Harvesting the biosphere : what we have taken from nature

317 Pages·2013·3.212 MB·English

by  Vaclav Smil

Harvesting the Biosphere
Also by Vaclav Smil
China ’ s Energy
Energy in the Developing World (edited with W. Knowland)
Energy Analysis in Agriculture (with P. Nachman and T. V. Long II)
Biomass Energies
The Bad Earth
Carbon Nitrogen Sulfur
Energy Food Environment
Energy in China’ s Modernization
General Energetics
China ’ s Environmental Crisis
Global Ecology
Energy in World History
Cycles of Life
Energies
Feeding the World
Enriching the Earth
The Earth ’ s Biosphere
Energy at the Crossroads
China ’ s Past, China’ s Future
Creating the 20th Century
Transforming the 20th Century
Energy: A Beginner’ s Guide
Oil: A Beginner’ s Guide
Energy in Nature and Society
Global Catastrophes and Trends
Why America Is Not a New Rome
Energy Transitions
Energy Myths and Realities
Prime Movers of Globalization
Japan ’ s Dietary Transition and Its Impacts ( with K. Kobayashi)
Harvesting the Biosphere
What We Have Taken from Nature
Vaclav Smil
The MIT Press
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London, England
© 2013 Massachusetts Institute of Technology
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Library of Congress Cataloging-in-Publication Data

Smil, Vaclav.
Harvesting the biosphere : what we have taken from nature / Vaclav Smil.
p. cm.
Includes bibliographical references and index.
ISBN 978-0-262-01856-2 (hardcover : alk. paper)
1. Biomass. 2. Biosphere. 3. Natural resources— Accounting. 4. Environmental auditing. 5. Earth — Surface.
I. Title.
TP360.S55 2013
333.95 — dc23
2012021381

10 9 8 7 6 5 4 3 2 1
Contents

Preface vii
I The Earth’ s Biomass: Stores, Productivity, Harvests 1
1 Biomass: Defi nitions and Compositions 5
2 Biomass Stores: Means and Extremes 15
3 Biomass Productivities 31
4 Phytomass Harvests 41
5 Zoomass Harvests 51
6 Land Cover and Productivity Changes 59
II History of the Harvests: From Foraging to Globalization 65
7 The Evolution of Foraging 71
8 Crops and Animals 103
9 Biomass Fuels and Raw Materials 131
III Adding Up the Claims: Harvests, Losses, and Trends 151
10 Changing Land Cover and Land Use 1 57
11 Harvesting the Biosphere 183
12 Long-Term Trends and Possible Worlds 221
Scientifi c Units and Prefi xes 253
References 255
Subject Index 297
Species Index 305

Preface
The Earth’ s biosphere— that thin envelope of life permeating the planet ’ s hydro-
sphere, the lowermost part of its atmosphere, and a small uppermost volume of its
lithosphere— is of surprisingly ancient origin: the fi rst simple organisms appeared
nearly four billion years ago (the planet itself was formed about 4.6 billion years
ago), metazoan life (the fi rst multicellular organisms belonging to the kingdom of
animals) is more than half a billion years old, and complex terrestrial ecosystems
have been around for more than 300 million years. Many species have exerted
enormous infl uence on the biosphere ’ s character and productivity, none more so
than (on the opposite ends of the size spectrum) oceanic cyanobacteria and the large
trees of the tropical, temperate, and boreal forests. But no species has been able to
transform the Earth in such a multitude of ways and on such a scale as Homo
sapiens — and most of these transformations can be traced to purposeful harvesting
or destruction of the planet ’ s mass of living organisms and reduction, as well as
improvement, of their productivity.
These transformations long predate the historical period that began about fi ve
millennia ago and was preceded by millennia of gradual domestication of wild plant
and animal species and by the evolution of sedentary agriculture. Humans eventually
created entirely new landscapes of densely populated areas through intensive agri-
culture, industrialization, and urbanization. These processes reached an unprece-
dented intensity and extent beginning in the latter half of the nineteenth century as
industrialization was accompanied by improved food supplies, greater personal
consumption, expanded trade, and a doubling of the global population in 100 years
(from nearly 1.3 billion in 1850 to 2.5 billion in 1950), followed by a 2.4-fold
increase (to six billion) by the year 2000. Fossil fuels have energized this latest,
industrial and postindustrial stage of human evolution, whose accomplishments
would have been impossible without tapping an expanding array of other mineral
resources or deploying many remarkable technical innovations.
viii Preface
But the metabolic imperatives of human existence remain unchanged, and har-
vesting phytomass for food is still the quintessential activity of modern civilization.
What has changed is the overall supply and the variety and quality of typical diets:
increasing populations and improved standards of living have meant greater har-
vests of the Earth ’ s primary production, digestible photosynthates suitable for con-
suming directly as food crops or indirectly (after feed crops and natural vegetation
are consumed by domesticated or wild vertebrates) as the milk, eggs, and meat of
terrestrial animals or as the highly nutritious tissues of aquatic invertebrates, fi shes,
and mammals. Harvests of woody phytomass were initially undertaken to feed the
hominin fi res and make simple weapons. Sedentary cultures had a much greater
demand for fi rewood (they burned crop residues, too), as well as for wood as a
principal construction material. Industrialization increased such demands, and
acquiring wood for pulp has been the third major motivation for tree harvests since
the latter half of the nineteenth century.
The demand for food could not be met just by increasing yields but required the
substantial conversion of forests, grasslands, and wetlands to new cropland. This
led to a net loss of phytomass stores as well as to losses of overall primary produc-
tion; in turn, some of the best agricultural lands were lost to expanding cities and
industrial and transportation infrastructures. Similar losses of potential productivity
have followed as substantial areas of natural ecosystems have been converted to
pastures or affected by the grazing of domesticated herbivores, and as secondary
tree growth or inferior woodlands replaced original forests.
Food, feed, fi ber, and wood are the key phytomass categories that must be har-
vested to meet basic human needs. Harvests of furs, ornamental and medicinal
plants, and companion animals may be important for their impact on particular
ecosystems and species, but their overall removal has been (in mass terms) much
smaller than the aggregate of many uncertainties that complicate the quantifi cation
of phytomass belonging to the four principal categories. The steeply ascending phase
of phytomass harvests has yet to reach its peak, but I do not forecast when it may
do so. Instead, I will review the entire spectrum of harvests and present the best
possible quantifi cations of past and current global removals and losses as a way to
assess the evolution and extent of human claims on the biosphere. Although some
of the claims can be appraised with satisfactory accuracy, in many other cases phy-
tomass accounting can do no better than suggest the correct orders of magnitude.
But even that is useful, as our actions should be guided by the best available quan-
tifi cations rather than by strong but unfounded qualitative preferences or wishes.
I
The Earth’ s Biomass: Stores, Productivity, Harvests