circulation, are consequences of uneven solar radiation. The complexity of ... More

This chapter discusses the most important of several factors that influence ice ages—solar forcing. Others, such as ocean circulation, are consequences of uneven solar radiation. The complexity of the orbital movement induces a complex distribution of the solar radiation over time over the globe. Complex insolation is related here with ODP site 659 sea core and Vostok ice core data. This chapter also suggests the following Gaian scenario: clathrates accumulated during the long cold periods in tropical oceans become unstable as the ocean water warms, liberating greenhouse gases that fire the Antarctica deglaciation. This contribution is decisive at locations where the oceans cannot directly influence, such as over dry continents. The Vostok record helps us to confirm this issue for Antarctica.Less

Cute and Fuzzy Dinosaurs

Ray Zone

in 3-D Revolution: The History of Modern Stereoscopic Cinema

The making of and world-wide boxoffice success of the 20th century Fox film Ice Age: Dawn of the Dinosaurs in 3D is analysed. The basis of its appeal and its international performance is discussed ... More

The making of and world-wide boxoffice success of the 20th century Fox film Ice Age: Dawn of the Dinosaurs in 3D is analysed. The basis of its appeal and its international performance is discussed along with an interview with stereographer Jayme Wilkinson.Less

The Deicing of the North

Charles Officer and Jake Page

in A Fabulous Kingdom: The Exploration of the Arctic

This chapter examines the factors that contribute to the deicing of Arctic, such as climate change, El Niño and La Niña, and the varying age of the ice. The Earth's average temperature is rising and ... More

This chapter examines the factors that contribute to the deicing of Arctic, such as climate change, El Niño and La Niña, and the varying age of the ice. The Earth's average temperature is rising and falling from year to year, with an overall upward trend. This trend is associated with climate change which causes the Arctic to shrink. This shrinking is caused by local phenomenal weather conditions—caused by El Niños and La Niñas. These weather conditions affect the polar temperature. The chapter also discusses the link between the age of ice and the deicing of the North Pole.Less

Prologue to History

Ruth H. Sanders

in The Languages of Scandinavia: Seven Sisters of the North

The earliest Modern humans settled around 8100 BC in the very far north of Fennoscandia, in northern Finnish Lapland, on the border with Norway. The settlers seem to have come from the Pontic steppes ... More

The earliest Modern humans settled around 8100 BC in the very far north of Fennoscandia, in northern Finnish Lapland, on the border with Norway. The settlers seem to have come from the Pontic steppes (today western Ukraine and Kazakhstan). On the Danish and Norwegian-Swedish peninsulas the earliest post-Ice age settlers were probably migrants from the northwestern coasts of the European continent. These migrations of peoples from the east and from the west, settled what is today Denmark, Norway, Sweden, and Finland. The genetic profile of the modern populations may be plotted on an east-west gradient, with the Sámi people, though still predominantly western, the most weighted toward an eastern profile, which accords with what we know about settlement movements.Less

Amazonian Biogeography as a Test for Gaia

Axel Kleidon

in Scientists Debate Gaia: The Next Century

This chapter discusses the climatic conditions during the last ice age and how they were considerably different from today. The chapter starts by providing a quantifiable definition of “beneficial to ... More

This chapter discusses the climatic conditions during the last ice age and how they were considerably different from today. The chapter starts by providing a quantifiable definition of “beneficial to life.” This is defined as the mean gross carbon uptake of the biota which measures biotic activity. This definition is then applied to a set of climate model simulations of the last ice age in which the extent to which vegetation is capable of recycling soil moisture is modified. A larger capacity to recycle moisture leads to less continental aridity, suggesting higher carbon uptake and thus a more “beneficial” climate for life. This effect is particularly strong in the tropical parts of South America. At the same time that aridity is reduced, surfaces are cooler through enhanced evapotranspiration. This suggests that a definition of Gaia based on optimizing environmental conditions for biotic activity seems more appropriate than a definition based on homeostasis.Less

Tedious Calculations of Extraordinary Interest

James Lawrence Powell

in Four Revolutions in the Earth Sciences: From Heresy to Truth

This chapter focuses on scientific endeavors to calculate how much radiation the carbon dioxide in the Earth's atmosphere absorbs and so determine the effect of changes in atmospheric carbon dioxide ... More

This chapter focuses on scientific endeavors to calculate how much radiation the carbon dioxide in the Earth's atmosphere absorbs and so determine the effect of changes in atmospheric carbon dioxide on global temperatures. The Sun's rays shine not only in the visible part of the spectrum but over a range from infrared to ultraviolet. Since the atmosphere absorbs infrared radiation rising from the Earth's surface, it must also absorb infrared rays entering the atmosphere from the Sun. To understand the Earth's heat budget, it is necessary to know how much heat the Sun provides before its rays begin to be affected by the atmosphere. In 1867, Samuel Pierpont Langley set out to measure the solar constant and found that water vapor in the atmosphere indeed absorbs much of the incoming infrared radiation. Svante Arrhenius used Langley's data to estimate the amount of radiation absorbed by atmospheric carbon dioxide and to determine whether the effect of changes in atmospheric carbon dioxide on global temperatures were enough to cause an ice age.Less

In the Line of Fire

Michael E. Mann

in The Hockey Stick and the Climate Wars: Dispatches from the Front Lines

This chapter explains how the hockey stick emerged as a fundamental icon in the assault against the scientific case for human-caused climate change after it was displayed in the IPCC Third Assessment ... More

This chapter explains how the hockey stick emerged as a fundamental icon in the assault against the scientific case for human-caused climate change after it was displayed in the IPCC Third Assessment Report's Summary for Policy Makers in 2001. Thrust into the limelight, the hockey stick would be displayed in public lectures by IPCC chairman Sir John Houghton of the UK and appear in books written about climate change. Vice President Al Gore cited the findings of the hockey stick study, known as MBH99, in a number of his speeches on climate change during 1999. In the years following publication of the hockey stick, a healthy scientific debate developed within the paleoclimate research community over the details, such as how cold the Northern Hemisphere was on the whole during the Little Ice Age, or how warm it was at the height of the medieval climate anomaly/medieval warm period. The chapter also discusses the campaign launched by climate change deniers to discredit the author's hockey stick paper.Less