8.3: Metaphors

Metaphors can be superb communication tools. A metaphor compares one thing to another thing, often in a way that brings out hidden similarities or reveals unexpected resemblances that can aid our understanding. “We have our hands on the thermostat that controls future climate” is an effective metaphor because we are not used to thinking about thermostats and global climate together.

Here’s another useful metaphor. Imagine you are watching a majorleague professional baseball game. The slugger who is thought to be on performance-enhancing drugs hits a home run. Did the steroids cause it? Wrong question. You can’t be sure they caused it, because he was already a big-league slugger when he was clean. And even with the drugs, he can still strike out now and then. But at the end of the season, you see in his statistics that he hit more homers than he used to. The drugs increase the odds of home runs. If baseball does not interest you, other sports can be equally effective vehicles for this metaphor. A bicycle racer on illegal drugs does not win every race, but his chances of winning are increased.

Climate is the statistics of weather, and CO2 is the steroids of climate. The odds are higher now for all sorts of extreme weather because climate change has altered the environment in which all weather occurs. The entire hydrological cycle has sped up, there is more water vapor in the atmosphere, and so on. That’s why observations show that more precipitation now falls in heavy precipitation events than was the case a few decades ago. That’s also the reason for more high-temperature records being broken now than low-temperature records. After all, if the climate were not changing, neither warming nor cooling, but just randomly varying around a constant state, we would expect equal numbers of new high and low records to be set.

Figure 8.3.1 The catchy metaphor that carbon dioxide is the steroids of our climate is “sticky,” meaning that it is effective and easy to remember. Adapted from Shutterstock.

Figure 8.3.1 illustrates the catchy metaphor that carbon dioxide is the steroids of our climate. This metaphor is “sticky,” meaning that it is effective and easy to remember. Climate is a subject in which statistics and probability play a key role. Climate change involves changes in the odds of many weather phenomena, such as heat waves and heavy precipitation events. Communicating the science of climate change is aided by using metaphors that are widely understood and easily remembered. Baseball fans understand that a player using performance-enhancing drugs such as steroids doesn’t always hit home runs, but the drugs increase the odds of the player hitting home runs. A bicycle racer on illegal drugs does not win every race, but the drugs increase his chance of winning. In a similar way, adding heat-trapping substances such as carbon dioxide (CO2) to the atmosphere increases the odds of heat waves and heavy precipitation events.

We climate scientists sometimes think of ourselves as planetary physicians. I had a fascinating experience not long ago. My regular doctor retired. I had to choose a new doctor. When we met for the first time, my new doctor said, “Sit down. Let me tell you how I practice medicine. First, I’m competent. I know what I’m doing. Second, I’m honest. If there’s something I don’t understand, I’ll tell you. Third, I’m here only to advise you. You will make all the decisions.”

I was impressed. No doctor had ever talked to me like that. We climate scientists are planetary physicians. We are also competent and honest and here only to advise. We have learned many things about climate, but we still have a lot to learn. Like the findings of medical science, our understanding of climate, incomplete though it is, is already highly useful.

For example, the fundamental question—whether all of us, some 7.7 billion humans as of late 2018, have caused the world to warm up in recent decades—has already been answered. The answer is yes. We’ve settled that issue. At least, an overwhelming majority of the most active climate scientists involved in research consider it settled. Some other people may choose not to believe it. There are people, like Uncle Pete, who are unwilling to believe things that they wish were not true, or who just don’t trust experts.

The public has come to respect medical science, however. Although there will always be gullible people, most of us know there’s a difference between real experts and charlatans. Most people won’t listen to, or act on, medical advice from a quack who can talk about medicine but who isn’t really a physician. Everybody accepts this situation. Even the least enlightened members of Congress don’t hold hearings to denounce modern medical science as a hoax. Yet, a few politicians and others do denounce climate science in exactly this way.

Medicine is different. At your annual checkup, if you’re sensible, when the doctor tells you to lose weight and exercise more, you don’t argue. You don’t complain that medical science is imperfect and can’t yet prevent cancer or cure AIDS. You don’t label your doctor a radical alarmist. You know, and your doctor knows, that medical science, while imperfect and incomplete, is still good enough to provide advice well worth following.

Of course, some people just don’t do what experts tell them. Not everybody takes the medications their doctor prescribes. “Noncompliance” by some patients can be a big problem for physicians. We should keep all this in perspective. Lest we fall into the trap of thinking that medical science is a perfect role model for us climate scientists who crave more public esteem, it is also good to remember that it took a long time for many medical results to acquire widespread acceptance. Some scientists in the 1930s already suspected that tobacco caused cancer. The evidence was widely known to be strong by the 1960s. Yet the high-profile anti-tobacco lawsuits in the United States began only in the 1980s. Even today, many people still smoke.

The biggest single problem in human-caused climate change is carbon dioxide. We produce it when we burn oil and coal and natural gas to generate energy. It traps heat in the atmosphere, adding to the natural greenhouse effect and causing climate change. A few farseeing scientists realized more than a century ago that this might happen. Yet accurate measurements of carbon dioxide in the atmosphere began only in the late 1950s. Thus, we have known for only about half a century that the amount of atmospheric carbon dioxide is increasing. We ought to remember this half-century time scale when we get impatient about the slow pace of progress in action against human-caused climate change.

I would say that we scientists have known about the urgency of climate change for about 40 years. I have one especially important scientific research paper in mind, among many others. That paper, which is not very famous, is by Ulrich Siegenthaler and Hans Oeschger and was published in 1978 in the journal Science, which is often said to be the most prominent scientific journal.

The paper concluded that carbon dioxide emissions would have to peak and then quickly decline early in the current (twenty-first) century in order to limit global warming to moderate or tolerable levels. This 1978 result came from the simple models and the limited data available in the 1970s. We know much more today about the quantitative aspects of this prediction and many other details. However, the essential scientific foundation was already clear 40 years ago—or at least it was clear to two insightful Swiss scientists, Siegenthaler and Oeschger. That is the message I try to emphasize: the need to drastically reduce global heat-trapping gas and particle emissions is urgent, and the urgency is scientific, not political.

Incidentally, like many climate scientists, I don’t fully approve of the catchy term “global warming,” although I realize it’s in the language to stay. It’s an oversimplification. Climate isn’t just temperature. Climate is a rich tapestry of interlinked phenomena, multifaceted and inherently complex. The important aspects of climate change are local, not global, and are not confined to warming. Global warming is just a symptom of planetary ill health, like a fever.

You and your physician both know that fever is important but not the whole story. At your annual checkup, you don’t confine yourself to body temperature when discussing your health. Even the most ignorant patient realizes that measuring temperature alone doesn’t enable the physician to diagnose an illness and prescribe treatment.

Instead, everybody knows that a body temperature only a few degrees above normal is a symptom that can indicate health problems that may have serious consequences, including death. Yet we still haven’t educated most Americans to understand that a planetary fever of a few degrees can mean melting ice sheets, rising sea level, massive disruptions in water supply in the arid American west, increased risk of wildfires, killer heat waves, and stronger hurricanes on the Atlantic and Gulf coasts of the United States.

Figure 8.3.2 We climate scientists are planetary physicians. The decisions about caring for our patient, the Earth, will be made by its people and their governments. Climate science communicators must inform people and motivate them to act promptly, wisely, and forcefully. Reproduced from NASA.

Figure 8.3.2 shows the Earth in space, beautiful and fragile and vulnerable. Climate change threatens the well-being of all its plants and animals, as well as that of its 7.7 billion human passengers. The most important function of climate scientists and climate science communication is to inform people and to motivate them to act promptly, wisely, and forcefully.

What can we say about hurricanes and their possible connection to an altered climate? The short answer is that you have to think about probabilities when you think about this connection. A warmer climate means that the strongest hurricanes may become even stronger, on average. It does not mean we can definitely prove that any particular hurricane owes its strength to climate change, only that the odds of very strong hurricanes have gone up.

A hurricane is essentially just a heat engine with sea surface temperature as an approximate indicator of the fuel supply. The higher the temperature of the ocean surface, the more energy is available to power the hurricane. There is a critical sea surface temperature of about 80°F, below which hurricanes generally do not form. Because their destructive power increases as the sea surface temperature does, and especially because of the big recent increase in population and development in hurricane-prone areas in the United States, our vulnerability to hurricanes has increased strongly.

Scientists are cautious people, skeptical to a fault, fond of caveats, and not given to sweeping statements. We prefer to make claims only when we can back them up with solid data. We know that hurricanes are highly variable, no two are alike, and next year’s hurricane season might be very different from this year’s. It’s our natural inclination to wait a few more years, observe more hurricanes, improve our theories and models, until we have an airtight case to present.

Nevertheless, the best current research tells us that the oceans have recently warmed substantially, that human activities are the primary cause of that warming, that an increase in the intensity of strong hurricanes is the expected result, and that we have indeed observed an increase in the numbers of the strongest hurricanes. No amount of waffling over probabilities and statistics can obscure these sobering results.

Many intelligent people still laugh at the small numbers we use and think a global warming of a few degrees is trivial. They may say that moving from a colder city to a warmer one involves a much greater warming and is actually quite pleasant. These people just don’t grasp the crucial difference between local changes and global ones. They don’t realize that when the climate of the entire planet changes by a few degrees, enormous changes happen. Going into an ice age, to pick one example, involves a global cooling of only a few degrees.

Some people really think that a rapidly warming climate is just a minor inconvenience that can be handled by air conditioning and other minor technological fixes. This massive degree of misunderstanding may be due in part to a failure to educate people about science. It may also be the case that people have become confused by the widespread misperception that the science of climate change is immature, uncertain, characterized by raging controversy, and not to be trusted. An effective campaign of deliberate disinformation about climate science has helped spread this false impression.

Medical science has achieved a measure of pervasive respect that climate science can only envy. Journalists covering a medical discovery don’t mistrust researchers and don’t inevitably insist on hearing from “the opposing view.” When reporting on research showing the need for Americans to eat more sensibly and be physically active, the media doesn’t treat these advances in medical science in terms of a dispute. Journalists don’t feel obliged to seek out medical contrarians “for balance.”

There are many parallels between the climate change issue and medical topics. Maybe some can be useful in educating people and politicians. It has turned out to be frustratingly difficult to get people and their governments motivated to act to avert climate change. Yet people are intensely interested in threats to their own health. Many Americans have improved their health by making major changes in their personal lives, changes that are directly attributable to the results of medical science. Real progress has been made in making Americans, and their government, more aware of unhealthy behavior. The media, including public service advertising, together with organizations such as the American Medical Association and the American Cancer Society, have succeeded in raising many people’s consciousness about health.

In climate change, the comparable scientific organizations have made very little progress in persuading people. In fact, most of the professional societies that scientists like me belong to exist mainly to serve the scientific community. They organize conferences of researchers. They publish highly technical journals that only scientists can read. These societies have low profiles and are essentially invisible to the public. Most of these societies have tiny budgets and devote very little effort to outreach of any kind. Many appear to be politically inactive or naive.

It is also true that some powerful segments of industry vigorously oppose efforts to act and to publicize the scientific facts about climate change. However, business and industry are not monolithic in this respect. There are outstanding corporate champions of sound climate science, and we know that even the most retrograde segments of industry can change and become forces for progress, as notably happened in the ozone issue, for example. There, after it was scientifically proven that human-made chemicals were the culprit that caused the ozone hole, the industry that manufactured these chemicals changed its tune and developed safe substitutes for them. Governments and science and businesses cooperated, and humanity benefited.

In other cases, science and public concern have eventually triumphed over misguided opposition and propaganda. Numbers of smokers and deaths from smoking have been significantly reduced. Most Americans realize that smoking is dangerous and kills many thousands of people every year. They have learned this despite a highly professional and well-funded disinformation campaign mounted by portions of the tobacco industry.

Quitting smoking, like quitting using fossil fuels, is not easy to do, and in both cases the difficulty in quitting is immediate, while the most important benefits are all long-term.

The widespread public concern about the health consequences of smoking tobacco has led to political action, including warning labels on cigarettes, restrictions on advertising, and bans on sales to minors. The tobacco industry has repeatedly been defeated in court cases and has already paid large amounts of money as a result.

We see too the results of governments responding to public concern in the arena of promoting healthier food choices, including laws mandating truth in labeling and other actions to increase public awareness. These examples, and many more that could be cited, are direct results of medical science affecting public policy. People are persuaded that the science is right, and governments react to concern and pressure from citizens.

Science seems mysterious to many people, and it is not easy to penetrate the barriers of jargon and mathematics to explain the intricacies of computerized climate models or satellite climate measurements to a lay audience. Although very few people have a deep understanding of science or indeed any detailed familiarity with what researchers actually do, the public generally respects scientists and has confidence in the validity of their results. In fact, polls consistently show that scientists are among the most widely admired people in our society.

Risk is an inevitable aspect of life. Medicine involves risk. People tend to be realistic about the consequences of serious medical problems. They know that a bypass operation is major surgery. They accept the cost and the risk, understanding clearly that doing nothing also entails real costs and dangerous risks. They don’t expect that a simple bandage will cure a potentially fatal disease. As a climate scientist, I sometimes fear that we are wasting time arguing about which type of bandage is most attractive as a climate remedy, instead of facing the hard decisions, and the risks, that climate change demands of us.

You can’t fool Mother Nature. The climate system responds to changes in the levels of heat-trapping gases. The climate system is indifferent to economic concerns, political considerations, or societal implications. The climate system does not care about the details of cap-andtrade agreements, and it knows nothing about diplomatic niceties like protocols and framework conventions. The amount of carbon dioxide in the atmosphere is what matters to climate.

The laws of atmospheric physics, unlike government reports, are absolutely immune from political tampering. If humanity insists on adding heat-trapping gases to the atmosphere, there will be consequences. That’s just a fact. We scientists are busy researching the quantitative details, but we already know the big picture pretty well. If you see that a glib climate contrarian isn’t at all worried about doubling the amount of carbon dioxide in the Earth’s atmosphere, then start to think about tripling, quadrupling, and beyond. That is where we are headed, and our speed on this wrong road is actually still increasing. To have an effect, we simply must do more than make small token reductions in greenhouse gas emissions.

One of the towering heroes of climate science, my colleague at Scripps Institution of Oceanography and my friend, was Charles David Keeling, who died in June 2005 after nearly half a century of precisely measuring the amount of carbon dioxide in the global atmosphere. He was one of the greatest of planetary physicians. His legacy is summarized in a famous graph, the Keeling Curve, showing atmospheric carbon dioxide inexorably increasing, decade after decade. Those data are rock solid, real science, unassailable.

In the 1950s, at about the same time that Keeling’s measurements began, another renowned Scripps scientist, Roger Revelle, famously wrote that humanity is doing an inadvertent and unrepeatable geophysical experiment in moving so much carbon to the atmosphere so quickly. That perception, visionary at the time, seems obvious now.

What is still not obvious to many is that all of us are now engaged in a second global experiment, this time an educational and geopolitical one. We are going to find out whether humanity is going to take climate science seriously enough to act meaningfully, rather than just waiting around until nature ultimately proves that our climate model predictions were right.

In the end, our success or lack of it will be measured by whether we as a global society can change the Keeling Curve, bending it downwards, and whether we can stabilize the amount of carbon dioxide in our atmosphere in time to avoid the most dangerous climatic consequences. Whether that will turn out to be possible is not yet known. I hope so. I think it is the single most important question in planetary public health: armed with impeccable science, can humankind muster the wisdom and the will to make difficult changes? With many other medical decisions, the outcome is ultimately in the hands of the patient. In this case, it depends on all of humanity.

The biggest unknown about future climate is human behavior. Everything depends on what people and their governments do. For centuries, we humans were passive spectators at the global climate change pageant. Not any longer! We have become the dominant actors. You and I, and all 7.7 billion people who are alive today (late 2018), do indeed have our hands on the thermostat that will control the climate of our children and grandchildren. “The thermostat” is a powerful metaphor, illustrated in Figure 8.3.3. It is very useful in climate change science communication. People know that a household thermostat enables a person to control the temperature of the interior of a building. Yet many people do not realize that human activities are now a dominant factor in controlling climate change. We humans have caused the world to warm in recent decades. We human beings now have the power to limit the warming, to turn down the thermostat, and to avoid some of the most disruptive consequences of severe climate change. The big question is whether we together can muster the will to act promptly, wisely, and forcefully.

Figure 8.3.3 We have our hands on the thermostat that will control the climate of our children and grandchildren. Reproduced from Fotosearch.