The Climate Fix

The star witness that day was James Hansen, a NASA scientist who had been studying climate since the 1960s. Hansen had decided that "it was time to stop waffling so much and say that the evidence is pretty strong that the greenhouse effect is here and is affecting our climate." Hansen emphasized three points in his testimony: First, "the earth is warmer in 1988 than at any time in the history of instrumental measurements"; second, "global warming is now large enough that we can ascribe with a high degree of confidence a cause and effect relationship" to the emission of greenhouse gases, primarily carbon dioxide; and third, the consequences are "already large enough to begin to affect the probability of extreme events such as summer heat waves."² The hearing's public impact surely must have exceeded even its organizers' expectations, as the temperature in the room and the scorching weather outside resulted in Hansen's testimony receiving wide coverage in the national and international media.

Not long after the hearing, S. Fred Singer, who like Hansen had spent much of his career as a government scientist and bureaucrat working on climate issues, published an op-ed in the Wall Street Journal critical of Hansen's testimony and the reception that it had received. ³ Singer, who had previously publicly questioned the science behind ozone depletion, acid rain, and nuclear winter (and who would later question the science associated with smoking policies), asserted that "more research is needed" before any actions are taken to reduce greenhouse gas emissions due to the very large uncertainties that accompanied the issue. The public battle lines had been drawn on a debate that had been emerging in fits and starts for several decades, if not longer.⁴

Looking back many years later, one observer remarked that the 1988 Gore-Hansen hearing "touched off an unprecedented public relations war and media frenzy," marking "the official beginning of the global warming policy debate."⁵ What's more, the hearing had all of the elements that would characterize the debate in the following decades. Politicians sought to stage-manage the scientific community to support their political ambitions. Leading scientists willingly played along, enthusiastically lending the authority of science to the political campaign. Opponents of action engaged the political battle through debates over science—primarily by seeking to raise uncertainty (or, perhaps more accurately, by offering a set of competing certainties) as the basis for opposing efforts to regulate or otherwise address ever-increasing amounts of carbon dioxide and other greenhouse gases in the atmosphere—even though they were and would continue to be representing a minority position on the science. The global warming debate was under way, and how it started set the stage for how it would be fought for the next several decades.

Because political battles over climate change have been fought through science since 1988, it is easy to lose sight of the fact that adversaries on either side of that debate have agreed about core aspects of the science since that time. As I'll argue, that core understanding is sufficient to form the basis for a commensense approach to climate policy. Such an approach will recognize that science can alert us to a potential problem and provide some insight about the consequences of different policy choices, but science cannot decide what choices we ultimately make.

A commonsense approach to climate policy will recognize that there are many justifications for addressing the multiple human and nonhuman influences on climate, and their possible consequences, that should have our attention. For example, in the coming chapters I will introduce a technical concept—decarbonization of the global economy—that lies at the core of any effort to address increasing amounts of carbon dioxide in the atmosphere. Decarbonization refers to efforts to reduce the amount of carbon dioxide associated with economic activity, recognizing that sustaining economic growth is a priority around the world. The world has been decarbonizing for more than a century, and there are good reasons to accelerate that process that have nothing to do with climate science. But I am getting ahead of myself.

I had learned scientific FORTRAN programming during the previous two summers while working in a similar student assistant role for researchers at Colorado State University, where my father was a professor of atmospheric science. The first scientific paper that I collaborated on was a result of that summer work. That paper reported the results of an investigation of the effects of fairly regular afternoon cloudiness—such as occurs in the summer when thunderstorms build regularly along the Colorado Front Range—on the orientation of fixed solar panels.⁶ We asked whether the solar energy collected by the panels would be enhanced if the panels were shifted east to face more directly the morning sun and away from the cloudier afternoon skies. Before doing the research I had thought that the answer was obvious: of course the panels should be shifted toward the sunnier morning skies. However, upon actually doing the math we learned that a solar panel facing due south still collected more sunlight than one shifted to the east, even under conditions of regular afternoon cloudiness. It was a pretty simple study, yet, for me at least, it delivered unexpected results. It was a good lesson that intuition or belief is very often not a good substitute for actually doing the research, especially for seemingly simple questions with seemingly obvious answers. The lesson was to do the math yourself.

NCAR in the 1980s was a special place. It was not an ivory tower, but it was pretty close to being one. It sits on a mesa above Boulder in a spectacular setting, dwarfed by the foothills yet brilliantly designed by I. M. Pei so as to fit into its surroundings. NCAR has been home to some of the world's greatest thinkers on environmental issues. When I was there in the late 1980s it was not uncommon for giants in the field of atmospheric sciences such as Walter Orr Roberts (NCAR's founder), Will Kellogg, Warren Washington, and Mickey Glantz to join student assistants and other research support staff for lunch and conversation in the cafeteria looking out over the plains at the foot of Colorado's Front Range. Other scientists who were at NCAR at the time included Steve Schneider and Kevin Trenberth, both fixtures of the climate debate before and since that time.

Schneider, a prominent voice in debates about climate since the early 1970s, was even an extra in Woody Allen's 1973 movie Sleeper, in which NCAR played a cameo role. The movie was set in 2173, and a few other NCAR employees were also cast as extras. Some bearded scientists didn't make the cut as extras, as Woody Allen apparently did not see facial hair as part of his vision of the future.⁷ Sleeper is part of NCAR lore, which holds that the institution provides a window to the future. A colleague once remarked to me that just about every leading scholar in the atmospheric sciences had come through NCAR at some point in their career for one reason or another. In that company, I had a front-row seat to watch the atmospheric sciences emerge from being an interesting and relevant area of scientific research to occupy a center-stage position in global political debate.

The late 1980s and early 1990s were heady days for the atmospheric sciences community. The issue of ozone depletion of the stratosphere due to chlorofluorocarbons (a human-made industrial chemical used in refrigeration and air conditioners) was the focus of international attention. The Montreal Protocol governing the production of CFCs was signed in 1987 and subsequently strengthened in later years. Also during that period, policies to address "acid rain," resulting from the emissions from power plants, were being discussed in the U.S. Congress as part of amending the Clean Air Act in 1990. Climate change was emerging as an important policy issue, but also one with the promise of considerable new funding for scientific research. The Intergovernmental Panel on Climate Change, which would share the Nobel Peace Prize with Al Gore in 2007, was begun in 1988, and the so-called Earth Summit in Rio de Janeiro took place in 1992. In 1990 the U.S. Congress passed the Global Change Research Act, which sought to create a comprehensive research program to provide useful scientific information to policy makers grappling with decisions about climate change. A few years later I would write my doctoral dissertation on the ability of this research program to support policy making. In short, this period was one that saw the atmospheric sciences take a prominent role in a range of policy issues of national and global importance.

While I worked as a student assistant at NCAR's Atmospheric Chemistry Division I had the opportunity to listen to the scientific staff as they discussed the relationship of science and politics, typically in the context of discussions of ozone depletion and the responses to it that were being debated at national and international levels. An overarching theme of these discussions among the scientists was that if only policy makers better understood science, then the process of policy making would be so much easier.

Armed with this insight, I decided that it would be valuable to gain some expertise in public policy before returning (I had thought) to a career in the physical sciences. I quit my NCAR student assistant job and was accepted into a graduate program of public policy at the University of Colorado. There I worked on a master's thesis in which I evaluated the performance of the space-shuttle program as compared to the initial promises that NASA had made to secure political support for the program. I worked under the direction of Radford Byerly, a physicist who had spent much of the previous decades as a highly respected congressional staffer for the House Committee on Science and Technology. Rad had come to the University of Colorado a few years before in order to direct a center focused on space and geosciences policy. But his tenure did not last long; in 1991, thanks to his rare knowledge of both science and politics, he was called back to Washington, D.C., to serve as the chief of staff of the Science Committee, under its new chairman, Representative George E. Brown, a Democrat from southern California.

Chief of staff of the Science Committee is a pretty plum position in the world of science policy, so Rad accepted the position and moved back to Washington. I was only halfway through my master's program, so it was potentially a great loss for me. I can only surmise that Rad must have felt guilty about leaving me middegree because he offered me a position in his office as an intern. Much like my student assistant work at NCAR, my duties as an intern for the House Science Committee involved doing the mundane, behind-the-scenes work that makes any large institution work. But thanks to Rad it also gave me a front-row seat to watch the political process in action, especially because Rad made every effort to have me sit in his office—like a potted plant, just taking up space—for important closed-door meetings and to have me tag along with him to meetings and events involving members and senior staff that I never could have observed otherwise.

I will never forget the eye-opening, even life-changing, moment when late one afternoon in Rad's office, the senior staff of the committee were discussing the relationship of science and politics following the visit of a highly respected member of the scientific community, who had come to advocate some political course of action. An overarching theme of this conversation among the staff was that if only scientists better understood policy and politics, then the process of policy making would be so much easier.

For me it was an "Aha!" moment. My experience at NCAR taught me that scientists thought that policy makers needed to better understand science, and my brief stint at the House Science Committee taught me that the policy makers thought the scientists needed to better understand policy and politics. This realization set me forth on a career in science and technology policy, studying (and participating in) that messy intersection of science and politics.

For instance, in the mid-1980s, when my own interests lay far from science and policy, focused instead on soccer and girls, my father wrote an annual article on the atmospheric sciences for the Encyclopaedia Britannica. In his 1985 article he explained that emissions of carbon dioxide to the atmosphere would cause a net warming of the Earth's surface due to the fact that it and other trace gases "act to reduce the emission of long-wave radiation out into space yet still permit solar radiation to reach the Earth's surface. This mechanism of heat increase is referred to as the greenhouse effect."⁸ In 1984 he wrote that the consequences of an enhanced greenhouse effect could be profound: "Unless mitigated by other results of human activities, such as reduced sunlight at the ground due to additions of aerosols to the upper atmosphere, this warming could result in major changes in climate patterns." ⁹ Mitigation policies typically focus on efforts to limit the accumulation of carbon dioxide in the atmosphere to some upper limit, a challenge described in technical terms as the "stabilization of carbon dioxide concentrations."

Understanding the challenge of stabilizing carbon dioxide levels in the atmosphere at a constant amount is really quite simple.¹⁰ Imagine you have a bathtub that is filling with water (Figure 1.1). The rising water prompts concern that the tub will overflow, flooding your house and causing damage. Fortunately, there is a hole at the bottom of the tub that is allowing water to drain out of the tub. But unfortunately, this will only put off for a short while the overtopping of the bathtub, as the water is draining out at a rate slower than it is filling. To make matters worse, the rate at which the tub is filling is slowly increasing as each minute goes by.

The challenge that you face is to keep the bathtub from overflowing. Based on the filling rate, its rate of increase, and the open drain, the only way that you can prevent an overflow is by reducing the net rate at which water is filling the tub to zero. In other words, for the water level in the tub to become stabilized at a fixed level, the water filling the tub must be coming in at less than or equal to the amount of water being removed.

A simple bathtub model approximates the dynamics associated with the challenge of stabilizing carbon dioxide concentrations in the atmosphere. Human emissions of carbon dioxide (which can be thought of as the water filling the tub from the spigot) are increasing and accumulating in the atmosphere. Scientists measure the amount of carbon dioxide in the atmosphere using the terminology of "parts per million," referring to the amount of carbon dioxide molecules in every million molecules in the atmosphere. At the start of 2010, these values were close to 388 ppm and growing at a rate of about 2 ppm per year during the past decade.

Carbon dioxide accumulates in the atmosphere due to anthropogenic (i.e., human) activities, primarily from the burning of fossil fuels and to a lesser degree from land-use practices such as clearing forests and tilling soil for farming. Several hundred years ago atmosphere concentrations of carbon dioxide were about 280 ppm, meaning that they have increased by more than 100 ppm in the time since.¹¹ The various human activities that lead to carbon dioxide emissions can be thought of as the spigot in the bathtub analogy from which the water is filling the tub. Atmospheric concentrations have increased because carbon dioxide accumulates faster than it is removed. Emissions are conventionally described in units of billions of metric tons (Mt, about 2,200 pounds), or gigatons. The addition to the atmosphere of approximately 7.8 Gt of carbon dioxide leads to an increase in CO₂concentration of 1 ppm.¹² Figure 1.2 shows the increasing emissions of carbon dioxide from the burning of fossil fuels.

Some of the carbon dioxide emitted to the atmosphere through human activity is absorbed by the oceans and by various processes of the land surface.¹³ Because the uptake of carbon dioxide is related to processes that change in complex ways due to growing carbon dioxide concentrations, projections of how much carbon dioxide will be taken up by the oceans and land surface in the future are necessarily highly uncertain.¹⁴ The fact that the oceans absorb carbon dioxide reduces the rate at which it accumulates in the atmosphere, which might be good news from the perspective of the atmosphere were it not for the fact that carbon dioxide absorbed into the ocean introduces a different suite of challenges because it leads to changes in the ocean's chemistry, with potentially harmful effects. With accumulating carbon dioxide emissions, unfortunately, the natural system provides no easy, short-term solution.

The ability of the land surface to take up carbon dioxide has been a central feature of international climate policies. If the land surface can store large quantities of carbon dioxide, then this would add some additional time for the global economy to decarbonize, as the amount of carbon dioxide accumulating in the atmosphere would slow down a bit. It is as if the hole in the bottom of the bathtub might be made a bit larger. Such proposals have been particularly appealing to those interested in preserving forests, which store large quantities of carbon (particularly tropical rain forests), as well as farmers, who are able to modulate the amount of carbon stored in their lands through different agricultural practices.