Tuesday, March 31, 2009

Global Warming: Introduction

The intertwined problems of population growth, water shortages, and food shortages have been recognized for over one hundred years, and no one disputes that they are important global problems. However, until very recently much of the public was unaware of the related problems of peak oil and global warming. As a result, I will spend more time focusing on these less familiar problems.

At the time of this writing (2009), there is growing public acceptance of the reality of human-induced global warming. I would argue that the scientific community reached consensus in the late 1990’s on the reality of global warming, and in the early 2000’s on the idea that warming is primarily human-induced. As expected for an issue this complex, it is taking longer for the public to reach a consensus. This is not surprising, as the culprit is fossil fuel use, and there are extremely powerful and wealthy business concerns that have campaigned against this consensus to protect their profits. This situation closely parallels that of the tobacco companies in the 1970’s, who paid lobbyists and scientists large sums of money to spread falsehoods about the link between smoking and cancer (see the book “Thank You For Smoking” for an insightful and amusing illustration of how corporations conspire to hide the truth). Unfortunately, this has led to a politicization of the global warming issue. Although Al Gore did an admirable job of raising public awareness on this issue (for which he won the Nobel Prize in 2006?), his political associations led many to close their minds to the possibility that he was right. However, Al Gore did not invent the theory of global warming, nor did he participate in any of the scientific investigations; he was merely publicizing an issue that was hidden from view. Most scientists are not very good at public outreach, and they need well-known figures like Al Gore to carry their message to the masses. This effort has been only partly successful, so now it is up to scientists like me to help the public understand the reality and the importance of issues like global warming and peak oil.

The concept of global warming is really quite simple. Energy in the form of sunlight passes through earth’s atmosphere and heats the surface; the surface warms and gives off heat. Without greenhouse gases like CO2 in the earth’s atmosphere, that heat would radiate into space and be lost, and the average surface temperature of the earth would be only 0°F, meaning that all water on the earth’s surface would be frozen, and life would not be possible. Fortunately, the greenhouse gases in our atmosphere absorb and trap the heat, increasing the average observed surface temperature of the earth to a very hospitable 59°F. We are fortunate to have greenhouse gases in our atmosphere. However, like Goldilocks we need it not too cold and not too hot, but just right. If the concentration of greenhouse gases gets too high, it will be too hot for us.

Recognition of the greenhouse effect goes back to Joseph Fourier in the early 19th century, and the role of carbon dioxide (CO2) was identified in 1859 by John Tyndall. It was Svante Arrhenius in 1896 who predicted that human activities could contribute to the greenhouse effect, but it wasn’t until the 1970’s that scientists like Roger Revelle and Wallace Broecker began to raise the alarm. Their concern was based on measurements by Charles Keeling, who showed that CO2 concentration in the atmosphere was increasing at an alarming rate:

Fig. 1: http://en.wikipedia.org/wiki/File:Mauna_Loa_Carbon_Dioxide-en.svg

Although there are seasonal fluctuations related to plant growing seasons (see inset of Fig. 1), the long-term trend shown in red is of steadily increasing CO2 concentration. The measurements in Fig. 1 were made at the famous Mauna Loa observatory in Hawaii, but similar measurements have been made at many other observatories and show the same trend. So how is this related to human activity? In the Peak Oil section, we described how oil contains the energy of sunlight that fell on earth millions of years ago, trapped in organic molecules that were manufactured in plants through photosynthesis. The simplified chemical reaction is:

Eq. 1: 6 CO2 + 6 H2O + energy from sunlight = C6H12O6 + 6 O2

The glucose molecule C6H12O6 represents the organic matter that stores the energy in fossil fuels. When we combust fossil fuels, we undo the work of photosynthesis, promoting the reverse reaction by heating the organic matter in the presence of atmospheric oxygen so they react and liberate the stored energy. The troubling product of this combustion is CO2, which accumulates in earth’s atmosphere, leading to the steadily increasing atmospheric CO2 concentrations exemplified by Keeling’s curve (Fig. 1).

Another example of this delicate balance maintained by earth’s atmosphere is the oxygen concentration of the atmosphere. From Eq. 1 above we can see that combustion consumes O2 while producing CO2. Thus, we would predict that if combustion of fossil fuels are now the primary source of atmospheric CO2, then with time increasing CO2 should be balanced be decreasing O2 concentration in the atmosphere:

*Insert link to figure

The current atmospheric O2 concentration of 21% is just right for trees: If O2 rose to 25%, forests would burn after every lightning strike, but if it fell to 13%, we wouldn’t be able to start a fire. In fact, it is life that regulates the composition of the atmosphere, as illustrated vividly by James Lovelock’s conception of Gaia, which posits that earth behaves like an organism because it’s components act in concert to maintain life-support systems at optimal levels. Just as our body maintains a constant temperature of 98.6°F, the earth can maintain global temperatures within a narrow range that is conducive to life. How? Eq. (1) gives us some insight. Because temperature and atmospheric CO2 concentration are positively correlated, when CO2 is increased, then temperature increases, and the combined effect is to induce plant growth through photosynthesis (Eq. 1). This causes plants to extract greater amounts of CO2 from the atmosphere, thereby decreasing atmospheric CO2 concentration and therefore temperature. In effect the earth system works to counteract environmental changes, a process called negative feedback (similar to LeChatlier’s principle in Chemistry). Thus, life helps to regulate the composition of atmosphere and therefore helps maintain an optimal temperature, and the earth system of which life is a part is self-regulating (homeostatic). Essentially, the solid earth and atmosphere (geochemistry) and life (paleontology) have co-evolved.

If life maintains the composition of the atmosphere at an optimal level, why worry about greenhouse gas (CO2) emissions?

· They may exceed the capacity of the system to maintain constant temperature and composition

· They may kill coral reefs and other marine organisms

CaCO3 + H2O + CO2 = 2 HCO3- + Ca2+

· They could shut down the “ocean conveyor belt” and cause drastic cooling of Europe

· Severe weather events such as El Nino and hurricanes may become more frequent and intense

· Specific regions may become uninhabitable due to desertification

How do we know that the new CO2 added to earth’s atmosphere derives from human use of fossil fuels, rather than some other natural source such as volcanic degassing? There are several lines of evidence that clinch the case, two of which involve the use of carbon isotopes. When plants grow through photosynthesis (Eq. 1), they preferentially extract the light isotope 12C from the atmosphere, so organic matter has a low 13C/12C ratio. Volcanic degassing would not change the 13C/12C ratio of the atmosphere, but returning organic carbon back to the atmosphere through burning of fossil fuels should lead to a decrease in the 13C/12C ratio of the atmosphere, which is what we observe. Another carbon isotope found in the atmosphere is 14C, which is radioactive and has a half-life (the amount of time it takes for half of the 14C to decay) of 5700 years (*check; it continuously formed by cosmic rays in the earth’s upper atmosphere). Modern plants incorporate 14C from the atmosphere and are therefore slightly radioactive. However, the organic matter from plants that grew millions of years ago that is now contained in fossil fuels has no remaining 14C, so burning fossil fuels (as opposed to modern biomass) should cause a decrease in atmospheric 14C concentration, which is again what is observed[1].

So we can agree that CO2 is a greenhouse gas, and that human activity has increased the CO2 concentration in the atmosphere. This should lead to warming of the atmosphere, which will thermally equilibrate with the land surface and oceans through heat transfer, causing them to also warm. Thus, the entire earth will warm, as is evident in the following plot:


We can fit a straight-line to all of the data to obtain the red curve, which shows a ~150-year trend of increasing global average temperature. If we fit a line to the data from the last 25 years, we obtain the yellow line that has a steeper slope than the red line, suggesting that the rate of heating was higher in the last 25 years than observed over the 150-year period. This acceleration of warming to rates higher than ever recorded in geologic history is what has scientists concerned.

Global warming is documented by many global changes. Instrumental records (corrected for the urban “heat island” effect) and natural evidence (shrinking and thinning of Arctic ice, loss of Antarctic ice shelves, receding of most Alpine glaciers globally, lengthening of growing season, migration of animals & plants to higher latitudes, borehole measurements) all show that the earth’s surface has warmed 0.4-0.8°C (~1°F) during the 20th century. The probability that warming is real is > 99% (IPCC, 2007).

Why is the greenhouse effect so hard for humans to detect (Pollack, 2005)?

  • It is difficult for humans to focus on small incremental changes worldwide when big things are happening at home.
  • Our senses are tuned to detect rapid change (e.g., lobster in boiling water).
  • We can easily detect changes in weather (short-term), but not changes in climate, which is the long-term characterization of the average weather.
  • It becomes harder to interpret human-induced changes in climate when they are superimposed on longer-term natural changes (Milankovitch cycles, continental drift, and oceanic circulation patterns).
  • We are tempted to interpret short-term departures from the norm as long-term trends.
  • Small changes such as a 1° increase in average global temperature can have a large impact because the earth, like our bodies, is a complex, finely-tuned machine that cannot tolerate small changes in temperature.

What is Causing the Warming?

Possible causes of climate change include variable sun, strengthening greenhouse, increased atmospheric aerosols, and volcanic eruptions. Computer simulations based on real-world measurements show that the natural drivers, solar variability and volcanic eruptions, have actually caused earth’s surface temperature to decrease during the 20th century. Aerosols also cause cooling. Therefore, the only remaining cause of global warming is increased greenhouse gas concentrations from burning of fossil fuels.

*More to come...

[1] Note that it is the changing 14C content of the atmosphere that makes accurate 14C dating of material less than 100 years old impossible.

First Sustainability Book Blog

I just started writing a book on Sustainability, and decided a good way to get feedback from people as I write is to periodically post snippets to a blog.  If successful, this would be my first published book, although I have published many articles in the scientific literature. What I will post to the blog will be my first drafts of sections.  I have been working on the book for roughly ten days, and my time is limited because I have a very hectic schedule this semester, so the going may be slow over the next couple of months. However, I've completed most of the Introduction, which I will post here as my first entry. Comments and suggestions are welcome. I'm particularly interested in hearing whether people think they would find this book interesting and worth reading. Thanks for your input! - John


Our society faces some major challenges in the next few decades. Scientists are concerned about the availability of energy, water, and food needed for a growing population. Most of our energy comes from sources such as oil, coal, and natural gas that are non-renewable. Furthermore, use of those energy sources releases the greenhouse gas CO2 into the atmosphere. In the United States, our high quality of life derives from abundant, cheap fossil fuels. However, many scientists believe that global oil production recently peaked, and therefore oil will become less abundant and more expensive with time. This will cause a large increase in the cost of living because most of the goods we use and food we eat were produced and transported using fossil fuels. In the Age of Oil it was easy to get rich, but after the peak in oil production it will be hard to stay rich. This book has two target audiences: those who feel a moral obligation to help preserve a high quality of life for our offspring and future generations by living sustainably, and those who simply want to find ways to maintain their current high standard of living. The first group has likely already been convinced that our current lifestyle is not sustainable. The second group either doesn’t know or doesn’t care, but recognizes that they can profit if they acquire the knowledge needed to anticipate future economic trends shaped by availability of resources. As a result, I wrote the first few chapters of this book to convince those in the second group that our current lifestyle in the U.S. is unsustainable, and that we can expect shortages in energy, water, and food in the coming decades. These shortages will cause economic recessions and possibly depressions, and likely will lead to multiple wars (as wars are generally fought over resources). The following chapters are aimed at those in the first group who are willing to make small sacrifices in their personal lifestyles for the greater good. By reducing their consumption they can help society delay future shortages; on the plus side, they will be better prepared when the shortages come. The final chapters give some advice on how people in both groups can anticipate the global economic changes looming in the near future and best position themselves to adapt to those changes. We can’t completely avoid the coming shortages and the economic consequences, but we can lessen the fall; we can reduce the impact on individuals and on society as a whole, and (for those in group one like myself) improve the quality of life of future generations.

Why did I write this book, and what qualifies me to write it? I am a Professor in the Earth and Environmental Sciences Department at Vanderbilt University, specializing in Geochemistry. My work has focused on aspects of the environment and resource availability and quality (primarily water but also ore deposits and fossil fuels). After teaching about these topics for over twenty years, I realized that due to the exponential growth of human population and consumption rates we were likely to deplete some critical natural resources in the near future, and that could have very large economic and societal consequences. It now seems likely that oil will soon be in short supply, and oil shortages will limit the economic growth that has sustained the global economy for decades. The U.S. is the most powerful county in the world because in the 20th century it had abundant oil to jump-start its economic growth; we now use our power to maintain the flow of oil from other countries. Without oil, our economy and our power would whither. I have two children, and I began thinking about how all of this would affect their lives. Unfortunately, it doesn’t sound good for them. I believe that the world economy has peaked and will soon start a steady decline caused by oil shortages. Furthermore, the U.S. is particularly vulnerable because we currently consume roughly 25% of the oil produced even though we make up only 4% of the global population. I also recently became convinced that our use of oil and other fossil fuels is causing global warming, and it scares me that we are changing the earth on a global scale and we don’t really know how it will affect us. So our reliance on oil is doubly evil, as it makes us reliant on unstable foreign countries for supply and vulnerable to shortages, but it also makes changes on a global scale to a delicately balanced system that we don’t fully understand. Thus, it seems critically important to me that, first and foremost, we reduce our use of oil (we must also reduce coal use for other reasons outlined in chapter ?). This can be accomplished through conservation measures taken by individuals and communities, but on a the larger societal scale it requires policy makers to promote a switch to renewable energy sources (wind, solar, biofuels, geothermal, and hydroelectric) that don’t release CO2 to the atmosphere. This book aims to give citizens the tools they need to reduce their ecological footprint and achieve sustainability, and in the process save money and maintain a high quality of life. It will also educate citizens so that they can elect political candidates who acknowledge these problems and advocate workable solutions to them rather than ignoring them. The problem is that politicians are focused on the short-term, but we need to elect politicians who have the strength and foresight to improve the future and not just the present. As a patriot, I want to convince our government officials that to keep America strong in the future our country must greatly reduce the use of oil. This is a point that we all can agree on, liberals and conservatives alike.

In writing this book, I’m aware that some will view me as just another “Chicken Little”. It’s true that some environmentalists have been claiming for decades that “the sky is falling”, and much of the public (perhaps rightly so) treats this group like The Boy Who Cried Wolf. But remember that boy, and Chicken Little if I recall correctly, turned out to be right. And while scientists in the past have not been able to successfully predict the exact timing of resource shortages (e.g., neo-Malthusian scientist Paul Ehrlich lost to Cornucopianist economist Julian Simon when he bet that metals prices would skyrocket in the 1980’s (?) due to shortages), I believe their warnings about the future had merit. For example, everyone agrees that oil will become scarce in the future, but there is little agreement on when. To me it is important that people know that oil will become increasingly unaffordable during their lifetimes, so that they can prepare for these near-future shortages and not get caught off-guard. I should also point out that I am an optimist, not a pessimist. I believe it is in our power to solve the problems I discuss in this book. First, however, we must acknowledge that we have a problem, and then discuss possible solutions to the problem. The primary problem we will discuss in this book is our addiction to oil, or more generally fossil fuels. Like any addiction, the addiction to oil is unhealthy. It hurts us as individuals, and it hurts our country. It is like a disease, and because it such a dangerous disease, it must be countered with many different medicines, and almost certainly a change in lifestyle.

I also think it is important for people to understand the important role that science plays in our society, and that we can use the information provided by science to our benefit. Although topics like global warming can be complex, I’m convinced that everyone is capable of understanding the essentials. Knowledge helps turn citizens into wise voters who are well-equipped to make the right choices for themselves and their country. In this book, I use a minimum of jargon in order to make this important information accessible to all. Moreover, I think the reader will find that topics like global warming are fascinating, and the rapid growth of our knowledge in this area is truly exciting.

This topic is particularly timely because there is a fundamental shift in the approach the U.S. government is taking. Contrast the inertia of the Bush administration (reluctance to change from fossil-fuel economy) to what is occurring now: “It now appears,” Schneider writes, “that Obama plans to launch his presidency with a daring idea: To anchor the American economy with energy sources not derived from fossil fuels.” As Schneider notes, Obama is trying to establish a new paradigm: Instead of marginalizing environmental concerns, Obama wants the solutions to environmental problems to help drive economic growth. Read Schneider’s article here.

I’m also trying to bridge the gap between scientists and laypersons. I believe I’m well-qualified for this task because I am a geoscientist, but I am not an expert on the specific topics that comprise this book. That makes it easier for me to explain the science to my readers, because I am really explaining it to myself using the printed word. My goal is to draw on the most up to date and high quality papers from scientific journals to inform the reader. I will also try to show the connections between seemingly disparate developments in Environmental Science. This is a time of rapid advances in our understanding of the relationship between humans and the environment, and the public usually only catches glimpses of these exciting developments. I will try to approach these issues holistically, pointing out, but not dwelling upon, the problems, and focusing on the possible solutions.

This book is focused on the U.S., the most powerful country in the world and the greatest contributor to environmental destruction. My aim is the convince U.S. citizens that we must turn the boat around 180 degrees and use our strength to show the rest of the world the path to the future - we need to reassume the mantle of leadership.

*Introduce chapters

In the end, I think that our society will only take serious action on these environmental issues when they reach the crisis stage. So why read this book and try to anticipate the crises if we can’t contribute to their solution? The answer is simply that you will be better-prepared for these future crises, which will give you great economic advantages over the short-sighted. However, if in spite of my cynical predictions humanity summons the courage to make difficult choices, and the strength to alter the course, then I hope this book will have contributed to that transformation.

This book was conceived in spring of 2009 when I taught a new course called “Sustainability: An Environmental Science Perspective”. For the first term paper, I created an outline for a book titled “Future Trends: How to Live Sustainably” and asked each of the 16 students to choose a topic for their paper. Each of the student’s papers became a chapter in a book that we published online at http://sitemason.vanderbilt.edu/page/h5dg6A. I realized that there were no comparable titles in print, and recognized that our society had an unfilled need for information on this topic. The notion of writing this book was particularly appealing to me because I’ve always wanted to “make a difference”, and it gave me an opportunity to use some of my knowledge to help others. I dedicate this book to my wife Mary who has made my life worth living, and to my children Alicia and Austin, who gave me the inspiration to think and write about our shared future. I hope this book helps make their world a better place.