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Orrin H. Pilkey is James B. Duke Professor Emeritus of Geology at the Nicholas School of the Environment at Duke University, and Founder and Director Emeritus of the Program for the Study of Developed Shorelines, based at Western Carolina University. Pilkey has written and edited many books, including, most recently, (with Rob Young) The Rising Sea and (with Linda Pilkey-Jarvis) Useless Arithmetic, an indictment of mathematical models used to predict environmental change. He is the author or co-author of many books in the Living with the Shore book series that he co-edited for Duke University Press. Pilkey is the recipient of numerous honors, including the Francis Shepard Medal for excellence in Marine Geology, the Priestley Award for distinguished contributions to environmental science, a Lifetime Achievement Award from the North Carolina Coastal Federation, and the Outstanding Public Service Award from the Federal Emergency Management Agency. Pilkey lives in Hillsborough, North Carolina.

Keith C. Pilkey is an attorney with a longstanding interest in geoengineering and corporate influence on science policy. He lives in Johnson City, Tennessee.

Mary Edna Fraser is an artist who highlights environmental concerns in large silk batiks, which are often based on maps, satellite images, and the photographs that she takes while flying her family’s 1946 propeller plane. Deemed a “pilot with a palette” by Michael Kilian of the Chicago Tribune, Fraser has exhibited widely, including at the Smithsonian National Air and Space Museum. Reviewing that show, Hank Burchard of the Washington Post declared that “the batiks amount to visual poetry.” Fraser and Orrin H. Pilkey are the co-authors of A Celebration of the World’s Barrier Islands. She lives in Charleston, South Carolina.

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GLOBAL CLIMATE CHANGE

DUKE UNIVERSITY PRESS

Contents

PREFACE...........................................................................xi1. GLOBAL CHANGE AND THE GREENHOUSE EARTH.........................................12. THE IMPACT OF GLOBAL CHANGE....................................................153. DOUBTS, UNCERTAINTIES, AND QUALMS..............................................294. THE MANUFACTURE OF DISSENT The Global Warming Denial Lobby.....................425. THE FUTURE OF ICE..............................................................536. GLOBAL CHANGE IN THE OCEANS....................................................697. DISAPPEARING CIVILIZATIONS.....................................................848. GLOBAL CHANGE IN THE BIOSPHERE.................................................989. PLAN B Geoengineering to the Rescue?...........................................110ABOUT THE ART.....................................................................123BIBLIOGRAPHY......................................................................131INDEX.............................................................................139

Chapter One

The Greenhouse Effect through the Ages

Ever since water accumulated to form the ocean, not long after the Earth formed 4.6 billion years ago, the level of the sea has been moving up and down. It was only in recent millennia, however, that such changes have affected human beings. For example, a few miles off the coast of Maine, fishers have been trawling up spear points, arrowheads, and other stone implements from a submerged village site, which was occupied eight to eleven thousand years ago. The people who lived at this site, now under a hundred feet of water, had to pick up and move inland as the sea level rose and the shoreline moved past their village. Almost certainly it wasn't just the gradual flooding by the rising sea that forced them to flee. Probably it was a storm or two that penetrated further inland than usual, or perhaps their drinking water became too salty because of the higher sea level. The effort required to move a prehistoric Native American village inland is a far cry from what would be required to relocate today's New England coastal settlements.

It seems that nothing is new under the sun. The temperature of the Earth's atmosphere, just like the level of the sea, has varied considerably over time. Most of the changes have occurred because of variations in the amount of heat received from the Sun, which are related to solar activity and the orientation of the Earth relative to the Sun.

Atmospheric temperature is also affected by the concentration of what scientists have termed greenhouse gases in the atmosphere. The greenhouse effect makes life on Earth possible. As solar radiation warms the Earth's surface, a portion of the Earth's atmosphere acts like a greenhouse and retains heat that would otherwise be lost back to space.

At the time of the dinosaurs, the Earth's temperature was much warmer. Now, 65 million years after the last dinosaur died, we have reached a very cool period known as the Ice Age. Even though we are currently in an interglacial time, between advances of the great ice sheets, it is a time that is too cool for cold- blooded dinosaurs in most of the places where they previously lived.

Sea level and atmospheric temperature are often related. When global temperatures cool, continental scale glaciers can form, and they can contain so much of what was once the ocean's water that they cause drops in sea level as large as four hundred feet. There have been at least seven major fluctuations of the sea over the last two million years.

At present the Earth's huge and ever growing human population is affecting the climate through (1) the emission of gases that cause the Earth to act like a greenhouse; (2) the discharge of high concentrations of atmospheric particles called aerosols; and (3) changes in land use. All three are interrelated and work in tandem to change the Earth's temperature.

A real greenhouse works differently from the Earth's atmosphere. Glass- enclosed greenhouses prevent winds from dispersing the heat created by the Sun's rays. Thus the interior space retains heat. The atmospheric greenhouse works because the greenhouse gases allow short- wavelength sunlight to pass through the atmosphere. This radiation is converted to heat, which warms the Earth's atmosphere, causing it to emit longer- wavelength infrared radiation back into space. The greenhouse gases absorb some of this infrared radiation heading out into space, which in turn heats up the Earth's atmosphere even more. Eventually the infrared rays escape the Earth, but the more greenhouse gases there are in the atmosphere, the more radiation is trapped, resulting in increased temperatures.

While the greenhouse effect is natural and necessary for human life, the fundamental problems are that human activities have created an excess of greenhouse gases in the atmosphere, and that the enhanced greenhouse effect has brought about global warming at a rapid and accelerating rate.

The Greenhouse Gases

So, what exactly are the major greenhouse gases? The principal greenhouse gases whose presence in the atmosphere causes warming are water vapor (H₂O), carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). All the greenhouse gases are "trace gases": that is, they all make up a very small part of the atmosphere. Carbon dioxide is usually measured in parts per million (ppm). Present measurements indicate that there are around 390 molecules per million molecules of air. Methane and nitrous oxide are measured as parts per billion (ppb). Even water vapor is a minor constituent of the atmosphere—at most a few percent.

Yet water vapor is responsible for most of the greenhouse effect, accounting for between 36% and 66% of the warming (average of 60% globally), but it is more or less a long- term constant in the greenhouse equation. That is, it is not directly responsible for the global climate change that the Earth is experiencing. Unlike the other greenhouse gases, which are uniformly distributed in the atmosphere, water vapor concentrations vary widely both in space and time.

A warm atmosphere is able to hold more water vapor. Warming of the atmosphere causes an increase in water vapor content, which in turn leads to more warming. Increased warming leading to increased warming is what is called a positive feedback. However, increased water vapor can result in decreased warming (a negative feedback) if more cloud cover is formed, because clouds reflect solar radiation, a distinct cooling effect. Clearly the role of water as a greenhouse gas is a complicated one and presents a problem for predictive mathematical models (as discussed in chapter 3).

The global warming potential of a gas (GWP in the accompanying table) is a measure of how much a gas is estimated to contribute to the greenhouse effect. The global warming potential depends on both the efficiency of the molecule as a greenhouse gas and the length of time it remains in the atmosphere. Both factors are summarized in the table, in which CO₂ is given an arbitrary value of 1 for the purpose of comparing it with other gases over a period of twenty years. The right- hand column in the table indicates that methane is 72 times more powerful as a greenhouse gas than CO₂ and nitrous oxide 289 times more powerful. Because CO₂ has a higher concentration than most other gases, its impact on global warming is largest, even though the other gases have a larger global warming potential. That is, a molecule of methane is a much more powerful greenhouse gas than CO₂, but it has less of an impact because a methane molecule resides in the atmosphere for only twelve years (this is its "lifespan," as shown in the middle column of the table) compared to thousands of years for a CO₂ molecule.

Carbon dioxide is the principal greenhouse gas villain because it is the gas produced most abundantly by human civilization in the modern era. Human activities produce eight billion tons of CO₂ per year compared to the largest natural source, volcanic activity, which accounts for less than a third of a billion tons. During the cold times at the height of the last ice age, the CO₂ content of the atmosphere was 180 ppm. The concentration has since progressed from 280 ppm in the period preceding the Industrial Revolution (the eighteenth and nineteenth centuries) to a present- day 390 parts per million—higher than it has been for 650,000 years (based on the study of air bubbles in ice core layers from Greenland). Based on measurements taken at the top of Mauna Loa in Hawaii, the rate of increase of CO₂ is accelerating and now stands at about 2 parts per million per year.

A decade ago a common assumption was that to hold back major and irreversible climate changes, excess production of CO₂ should be kept below 550 parts per million in the atmosphere (nearly two times preindustrial concentrations). The bill in the U.S. Congress known as the Waxman-Markey bill aims for 450 parts per million, and that target could require an 80% reduction in emissions by mid- century. Currently the atmospheric CO₂ concentration is approximately 390 parts per million. The nasa climatologist James Hansen argues that 350 parts per million is the concentration we should be aiming for and that anything higher than that (including the present- day concentration) takes us beyond a tipping point where irreversible changes will occur (for example, runaway melting of the ice sheets and rapidly rising sea levels). Hansen's call for a reduction in CO₂ to 350 parts per million in order to "preserve a planet similar to that on which civilization developed and to which life on Earth is adapted" has led to the creation of 350.org, an environmental organization headed by the author Bill McKibben.

That there is disagreement as to the precise parts- per- million number beyond which irreversible climate change occurs does not in any way detract from an important point: reduction of CO₂ in the atmosphere is an absolutely essential goal.

How do we know that the increase in CO₂ is not simply part of a natural cycle, as is commonly argued by climate change deniers? The best evidence that the CO₂ increase results from the burning of fossil fuels is the carbon isotope mixture in the atmosphere. Isotopes are two different forms of the same element, and carbon has two stable isotopes, carbon 13 and carbon 12. Plants prefer to take up a lighter mix of isotopes than is present in the atmosphere, that is, an isotope mix richer in carbon 12. Most coal and oil is derived from plants, so as these fuels are burned they contribute back to the atmosphere a relatively light mixture of carbon atoms. That the atmosphere is getting lighter in terms of its carbon isotope mix (with more carbon 12) is a measure of the contribution of fossil fuel burning.

Methane, the second- most significant gas for global warming after CO₂, has a total greenhouse effect about one- third that of CO₂. As can be seen from table 1, methane is a more powerful greenhouse gas (global warming potential of 72, compared to 1 for CO₂) but a less abundant one (14% of total greenhouse gases), and molecules remain in the air for only a short time (average lifespan of twelve years). Approximately 55% of the annual methane emissions into the atmosphere are from anthropogenic sources, the most important of which are energy production and the raising of ruminants (livestock). Natural methane emissions are primarily from wetlands, but agricultural sources other than ruminant livestock, e.g., rice paddies, also contribute to methane gas emissions.

During the last glaciation, methane was found at concentrations of 400 parts per billion (ppb). After most of the ice left, it rose to 700 ppb, and now, after the Industrial Revolution, methane has reached concentrations of 1,500 ppb.

The cycle of methane emissions is not as well understood as that of carbon dioxide, but climate change itself may soon unleash vast natural reserves of methane and thereby dramatically amplify the greenhouse effect. One particular area of concern is the thawing permafrost of the Arctic, especially in the vast tundras of Siberia. Melting of the ice contained in the soils will enhance the bacterial degradation of plant matter long stored in the soils, releasing not only potentially large volumes of methane, which is a byproduct of bacterial decay, but also long- dormant carbon dioxide molecules. The 2008 yearbook of the United Nations Environment Program warned that "methane release due to thawing permafrost in the Arctic is a global warming wild card," meaning that the potential volume of CH₄ release is very large and very damaging, but when it will be released remains a mystery.

The second, even larger potential source for methane gases is the methane hydrates or methane ice stored in the deep sea. On a local scale the massive oil spill in the Gulf of Mexico in 2010 released a lot of methane ice. In the cold Arctic, methane ice may be found in ocean waters as shallow as one hundred meters. Methane hydrates are huge deposits of methane produced by degrading organic matter that are maintained in a frozen, immobile state by the cold temperatures and high pressures at the bottom of the deep- water column (usually greater than one thousand feet). These methane ice deposits, which hold the potential for catastrophic global changes, are found on many continental margins, including those of eastern North America. They are also an important exploration frontier for oil companies, which see a huge energy potential in the deepwater deposits. Smaller but significant volumes of methane hydrates exist on land, beneath permafrost in the Arctic.

As the ocean waters warm or as warm currents change their trajectory (often a result of climate change), more and more hydrates will be released from the shallower deposits. Plumes of methane gas bubbles have been observed coming from the sea floor on the West Spitsbergen Arctic continental shelf, and very high concentrations of methane in seawater have been observed recently on the East Siberian continental shelf. According to Natalia Shakhova of the University of Alaska, eight million tons of methane escape every year off Siberia, an amount equal to what was previously assumed to be the total amount of methane released from all the oceans. In this case the methane is probably being released because the Arctic current has warmed over the past three decades, causing the release of methane by breaking down methane hydrate in the sediment beneath the seabed. This Siberian discovery is an example of the evolving nature of our knowledge of greenhouse gas emissions. We still have much to learn.

The sudden release of massive amounts of methane from marine methane ice is the suspected cause of two of the Earth's major extinction events. The Paleocene- Eocene Thermal Maximum of 55 million years ago led to the extinction of numerous marine and land- based organisms. In this instance the collapse of methane ice deposits seems highly probable as the cause of the occurrence of spectacular atmospheric warming, which took perhaps 100,000 years to recover from. The much larger Permian-Triassic Extinction Event 250 million years ago resulted in the extinction of 70% of all land vertebrate species. Although the cause is much less certain because the event happened so long ago, conceivably methane ice melting and a runaway greenhouse effect were behind it as well.

You can find dramatic videos on YouTube of scientists from the University of Alaska, Fairbanks, punching holes in frozen lakes and lighting up the methane released by melting permafrost, gas which is temporarily trapped by the ice.

Nitrous oxide is currently responsible for about 6% of the heating caused by greenhouse gases. It is a pollutant from industry and particularly from agricultural fertilizers. It is also released naturally from soils and from the oceans. Besides its role as a greenhouse gas it reacts with and destroys ozone in the atmosphere.

Freons are a number of compounds that have no natural source but are now in the atmosphere. These include chlorofluorocarbons (CFCS) used in refrigerators; their replacements, hydrofluorocarbons (HFCS); nitrogen trifluoride from flat-screen televisions; and halons from fire extinguishers. All are very powerful greenhouse gases (high global warming potential) but they occur in such small quantities in the atmosphere that to date their impact on warming has not been important.

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Excerpted from GLOBAL CLIMATE CHANGEby ORRIN H. PILKEY KEITH C. PILKEY Copyright © 2011 by DUKE UNIVERSITY PRESS. Excerpted by permission of DUKE UNIVERSITY PRESS. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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