Table Of ContentGlobal Change – The IGBP Series
3
Berlin
Heidelberg
New York
Hong Kong
London
Milan
Paris
Tokyo
W. Steffen · A. Sanderson · P.D. Tyson · J. Jäger · P.A. Matson · B. Moore III
F. Oldfield · K. Richardson · H.J. Schellnhuber · B.L. Turner II · R.J. Wasson
Global Change
and the Earth System
A Planet Under Pressure
With 258 Figures
123
Authors
Steffen, Will Oldfield, Frank
IGBP Secretariat, Department of Geography,
Royal Swedish Academy of Sciences, Stockholm University of Liverpool, UK
Sanderson, Angelina Richardson, Katherine
IGBP Secretariat, Department of Marine Ecology,
Royal Swedish Academy of Sciences, Stockholm Århus University, Denmark
Tyson, Peter Schellnhuber, H. John
Climatology Research Group, Tyndall Centre for Climate Change Research,
University of the Witwatersrand, Johannesburg, South Africa University of East Anglia, Norwich, UK,
and
Jäger, Jill Potsdam Institute for Climate Impact Research, Germany
Coordinator, Turner, B.L. II
Initiative on Science and Technology for Sustainability
Graduate School of Geography
Matson, Pamela & George Perkins Marsh Institute,
Clark University, MA, USA
School of Earth Sciences
Stanford University, CA, USA Wasson, Robert J.
Moore III, Berrien Centre for Resource and Environmental Studies
The Australian National University, Canberra
Institute for the Study of Earth, Oceans and Space (EOS),
University of New Hampshire, Durham, NH, USA
Library of Congress Control Number: 2005927608
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Preface
The relationship of humans with the Earth’s environment has changed throughout
the evolution of Homo sapiens and the development of societies. For virtually all of
human existence on the planet, interaction with the environment has taken place at
the local, or at most the regional, scale, except perhaps for one example in which
regional-scale human activities were repeated to create global consequences in
concert with climate change – the Holocene megafauna extinction. Apart from this
possible example, the environment at the scale of the Earth as a whole – the passing
of the seasons, the vagaries of weather and climate, the ebbing and flowing of river
systems and glaciers, the rich diversity of life in all its forms – has been a framework
within which humans have been able to evolve and develop social structures, sub-
ject only to the great forces of nature and the occasional perturbations of extrater-
restrial origin. The Earth’s environment has been a bountiful source of resources as
well as a remarkably accommodating life support system that has allowed human
civilisations to develop and flourish.
This book focuses on the profound transformation of Earth’s environment that
is now apparent, a transformation owing not to the great forces of nature or to
extraterrestrial sources but to the numbers and activities of people – the phenom-
enon of global change. Begun centuries ago, this transformation has undergone a
profound acceleration during the second half of the twentieth century. During the
last 100 years the population of humans soared from little more than one to six
billion and economic activity increased nearly 10-fold between 1950 and 2000. The
world’s population is more tightly connected than ever before via globalisation of
economies and information flows. Half of Earth’s land surface has been domesti-
cated for direct human use and nearly all of it is managed by humans in one way or
another. Most of the world’s fisheries are fully or over-exploited and little pristine
coastline exists outside of the high latitudes. The composition of the atmosphere –
greenhouse gases, reactive gases, aerosol particles – is now significantly different
from what it was a century ago. The Earth’s biota is now experiencing the sixth great
extinction event, but the first caused by another species: Homo sapiens. The evi-
dence that these changes are affecting the basic functioning of the Earth System,
particularly the climate, grows stronger every year. Evidence from several millenia
shows that the magnitude and rates of human-driven changes to the global environ-
ment are in many cases unprecedented. There is no previous analogue for the
current operation of the Earth System.
This book sets out what is known about global change and the nature of the Earth
System. It addresses a number of important but difficult questions. How did the
Earth System operate in the absence of significant human influence? How can
human-driven effects be discerned from those due to natural variability? What are
the implications of global change for human well-being? How robust is the Earth
System in the face of these new internal forces of change? Can human activities
trigger abrupt and potentially irreversible changes to which adaptation would be
impossible? How serious is this inadvertant human experiment with its own life
support system? By raising and attempting to address these questions in this vol-
ume, the authors hope to give some direction to the future of Earth System science
VI Preface
and to challenge the global change research community to find answers to these
questions.
Such an undertaking as this volume could not have been possible without the
active involvement of a large number of people. The book’s production has truly
been a community effort. The project began as a synthesis of a decade of research
undertaken under the auspices of the International Geosphere-Biosphere Pro-
gramme (IGBP) but quickly grew to encompass contributions from the global change
research community more generally, particularly IGBP’s partner international pro-
grammes: DIVERSITAS, an international programme of biodiversity science; the
International Human Dimensions Programme on Global Environmental Change
(IHDP); and the World Climate Research Programme (WCRP). The acknowledge-
ments section at the end of this volume is thus unusually long. The authors hope that
the many contributions to the book have been properly acknowledged; any inad-
vertant oversights are the responsibility of the authors and are regretted.
Finally, this volume stands as one contribution of the many required to build the
knowledge base to support the long-term, sustainable existence of the human en-
terprise on planet Earth. It argues that a truly global system of science is needed for
coping with the challenges that lie ahead.
Will Steffen, Angelina Sanderson, Peter Tyson, Jill Jäger, Pamela Matson,
Berrien Moore III, Frank Oldfield, Katherine Richardson, H. John Schellnhuber,
B.L. Turner II, Robert Wasson
Stockholm, August 2003
Contents
1 An Integrated Earth System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 A Research Agenda to Meet the Challenge of the Future . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 The Earth as a System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 The Nature of Global Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Objectives and Structure of the Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2 Planetary Machinery:
The Dynamics of the Earth System Prior to Significant Human Influence . . 11
2.1 The Natural Dynamics of the Earth System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2 New Insights in Temporal Variability of the Earth System . . . . . . . . . . . . . . . . . . . . 12
2.2.1 The Long-Term Envelope of Natural Self-Regulation . . . . . . . . . . . . . . . . . . 12
2.2.2 Millennial-Scale Oscillations and Abrupt Changes . . . . . . . . . . . . . . . . . . . . . 13
2.2.3 Climate Variability in Interglacial Periods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.2.4 Temporal Variability in the Biota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.3 New Insights into the Role of Biology in Earth System Functioning . . . . . . . . 24
2.3.1 Biogeophysical Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.3.2 Biogeochemical Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.3.3 The Role of Biodiversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2.4 New Insights into Spatial Variability of the Earth System . . . . . . . . . . . . . . . . . . . . . 35
2.4.1 Spatial Patterns of Land Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.4.2 Spatial Patterns of Carbon Sources and Sinks . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.4.3 Trace Gas Exchanges Between Earth’s Surface and the Atmosphere . . . . 47
2.5 New Insights into the Connectivity of the Earth System over Space and Time . 51
2.5.1 Connectivity via the Oceans and their Currents . . . . . . . . . . . . . . . . . . . . . . . . 51
2.5.2 Connectivity via Atmospheric Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
2.5.3 Connectivity via Hydrologic Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
2.5.4 Connectivity via the Biota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
2.5.5 Teleconnections in the Climate System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
2.5.6 Connectivity through Time: The Legacy of Past Disturbance . . . . . . . . . 63
2.6 New Insights into Non-linearities, Surprises and Thresholds
in the Earth System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
2.6.1 Glacial Terminations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
2.6.2 Heinrich and Dansgaard-Oeschger Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
2.6.3 Mega-droughts and Other Extreme Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
2.6.4 The Browning of the Sahara . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
2.7 The Earth System in a Pre-Human Dominated State . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
3 The Anthropocene Era: How Humans are Changing the Earth System . . . . 81
3.1 A Human-Dominated Planet? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.2 Drivers of Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
3.2.1 Sectoral Activities as Drivers of Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
3.2.2 A Systems Approach to the Drivers of Earth System Change . . . . . . . . 90
VIII Contents
3.3 Characterisation of Changes in the Earth System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
3.3.1 The Earth’s Land as Transformed by Human Activities . . . . . . . . . . . . . . . 93
3.3.2 The Atmosphere as Transformed by Human Activities . . . . . . . . . . . . . 100
3.3.3 The Hydrological Cycle as Transformed by Human Activities . . . . 111
3.3.4 Coastal and Marine Environments
as Transformed by Human Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
3.3.5 Biological Diversity as Transformed by Human Activities . . . . . . . . . 118
3.3.6 Alteration of Carbon, Nitrogen, Phosphorus and Sulphur Fluxes . . . 119
3.4 Putting Human-Driven Changes into an Earth System Perspective . . . . . . . 123
3.4.1 Socioeconomic and Cultural Teleconnections . . . . . . . . . . . . . . . . . . . . . . . . 123
3.4.2 Interaction Between Human-Driven Changes
and Natural Variability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
3.4.3 Global Change:
Magnitudes, Rates and Significance of Human Changes . . . . . . . . . . . . 131
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
4 Reverberations of Change:
The Responses of the Earth System to Human Activities . . . . . . . . . . . . . . . . . 143
4.1 Reverberations of Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
4.2 Responses of the Earth System to Fossil Fuel Combustion . . . . . . . . . . . . . . . . . 143
4.2.1 Non-Reactive Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
4.2.2 Reactive Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
4.2.3 Aerosols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
4.3 Response of the Earth System to Land-Use and Land-Cover Change . . . . . 168
4.3.1 The Conversion Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
4.3.2 Effects of Changed Land Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
4.3.3 Intensification of Agriculture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
4.4 Multiple and Interacting Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
4.4.1 Fires in Southeast Asia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
4.4.2 Coral Reefs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
4.5 Integrated Responses of the Earth System to Human Forcing . . . . . . . . . . . . . . 192
4.5.1 The Carbon Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
4.5.2 Nitrogen, Phosphorus, Sulphur Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
4.5.3 The Hydrological Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
4.5.4 The Climate System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
5 Living with Global Change:
Consequences of Changes in the Earth System for Human Well-Being . . . 203
5.1 Consequences of Global Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
5.2 General Approaches for Anticipating the Consequences
of Global Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
5.2.1 The Scenario-Driven Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
5.2.2 Assessment of Consequences Based on Vulnerability . . . . . . . . . . . . . . . 205
5.2.3 Assessment of Vulnerability Using Palaeo-Data . . . . . . . . . . . . . . . . . . . . . . . 209
5.3 Risks to Key Resources for Human Well-Being . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
5.3.1 Quality and Sufficiency of Food . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
5.3.2 Water Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
5.3.3 Air Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
5.3.4 Pests and Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
5.3.5 Amplifying, Damping and Multiple Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
5.4 Risks Facing the Earth System as a Whole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
5.4.1 Catastrophic Failures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
5.4.2 Past Changes, Extreme Events and Surprises . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
5.4.3 Human Perceptions of Global Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
Contents IX
6 Towards Earth System Science and Global Sustainability . . . . . . . . . . . . . . . 255
6.1 From Climate Change to Earth System Science . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
6.2 The Knowledge Base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
6.2.1 Biology in the Earth System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
6.2.2 The Nature of Global Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
6.2.3 Cascading Impacts of Global Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
6.2.4 Thresholds and Abrupt Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
6.2.5 A No-Analogue State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
6.3 Making Earth System Science . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
6.3.1 Questions at the Frontier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
6.3.2 Coping with Complexity and Irregularity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
6.4 The Earth System Science Toolkit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
6.4.1 Palaeo-Science . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
6.4.2 Contemporary Observation and Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . 271
6.4.3 Earth System Experimentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274
6.4.4 Global Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
6.4.5 Integrated Regional Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
6.4.6 Simulating Earth System Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
6.4.7 Global Integration, Synthesis and Communication . . . . . . . . . . . . . . . . . . . 283
6.5 Towards Global Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
6.5.1 Advancing Sectoral Wisdom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
6.5.2 Stewardship of the Earth System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
6.5.3 Challenges of a Changing Earth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
