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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
In our time, the global population has become large enough to cause perceptible environmental changes all over the world. With it, a new science of global change has emerged, mostly as a practical matter to understand and manage the earth’s habitability and create a sustainable environment for some time to come – one which balances the benefits of technological and societal advances with their potential, less desirable side effects. These concerns began with the depletion of the ozone layer and its possible adverse consequences on human health, and have, in recent decades, shifted to climate change driven by ongoing global warming.
Why are these global changes occurring? How will they affect our lives? If we find the effects undesirable, what should we do? This book will attempt to answer these questions. It will show how to accomplish the goal of managing our climate, what it will take, and when it needs to be done. Such a management process has to be dynamic, making it more complex and less didactic, requiring changes in strategy to achieve a longer-term goal as our knowledge advances.
Global Climate Change and Human Life is a comprehensive and cohesive look at the emerging field of global change science. Using models that take the theoretical or conceptual understanding and translate them into mathematical forms, the book lays out a holistic view of the science that develops and teaches the main principles, concepts and conclusions. In the end, readers will be empowered to use science and the scientific method to decide how important and timely climate change is as a social issue and which solutions can succeed.
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Global Climate Change and Human Life
M. A. K. Khalil
Portland State University, Portland, Oregon, USA
This edition first published 2022
© 2022 John Wiley & Sons Ltd
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Set in 9.5/12.5pt STIXTwoText by Integra Software Services Pvt. Ltd, Pondicherry, India
Contents
Cover
Title page
Copyright
Preface
About the Companion Website
1 Introduction
1.1 What Is Global Change Science?
1.2 Current Global Change
1.3 Raising Fundamental Questions
Endnotes
2 The Framework
2.1 The System
2.2 Scales of Action
2.3 What Determines Climate?
2.4 The Benchmark Average Climate
2.5 Irreducible Uncertainties
2.6 The Plan
Review of the Main Points
3 Atmospheric Composition
3.1 Trace Gases and Their Roles in Climate and the Environment
3.2 Quantifying the Atmospheric Composition
Review of the Main Points
Endnotes
4 Mass Balance Theory and Small Models
4.1 The Components
4.2 Global
4.3 Hemispherical and Horizontal
4.4 Vertical
Review of the Main Points
Endnotes
5 Transport Processes
5.1 Vertical Transport and Convection
5.2 Horizontal Motion and the General Circulation
5.3 Turbulent Transport
5.4 Quantifying Transport Processes
Review of the Main Points
Endnotes
6 Mechanisms of Sources and Sinks
6.1 Reservoirs and Source-Sink Relationships
6.2 Atmospheric Chemistry
6.3 Global Environmental Applications
6.4 Cross-Media Transport: Oceans, Soils, and Biota
Review of the Main Points
Endnotes
7 Balance of Climate Gases and Aerosols
7.1 Anthropogenic vs Natural Components
7.2 Greenhouse Gases
7.3 Aerosols
Review of the Main Points
Endnotes
8 The Science of Climate
8.1 Solar Radiation
8.2 Albedo
8.3 Radiative Transfer
8.4 Heat Storage and Balance
8.5 Precipitation
Review of the Main Points
Endnotes
9 Instructive Climate Models
9.1 Base Temperature Model – Lessons, Flaws, and Resolution
9.2 Radiative Forcing and Climate Sensitivity
9.3 Practical Relationships between Greenhouse Gases and Surface Warming
9.4 Role of the Oceans
9.5 Role of Clouds
9.6 Horizontal Transport of Heat
Review of the Main Points
Endnotes
10 Climate Feedbacks
10.1 How They Work
10.2 Feedbacks Classified and Delineated
10.3 Physical Feedbacks
10.4 Role of the Living World
Review of the Main Points
Endnotes
11 Match of Climate Change Observed and Modeled
11.1 What Is Global Warming?
11.2 Causes of Observed Warming
11.3 Differential Effects of Climate Change
Review of the Main Points
Endnotes
12 Population, Affluence, and Global Change
12.1 Basic Relationships
12.2 Societal Factors in Climate Change
12.3 Population Growth and Resources
12.4 Vulnerability Theory
Review of the Main Points
Endnotes
13 Impacts of Climate Change on Human Life
13.1 Impacts Classified
13.2 Health
13.3 Habitability
Review of the Main Points
Endnotes
14 Climate Management
14.1 Tragedy of the Commons
14.2 Compounding Forces of Resistance
14.3 Mechanisms for Managing the Climate
14.4 Geo-engineering
14.5 Trading Gases: The Global Warming Potential
Review of the Main Points
Endnotes
15 Possible Futures
15.1 Projections
15.2 The Metaphysics of Climate Change
Endnote
List of Symbols Used
Index
End User License Agreement
List of Figures
Chapter 1
Figure 1.1 Observations of the changing...
Chapter 2
Figure 2.1 A minimalistic view...
Figure 2.2 Space and time...
Figure 2.3 Time scales of air...
Figure 2.4 Factors controlling...
Figure 2.5 Defining variables...
Figure 2.6 State of the Climate...
Figure 2.7 The process of global...
Figure 2.8 The plan and logic...
Chapter 3
Figure 3.1 Which gases do what...
Figure 3.2 How the pressure...
Chapter 4
Figure 4.1 Components of the global...
Figure 4.2 The meaning of lifetime...
Figure 4.3 Buildup and decline...
Figure 4.4 Change of global effective...
Chapter 5
Figure 5.1 Convection and the vertical...
Figure 5.2 Rising air parcels...
Figure 5.3 Possible vertical temperature...
Figure 5.4 The general circulation...
Figure 5.5 The Coriolis force...
Figure 5.6 Turbulence and mixing...
Figure 5.7 Illustration of turbulent...
Figure 5.8 Turbulence and gradient...
Figure 5.9 Transport barriers and...
Chapter 6
Figure 6.1 Chemical sinks in the atmosphere...
Figure 6.2 Photons, particles, and molecules...
Figure 6.3 Electromagnetic radiation spectrum...
Figure 6.4 The precursors of the hydroxyl...
Figure 6.5 Tropospheric hydroxyl concentrations...
Figure 6.6 The stratospheric ozone layer...
Figure 6.7 Illustration of cross-media...
Chapter 7
Figure 7.1 The concentrations and trends...
Figure 7.2 The global balance of water...
Figure 7.3 A view of the carbon cycle...
Figure 7.4 The global sources...
Figure 7.5 The nitrogen balance and...
Figure 7.6 Aerosols and climate...
Figure 7.7 Atmospheric aerosols...
Chapter 8
Figure 8.1 The solar constant...
Figure 8.2 Interception of solar...
Figure 8.3 Solar spectrum...
Figure 8.4 Solar radiation by...
Figure 8.5 Albedos of features...
Figure 8.6 Absorption of radiation...
Figure 8.7 Absorption mechanics of infrared...
Figure 8.8 The absorption efficiency...
Figure 8.9 Absorption of solar...
Figure 8.10 he calculated contribution...
Figure 8.11 The atmosphere sends more...
Figure 8.12 Energy balance of the earth...
Chapter 9
Figure 9.1 The simplest climate model...
Figure 9.2 Energy absorption scenarios...
Figure 9.3 Conduction at the interface...
Figure 9.4 Radiative forcing changes...
Figure 9.5 Ocean thermal inertia...
Figure 9.6 Horizontal transport...
Chapter 10
Figure 10.1 The course of positive...
Figure 10.2 Climate feedbacks affecting...
Figure 10.3 Feedback factors and gains...
Figure 10.4 Temperature and the idealized...
Figure 10.5 Daisy world temperature...
Chapter 11
Figure 11.1 Annual average temperature...
Figure 11.2 Trends of the global temperature...
Figure 11.3 Causes of global warming...
Figure 11.4 Match between observations...
Figure 11.5 Energy balance in the stratosphere...
Figure 11.6 Observed stratospheric cooling...
Chapter 12
Figure 12.1 Markers of affluence...
Figure 12.2 Cumulative CO2 emissions...
Figure 12.3 Population Growth Functions...
Chapter 13
Figure 13.1 Impacts of climate change...
Figure 13.2 Win-lose diagram of climate...
Figure 13.3 The distribution of temperatures...
Figure 13.4 How extreme events increase...
Figure 13.5 How extreme hot days increase...
Figure 13.6 Population density and climate...
Chapter 14
Figure 14.1 Tragedy of the commons...
Figure 14.2 Mechanisms of climate...
Figure 14.3 GWP and radiative forcing...
List of Tables
Chapter 3
Table 3.1 Atmospheric composition...
Chapter 6
Table 6.1 Mechanisms of Sources...
Chapter 12
Table 12.1 Outcomes of the Interaction...
Chapter 14
Table 14.1 A Dilemma of Climate Change.
Guide
Cover
Title page
Copyright
Table of Contents
Preface
About the Companion Website
Begin Reading
List of Symbols Used
Index
End User License Agreement
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Preface
At the start, I intended to write this book for all college students and practically everyone else with an interest in the global environment. My goal became increasingly difficult to attain as I progressed. I still think it will serve this community, but not everything will be understood by everyone. In studying climate change, and environmental science in general, there are many simultaneous and credible influences. Which are important and which can be ignored require the ability to associate numbers with the causes of each phenomenon. To provide that ability without resorting to complex mathematics was a daunting task, but I have managed to do so with the use of only basic algebra. Results from more advanced mathematics have been relegated to simple formulas without proofs, because these are not the debatable aspects of climate science, but whether they apply under the circumstances we are studying may be. So, my readers should be comfortable in proceeding to learn from this book, regardless of their majors, or academic backgrounds. I believe it will benefit the middle years’ college students the most, and the exercises at the ends of the chapters are designed for them to attain a deeper understanding of global change science within a formal course. Resources are available from the publisher for university-level instructors that will considerably reduce the work needed to get a course up and running in any department.
The book itself takes a holistic view of global change science in which the earth’s climate is a focal point. It takes established ideas from the basic sciences such as physics, chemistry, biology, and several social sciences and fuses them into a coherent framework using many new ideas and concepts that are needed to make the connections. These connections and ideas, and their consequences, are expected to evolve over time, as the science develops to serve the societal needs for managing the global environment and especially the climate.
Numerous colleagues, friends, students, and family members have contributed to the development of this book over many years. Major contributions came from my hundreds of students who were asked to write an essay at the end of the course titled “The single most amazing thing I learned from this course.” It made me understand better what mattered to those who wanted to learn this subject. Colleagues who read the text and provided suggestions are: Drs. R.M. Mackay, P. Loikith, A. Rice, and C. Butenhoff. I had conversations about the contents of the book over many years with: Rei Rasmussen, Kathayoon Khalil, and Ed Immergut (at J.Wiley & Sons). Finally, my parents, wife, and children contributed in intangible, but crucial, ways just by being there.
M.A.K. Khalil, ProfessorPortland, Oregon, USASeptember 2021.
About the Companion Website
This book is accompanied by a companion website for Instructors:
www.wiley.com/go/khalil/Globalclimatechange
This website includes:
Solutions to the Exercises in the book
A downloadable MCQ test bank
Figures from the book in Power
PointGeneral Tools and Course Elements
Term Paper Project: A Guide for Students from the Instructor
1 Introduction
1.1 What Is Global Change Science?
In our time, the population has become large enough to cause perceptible environmental changes all over the world. With it, a science of global change has emerged, mostly as a practical matter to understand and manage the earth’s habitability and create a sustainable environment for some time to come. This goal amounts to balancing the benefits of technological and societal advances with the undesirable potential side effects. Concerns started with the depletion of the stratospheric ozone layer and its possible adverse consequences on human health. It has, in recent decades, shifted to climate change driven by an observed ongoing global warming.
Global change, including climate, is a derivative, interdisciplinary science. It deals with how the earth’s environment and particularly its climate interact with human life over periods of decades. The system it represents and describes is the earth’s habitable surface environment, which is determined by the characteristics of the atmosphere, oceans, and the land, and the interactions between them. It uses long known and verified principles of the sciences. Still, of all the issues surrounding the scientific inquiry into our world, global change science is the most obscure, mostly because it is not just about physics, or chemistry, or biology, or sociology nor any other “ology”; it respects no such boundaries because it is about the real world, which functions according to all of them acting simultaneously.
There are two complementary aspects to consider. The first is traditional climatology that has developed over the last century. It deals with how climate is manifested in different parts of the world and its repeating annual cycles; it includes the science and models developed for weather forecasting. An enormous amount of observational data have been taken and combined with theories to achieve a solid understanding of the climate we experience, although climate science, like all others, will continue to evolve forever. The second aspect deals with climate change that can arise if one or another of the fundamental variables that control climate is altered. This takes us beyond the realm of climatology into new domains of the earth’s environment for which there is less observational data and little human experience. Phenomena that are dormant in a stable climate suddenly come into play in a changing one, and these are even more complex to unravel than the natural stable climate. It is this second aspect that will be our interest. We will see how global change science goes beyond the comfortable understanding of climate and into the realms of a new science.
We will spend a considerable amount of time to understand the current climate and environment because it is the baseline from which future change will evolve, altered by natural and human forces. We will focus on expected changes over time scales of decades to perhaps a century or so. These are the periods that overlap with human life spans, and it is the times over which societies can cause global climate change and over which they may be able to manage it.
1.2 Current Global Change
We start by looking at the global observations which show that the earth is getting warmer (Figure 1.1a.). As this warming progresses, it will have consequential impacts on parts of the environment that affect human life in various ways, some of which will be undesirable. In this figure we see the readily observed direct environmental consequences such as increasing sea levels and decreasing high-latitude snow cover.
Figure 1.1 Observations of the changing global environment. The increase of global temperature, sea-level rise, and ice decline are shown (Endnote 1.1).
1.3 Raising Fundamental Questions
From the discussion so far, the following fundamental questions may be posed: Why are these global changes occurring? How will they affect our lives? If we find the effects undesirable, what should we do? We will create a path to answering these questions. For the first question we will need an understanding of how the composition of the atmosphere determines the climate; in turn, what determines atmospheric composition and then, how it can be altered. This is the best-known part of the science. To answer the second question, we will study how climate affects the environmental factors that are important to human life, such as crops, rain, and extreme weather events. The impact of the consequences is not uniformly global; it is often detrimental for some regions and negligible or beneficial for others, thus adding further complexity to finding unequivocal answers. The last question has no clear answers, and perhaps never will, but what we learn here will show how to accomplish the goal of managing climate, what it will take, and when it needs to be done. Such a management process has to be dynamic, making it more complex and less didactic, requiring changes in strategy to achieve a longer-term goal as our knowledge advances.
It is apparent that global change is expected to have concerning consequences for human life, but that will depend entirely on how big the stated impacts are going to be. It is not enough to merely say what climate change might do. It may occur, but may be so small that there is no cause for concern. Without the ability to understand the numbers associated with these changes, people, including you and me, have no clear way to accept or reject a plan for climate management or even a need for it. Building the numbers from the underlying science that is readily understandable is a major goal of this book. This inevitably requires models which take the theoretical or conceptual understanding and translate them into mathematical forms with the primary goal to calculate the values of variables that interest or concern us. The models we will use in this book are the simplest we can construct to serve our goals and represent global change science. They will lay out a holistic view of the science that develops and teaches the main principles, concepts, and conclusions. In the end, readers will be empowered to use science and the scientific method to decide how important and timely climate change is as a social issue and which solutions can succeed. But behind this practicality, a greater goal is to satisfy our curiosity about how the earth’s climate works and our role in it – indeed, it is to understand the conjoined character of life on earth and its environment (Endnote 1.2).
Endnotes4
Endnote 1.1
Figure 1.1
is taken from IPCC’s AR4. The IPCC is “The Intergovernmental Panel on Climate Change”; it is a United Nations organization charged with evaluating ongoing global climate change. They issue periodic consensus reports that review, synthesize, and document the published scientific literature on global change science and in recent years have stimulated research to facilitate such an analysis. The synthesis of research results from these reports is used in this book to illustrate aspects of global change, as needed. The reports are: FAR (
F
irst
A
ssessment
R
eport), 1990; SAR (
S
econd), 1995; TAR (
T
hird), 2001; AR4 (
F
orth), 2001, AR5 (
F
ifth), 2013 and AR6 (
S
ixth), 2021; all published by the Cambridge University Press, Cambridge, UK.
Endnote 1.2
It is useful to state the meaning of some terms that are commonly used in this book, and in everyday public discourse.
Global warming
is the increase of the average temperature of the earth that persists over time scales of a decade or more. It is narrower than
climate change
, which can include changes of rainfall, winds, humidity, and perhaps other attributes of climate. They may change because of global warming, or from some other cause.
Global change
is wider still. In our context, it includes climate change, environmental changes that can come from it, such as sea-level rise, and its effects on human life as well as the global societal responses to manage its adverse effects. The term “global change” may be used in other contexts that are not related to climate. “Greenhouse gases” is another commonly used term. It expresses an attribute of atmospheric constituents that have the special property, that they trap the earth’s heat and warm the earth’s surface which is stated as
the greenhouse effect
. These are the only gases that can cause global warming if increased by human activities or natural causes. Many other terms will be used in this book that relate to climate and global change; these will be defined and elaborated as we go along.
3 Atmospheric Composition
3.1 Trace Gases and Their Roles in Climate and the Environment
Average atmospheric composition at the earth’s surface is shown in Table 3.1. Many of the longer-lived gases are present at the same percentages in much of the troposphere. The table is a little different from what appears almost everywhere else because water vapor has been included as an integral part of atmospheric composition at 0.5%. It should be noted that water vapor consists of separated molecules that are present in air which also contains condensed water as clouds, mists, and fog; and some is in solid form as ice crystals. Water vapor is invisible, although we feel it as humidity. Traditionally, dry air composition is tabulated and water is not reported because it is highly variable in both space and time; at some locations or times it may be a few parts per million and at other places it could be up to 5%, whereas dry air is thought to have the same composition everywhere. This is so for the major gases such as nitrogen, oxygen, and the noble gases, but trace gases generally vary by latitude and season. Water vapor, as we will see later, is the most important greenhouse gas and also contributes to global warming significantly. In a discussion about climate science, it is reasonable to include it directly in atmospheric composition to emphasize its importance from the very beginning, along with the less variable but also less concentrated greenhouse gases.
Table 3.1 Atmospheric composition in recent millennia.
Atmospheric composition: Major, greenhouse and noble gases.
(
1
)
Gas
Volume(%)
(
2
)
N
2
78.08
O
2
20.95
Ar
0.93
H
2
O
0.5
CO
2
0.040
Ne
0.0018
He
0.00052
CH
4
0.00018
Kr
0.00011
H
2
0.000055
N
2
O
0.000033
Xe
0.0000090
O
3
0.0000040
HCFCs
0.00000003
CCI
3
F
0.00000002
CCI
4
0.000000013
PFCs
0.000000008
SF
6
0.0000000010
Notes
1) There are many more gases in the earth’s atmosphere, but their roles in climate and global change are very small.
2) The total adds up to about 100.5% because of the inclusion of water vapour. The remaining concentrations are for dry air as traditionally reported.
The picture we see is that 99% of the dry air is nitrogen (78%) and oxygen (21%) and yet they have almost no direct influence on the greenhouse effect or global climate change! Their role in climate is to be the winds, hold heat, carry water from the oceans to the land, and to transport greenhouse gases and pollutants away from the sources and spread them over the whole world. Nitrogen and oxygen are the only atmospheric gases whose existence we feel regularly, including our need to breathe. That leaves only 1% of the atmosphere, and most of it is made up of argon and the other noble gases that have virtually no role in the environment as it affects living things. We are left with less than 0.05% of the dry atmosphere that includes greenhouse gases such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O); and the ozone-depleting compounds such as the chlorofluorocarbons (CCl3F, CCl2F2). This small fraction, made up of myriad trace gases, have influences on the environment that are disproportional to their meager concentrations. Man-made gases implicated in the destruction of the ozone layer, even when taken together, never reached one molecule in a million of air. This leads to the principle that living things gain the capacity to perceptibly alter the environment and the climate or even to control it, because even small emissions of the trace gases can have hugely amplified impacts. This may be so on other planets as well, making it more probable that life can take hold in a wide spectrum of physical environments because of rare gases in the atmosphere.
There are a few more noteworthy characteristics that appear in Table 3.1. One is that most of the earth’s atmosphere consists of very light gases of two or three atoms and the single-atom noble gases. Methane is the largest-sized gas of natural origins affecting climate. Many of the five to seven atom gases are man-made halocarbons with strongly bonded atoms. More complex organic compounds are produced in abundance by biological processes, but either do not evaporate into the atmosphere, or are so chemically reactive that they do not last long once they get there. Another matter is that once we go below about 0.000001% concentration there are many gases that are known to exist in the global atmosphere, perhaps thousands of them. Despite the amplified effects of some of them, they are of marginal environmental significance because of their extremely low concentrations. Table 3.1 lists some of these extremely rare gases because they are targets of major international agreements such as the Montreal Protocol, to prevent the depletion of the ozone layer, and the Kyoto Protocol to manage the climate.
Readers may find an analogy about the rarity of trace greenhouse gases both amusing and illuminating. Let’s say we represent the different gases in the atmosphere by the color of M&Ms® in a container. The brown ones are common so they can be nitrogen and red ones can be oxygen. Let’s make carbon dioxide blue, methane yellow, nitrous oxide purple, and carbon tetrafluoride the elusive pink one. We ask: how large a box would we need to find an M&M of the color that represents one of the trace gases. After much testing and consuming of M&Ms, it turned out that the volume of M&M is about 0.636 cm3 and they fill up about 68% of the space, so each occupies 0.9 cm3 of the box. To find one blue M&M representing carbon dioxide you will need a cubic box about 5 inches (13 cm) on the side. The rest will be brown or red assuming that the colors are evenly mixed. For methane, you will need a cubic box about 30 inches (80 cm) – that is already fairly large. Nitrous oxide’s purple M&M will be one in a box that is 5 feet (143 cm) on the side; and to find a pink one, you will need a box the size of a very large warehouse 1/4 of a mile × 1/4 of a mile on the sides and 10 feet high! It is a marvel of nature that gases present in such small quantities, and many generated by living things, can have such a major effect on the earth’s climate.
To get our bearings, it is useful to review which gases do what, so as to motivate a further study of these particular gases and how they can affect the climate, ozone layer, or other aspects of our environment (Figure 3.1). For climate, the gases that cause the greenhouse effect and global warming, in order of their importance are H2O, CO2, CH4, N2O, and O3. Of lesser importance, because of very low concentrations, are many technological gases including chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs) and sulfur hexafluoride (SF6). There are sulfur gases such as sulfur dioxide (SO2), carbonyl sulfide (OCS), and dimethylsulfide (DMS) that turn into light-scattering aerosols and, along with other sources of particles, can cool the earth’s surface. Their effects from man-made emissions are overwhelmed in most places by the greenhouse gases mentioned earlier. For the depletion of the ozone layer the two most abundant man-made chlorofluorocarbons (CCl3F and CCl2F2, also known as CFC-11 and CFC-12) are the most significant followed by many other rarer chlorine and bromine containing gases, most of which are entirely from human activities. The natural ozone layer chemistry is driven by sunlight, oxygen (O2), and destructive molecular fragments from the breakup of nitrogen, hydroxyl, and halogen-containing gases (N2O, H2O, CH3
