Challenge of Global Warming

by Dean E. Natural Resources Defense Council, Dean E. Abrahamson (Editor), Timothy Wirth (Foreword by)

Overview

Challenge of Global Warming examines the causes and effects of global climate change.

Product Details

ISBN-13:	9781597269254
Publisher:	Island Press
Publication date:	04/22/2013
Sold by:	Barnes & Noble
Format:	eBook
Pages:	376
File size:	17 MB
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About the Author

Dean Edwin Abrahamson is professor of public affairs at the University of Minnesota's Hubert H. Humphrey Institute of Public Affairs, co-chair of the university's Council on Environmental Quality, an adjunct professor at the University of Iceland, and a member of the board of the Natural Resources Defense Council. He has degrees in physics, medicine, and biology and has held a variety of jobs in industry, government, and academia. Since the late 1960s his primary work has been environmental and public health implications of energy policies, and for the last several years it has focused on the policy implications of the greenhouse effect.

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The Challenge of Global Warming

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By Dean Edwin Abrahamson

ISLAND PRESS

Copyright © 1989 Island Press
All rights reserved.
ISBN: 978-1-59726-925-4

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CHAPTER 1

GLOBAL WARMING: THE ISSUE, IMPACTS, RESPONSES

Dean Edwin Abrahamson

THE ISSUE

Humanity is conducting an unintended, uncontrolled, globally pervasive experiment whose ultimate consequences could be second only to nuclear war. The Earth's atmosphere is being changed at an unprecedented rate by pollutants resulting from human activities, inefficient and wasteful fossil fuel use and the effects of rapid population growth in many regions. These changes are already having harmful consequences over many parts of the globe.

—Toronto Conference statement, June 1988

This analogy between the consequences of nuclear war and atmospheric pollution was made not by idealistic, scientifically innocent environmentalists, but by the more than 300 policymakers and scientists from 46 countries, United Nations organizations, other international bodies, and nongovernmental organizations who attended a major international conference sponsored by the government of Canada. The Toronto Conference statement, included in full in Chapter 3, illustrates that it is now clearly within our power not only to alter the planet beyond comprehension within a few hours by using nuclear weapons, but also within a few decades by destroying the earth's life-support systems and radically changing climate by contamination of the air and water with the residuals of production.

Global climate is changing because of the buildup in the atmosphere of carbon dioxide (CO2), methane, nitrous oxide (N2O), the CFCs (powerful greenhouse gases as well as destroyers of stratospheric ozone), and other greenhouse gases produced by fossil fuel burning, by deforestation (discussed in detail in Chapter 5), and by producing food for the rapidly increasing global population.

The consequences of the global heating which would result if present release rates of the major greenhouse gases are maintained for only a few more decades would be catastrophic if our present scientific understanding is even approximately correct, and the resulting climatic change would be irreversible. (See the report of the 1987 Villach-Bellagio conferences in Chapter 7.) It is now known that a warming of several degrees, greater than previously experienced in human history, could occur within the next few decades—a time which is short compared with the lifespan of a tree or a man. Major changes will result in ecological, economic, and social systems as all are in delicate balance with their environments which in turn are dependent on climate. No one can now describe the precise nature of these changes—in part because of the technical demands of climate modeling and in part because of the impossibility of predicting the choices which will be made within the next 50 or so years—but change there will be. Although the crystal ball is too cloudy to reveal the details, the general course of climatic change is well understood (see Chapter 8).

Studies of past climate changes can tell us something about the response of forests. As the last ice age retreated, the earth warmed, slowly, for several thousand years. This change completely rearranged the face of the United States. Tree species that grew in Ohio and Michigan migrated far into Canada, and other tree species from the Deep South moved north into Ohio and Michigan.

If we allow emissions of CO2and the other greenhouse gases to continue unabated, the earth will warm five to ten times faster than it did during the retreat of the last ice age. Many trees cannot migrate much faster than they did as the earth slowly warmed following the last ice age. By the time a tree matures enough to produce seeds, the climate will be unfavorable for those seeds to take hold and produce the next generation. We thus could be heading toward a country almost devoid of young trees, a country given over to shrubs that tolerate a wide range of conditions—a sumac world.

As go the forests, so go the other species, animal and plant, supported by them. As Robert L. Peters suggests in Chapter 6, the most likely outcome is widespread extinction of species. The U.S. National Research Council has concluded: "It seems likely that the impacts of climatic change will fall most severely on immovable, and therefore inflexible, elements of both natural and man-made infrastructures.... National parks and biosphere reserves are usually established to preserve some asset of unique physical or biological importance, often depend on climatic factors, and cannot be easily removed or replaced."

Each 1°C of global warming will shift temperature zones by about 100 miles. A continuation of present trends in the emission of CO2 and the other greenhouse gases is expected to result in additional global heating of at least 2°C by the year 2030. Were this to happen, the climate upon which, for example, Yellowstone Park's ecosystem depends will have moved—the place called Yellowstone will be occupied by a different ecosystem. All the effort which has gone into the park from its creation through fighting the 1988 fire will have been in vain if global warming is not limited. Other parks, refuges, and wilderness will also be affected by warming, by changes in water balance, or by saltwater intrusion.

Continued global heating will also increase sea level by 1 to possibly 3 meters within the next hundred years (detailed in Chapter 12). This sea-level rise would be sufficient to inundate most salt marshes and coastal wetlands, change the character of the Everglades, push barrier islands further toward the present coast, and contaminate coastal aquifers. Reduced summer soil moisture would result in the loss of freshwater wetlands, reduced stream flows, and further lowering of aquifers. The consequences would include loss of wetlands habitat, reduced water quality, and increased concentrations of toxic wastes.

Coping with global heating and global climatic change may be the ultimate environmental challenge. If we fail to reduce emissions of the greenhouse gases, the climate change expected within the next few decades will be sufficient to jeopardize resources which much of the present environmental legislation is designed to protect.

The Brundtland Report details the challenge of making room for a world population of 8 to 14 billion people within the next century and a severalfold increase in world economic activity. A world with a doubled or tripled human population, with a severalfold increase in consumption, and with greenhouse gases, industrial pollutants, and other assaults on the environment proportional to those of today is not only virtually unimaginable, but impossible. If societies attempt a severalfold increase in economic activity described in the Brundtland Report using the present means of production, increasing emissions of greenhouse gases will have consequences similar to those of nuclear war. We have no alternative but to devise means of production which can provide the necessary goods and services to a growing population without causing irreversible biotic impoverishment.

THE GREENHOUSE EFFECT

Global warming has reached a level such that we can ascribe with a high degree of confidence a cause and effect relationship between the greenhouse effect and the observed warming.

—James Hansen, NASA climatologist, 1988

The greenhouse effect results from the buildup in the atmosphere of gases which absorb heat (long-wavelength infrared radiation), a topic considered in detail by Gordon MacDonald in Chapter 9. To maintain a constant average temperature, the earth must radiate heat to space. Greenhouse gases like CO2and methane absorb a part of this heat energy and reradiate it back to the surface of the planet, thereby effectively trapping it in the lower atmosphere. This process raises the temperature of the atmosphere near the earth, which in turn raises sea level, increases evaporation and precipitation to affect global cloud cover, and thereby alters the distribution of climate across the surface of the planet. An increase in average global temperature of 0.7°C has already been measured, and present rates of emission of greenhouse gases are committing the earth to an additional warming of about 0.3°C per decade.

It is because they trap heat like glass in a greenhouse that these gases received their name—the greenhouse gases. They are vitally important for life. Venus, with an atmosphere rich in CO2, has a greenhouse effect of between 400 and 500°C, and Mars, with its thin atmosphere, only a few degrees. Earth has a natural greenhouse effect due to the presence of CO2 and water vapor. If Earth's atmosphere did not contain these gases, its temperature would be 33°C lower. The natural level of these gases make life as we know it possible.

Increasing them beyond today's level will cause the climate to diverge markedly from its present state. Climatic zones shift by about 100 miles for each 1°C of global warming. Sea level will rise all over the earth. Major weather patterns—for example, the tropical monsoons and jet streams—are altered. A warming of about 4°C, to which we may be committed in less than 50 years, would result in an ice-free Arctic Ocean which will not only devastate arctic ecosystems but will further change climate and weather. A warming of this extent could also begin an irreversible disintegration of the West Antarctic ice sheets which would result, within a few hundred years, in a further rise in sea level by at least 6 meters.

ABOUT THE GREENHOUSE GASES

Carbon dioxide, the single most important greenhouse gas, accounts for about half of the warming that has been experienced as a result of past emissions and also for half of the projected future warming. The present concentration is now about 350 parts per million (ppm) and is increasing about 0.4% (1.5 ppm) per year, retaining an additional 3 billion tons (10 tons or GT) of carbon per year. For a very long period of time before the industrial age, the atmospheric concentration was essentially constant. Beginning about 1850, however, the CO2 level began to rise, due in large part to the industrial burning of first coal and then oil and natural gas. The atmospheric CO2 level in 1850 was probably about 270 ppm; thus it has already increased by about 30%. Human activities are now causing at least 7 billion tons of carbon, as carbon dioxide, to be released into the atmosphere. Fossil fuel use releases about 6 billion tons per year to the atmosphere. In addition, the clearing and burning of forests causes the pool of carbon which has been tied up in trees to be released. Deforestation is in part the result of population expansion in the tropics and the use of land for agriculture and wood for energy. The desire of developed countries for inexpensive meat and forest products is another major contributor to deforestation. Each year a land area the size of Belgium is deforested, resulting in the transfer from forests to the atmosphere of between 1 and 3 billion tons of carbon per year, as detailed by George M. Woodwell in Chapter 5.

If present trends in the release of CO2to the atmosphere continue, the preindustrial level of CO2will increase another 30% in 50 years, and then double about the year 2100. In principle, there are no obvious physical constraints to limit this rise. The remaining amounts of oil and gas are quite small, but the amount of coal that is subject to exploitation is essentially unlimited. Economics and policy on emission of greenhouse gases will govern how rapidly CO2builds up before either humankind or nature acts to stabilize the atmospheric burden of greenhouse gases.

In addition to CO2, another 20 or so greenhouse gases have been identified (detailed by Peter Ciborowski in Chapter 14). At present the most important are methane (CH4), the chlorofluorocarbons CFC-11 and CFC-12, nitrous oxide (N2O), and ozone (O3) in the lower atmosphere (see Chapter 15). Taken together, these other greenhouse gases are responsible for at least as much global warming as is CO2, and perhaps more. At present methane is the most important of these gases, followed closely by CFC-12.

Methane is produced in flooded fields and waterlogged soils, in rice paddies, in the guts of cattle and other fauna, in landfills, and in coal seams. It is also released as a result of forest clearing, venting in association with oil production, and leakage from natural gas pipelines. Atmospheric methane concentration is now increasing at about 1% per year (see Chapter 17). CFC-12 is primarily used as the working fluid in refrigerators and air conditioners. CFC-11 is used mainly in plastic urethane foams. The CFCs in general are used in spray cans, forming plastic foams, and as solvents. (See Chapter 20.) Nitrous oxide is released as a result of coal combustion and in the breakdown of agricultural fertilizers. Tropospheric ozone is photochemically produced in the atmosphere as a result of the release of methane, carbon monoxide, and other hydrocarbons, due largely to emissions from fossil fuel burning.

Atmospheric concentrations of the principal non-CO2 greenhouse gases are increasing from between 0.3% per year in the case of nitrous oxide to 5% per year in the case of CFC-11 and CFC-12. (See Chapter 16.) Tropospheric methane and ozone are increasing in concentration about 1% annually. All these rates of increase, if continued or only marginally reduced, will result in climatically significant atmospheric accumulations of these gases.

CLIMATE SENSITIVITY

As CO2and the other greenhouse gases accumulate in the atmosphere, the temperature near the surface of the earth will rise. Climate modelers and other atmospheric scientists have performed elaborate calculations to determine how much it might warm (see Chapter 8). The estimates are usually expressed in degrees centigrade of mean global temperature change—the rise of surface temperature averaged across the globe. They are typically given for a standard experiment—a doubling of the amount of atmospheric CO2, which is a measure of how sensitive the climate is to the greenhouse gases. The best of the present climate models show that if atmospheric CO2were to double, the average global temperature would rise by between 3.5 and 4.5°C. By way of comparison, the typical natural variation of mean global temperature over periods of 100 to 200 years has been at most 0.5 to 1°C—smaller than the expected rise in mean global temperature for doubled CO2by at least a factor of 4. The warming would be two or three times the global mean in high latitudes and less than the global mean near the equator.

THE OCEAN THERMAL DELAY

It will require a much longer period of time to warm the oceans than it will to warm the atmosphere. Thus there is a delay of at least a decade and perhaps half a century between the time that greenhouse gases are added to the atmosphere and the time that the full warming effect of these cases can be measured. It is thus necessary to distinguish between the eventual global heating which will result from any given amount of greenhouse gases added to the atmosphere—the equilibrium warming—and the heating which is experienced at any point in time—the transient warming.

It is essential to note that the greater the warming from the greenhouse gases, the longer the ocean thermal delay. If there is a global warming of only 1.5°C for doubled atmospheric CO2, the delay may be only about 15 years; but if doubled CO2results in 4°C warming, the delay may be from 50 to 100 years. As a consequence, the global warming which has been observed to date is consistent with either a low climate sensitivity to increased greenhouse gases, accompanied by a short ocean thermal delay, or with a high climate sensitivity which would be accompanied by a long ocean thermal delay.

TODAY'S GLOBAL WARMING

Measurements have shown that the earth's surface temperature has increased by between 0.5 and 0.7°C since 1860. Current climatic models show that a transient warming of between 0.5 and 1.0°C from greenhouse gases added to the atmosphere during the last century should have occurred. If we consider the equilibrium warming that should have resulted from these emissions, however, the situation is different, as past emissions should have committed the planet to an equilibrium surface warming of between 1 and 2.4°C. The difference between the calculated equilibrium, or committed warming, and the observed warming—0.5 to 1.7°C—is the unrealized warming from past emissions. This warming will be expressed over the next few decades regardless of what we do about future releases of the greenhouse gases.

At the present rate of emissions of the greenhouse gases, we are committing the earth to an additional warming of at least 0.15°C and perhaps as much as 0.5°C each decade. If the present rates of growth in emissions were to continue, by the year 2030 we would be committed to a mean global warming of at least 3°C and perhaps as much as 5°C. (See the 1985 Villach Conference statement in Chapter 4.) Over a century this figure could reach 5 to 10°C. This would change the earth, in less than a single human lifetime, to a climatic regime not experienced for millions of years.

(Continues...)

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Excerpted from The Challenge of Global Warming by Dean Edwin Abrahamson. Copyright © 1989 Island Press. Excerpted by permission of ISLAND PRESS.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

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Table of Contents

Preface

Introduction - Senator Timothy E. Wirth



PART I. The Challenge of Global Warming

Chapter 1. Global Warming: The Issue, Impacts, Responses

Chapter 2. The Greenhouse Effect: Impacts on Current Global Temperature and Regional Heat Waves

Chapter 3. The Changing Atmosphere: Implications for Global Security

Chapter 4. The Scientific Consensus

 

PART II. Global Warming: Biotic Systems

Chapter 5. Biotic Causes and Effects of the Disruption of the Global Carbon Cycle

Chapter 6. Effects of Global Warming on Biological Diversity

Chapter 7. Developing Policies for Responding to Climate Change



PART III. Global Warming: Physical Impacts

Chapter 8. Greenhouse Effects and Impacts on Physical Systems

Chapter 9. Scientific Basis for the Greenhouse Effect

Chapter 10. Changes in Soil Moisture

Chapter 11. Effects of Climatic Change on Water Supplies in the Western United States

Chapter 12. The Causes and Effects of Sea Level Rise

Chapter 13. Greenhouse Surprises



PART IV. The Greenhouse Gases

Chapter 14. Sources, Sinks, Trends, and Opportunities

Chapter 15. Global Warming, Acid Rain, and Ozone Depletion

Chapter 16. Observed Increases in Greenhouse Gases and Predicted Climatic Changes

Chapter 17. Methane, CFCs, and Other Greenhouse Gases

 

PART V. Policy Responses

Chapter 18. The Dangers from Climate Warming: A Public Awakening

Chapter 19. One Last Chance for a National Energy Policy

Chapter 20. An Analysis of the Montreal Protocol on Substances that Deplete the Ozone Layer

Chapter 21. Near-term Congressional Options for Responding to Global Climate Change



For Further Reading

For Further Information

Index