Value Judgements by Scientists

In this essay, I present an argument for scientists to withhold their personal value judgments when reporting scientific results to policy-making organizations.

A few months ago, I was the shipboard geologist on an ecocruise to Antarctica.  My responsibilities were to give a few lectures and explain the geology to the guests at our landings.  I gave a couple of lectures on the geology of the Antarctic Peninsula, the part we were going to see, and also one on my specialty, which is climate change in deep time (Earth history before the Ice Ages).  For the latter, I started by explaining how climate works (to the extent we know it) and how we know what we know about past climates. This was an hour-long lecture and I’ve written a whole book on the subject of how we know what we know, so naturally, this was a highly condensed summary.  I also wanted to walk the guests through the history of climate on Earth as we currently understand it, another huge topic.  As part of this narrative, I presented a summary of the evidence for human influence on climate.  Then I prepared myself for what I’ve come to think of as “The Question”, that is, what I think of climate change and whether humans are causing it.

Background

I’ve worked on long-term climate change for more than 40 years.  Even though I trained as a geologist and biologist, I taught myself the basics of fluid dynamics and atmospheric science in order to be able to pose fundamental questions about climate change in deep time.  I was fortunate to land as a postdoc in A.M. (Fred) Ziegler’s research group at the University of Chicago.  They were reconstructing the positions of the continents through time.  When I started in 1977, continental drift was still a hot topic and several groups around the world were attempting to figure out where the continents had been at various times in Earth history.  One of those groups was at the University of Chicago, and by the time I arrived, the geologic community was starting to get a pretty good handle on where the major continents were, even for times as distant in the past as the early Paleozoic Era.

Major features of atmospheric circulation are largely dependent on three things: the equator-to-pole temperature gradient (which is caused by differential insolation, with more sunlight reaching the equator than the poles), the rate of Earth’s rotation, and the positions of continents and oceans, specifically, the thermal contrast between land and water.  Thus, knowing where the continents were is essential to understanding global climate patterns in the past.  My work as a postdoc was to model atmospheric circulation and predict (or “postdict”, as my postdoc advisor kept reminding everyone) where ancient upwelling zones occurred.  Upwelling zones are areas of the ocean that have very high biologic productivity, so high that, when upwelling occurs over the relatively shallow waters of the continental shelves, much of the organic matter ends up in the sediments and eventually can become the source for petroleum.  My models were conceptual—meaning they could predict only patterns, not numbers—but turned out to be very successful and useful for predicting the locations of ancient upwelling zones, as well as for identifying other interesting paleoclimate problems, some of which I’ve pursued for most of my career.

Not only was I fortunate to have landed at the University of Chicago, where the department includes both geology and atmospheric sciences, I was one of only two people at the time trying to systematically model climate patterns in deep time.  The other person was consumed with trying to wrestle computer models of atmospheric circulation that were designed to predict weather into more generalized models that could respond to different boundary conditions—such as differing positions of the continents—for which they were not initially designed.  That took a lot of work, so he did not have as much time to ask questions of the geologic record as I did.  One consequence of this was that geologists around the world from different specialties saw me as more accessible and provided me with the opportunity to apply my models to their problems and to learn more about their specialties.  The result was that I learned a lot about how climate is recorded in the geologic record, enough to write that book.

Climate Change Becomes a Hot Topic

In 1988, James Hansen and colleagues at the Goddard Institute for Space Sciences devised a method for calculating (not measuring) average global temperature and concluded that the Earth was warming because a few of the previous years were the hottest ever recorded.  I emphasize “recorded” because humans have not been recording temperatures for very long, and the records that Hansen’s group could rely on represent an even shorter time series (more on this later).  Nevertheless, Hansen got a lot of press, and the discussion about global warming was on.  

Starting in 1989, I sat on three advisory panels at the National Science Foundation, and Hansen’s conclusions were all the buzz.  Suddenly, scientists were arguing for money to study global warming, and every other proposal that came in tried to relate the proposed research to the study of climate—it almost didn’t matter what discipline the proposal was in.  Many of these attempts were strained to the breaking point, but scientists could see money—big money—coming down the pike and were scrambling to tap into it.  Where there is money, there is politics, and I tried to raise the alarm as early as 1990 that this was politicizing science in a potentially unprecedented way.  I was ignored, and the rest is history.  Anyone who denies politics is not an integral part of the entire discussion of global warming (now climate change) hasn’t been paying attention.  

Of course, politics has long played a role in science, but this form of politicization seemed to me to be particularly perilous to science because it was like a mass case of confirmation bias.  If you found evidence for global warming or, even better, could predict catastrophic consequences of global warming, your funding stream was assured.  If not, you might as well find something else to do.  It is hard to overstate just how important this change was.  Even though I could and did take advantage of this money gusher, it still alarmed me.

None of this is to say that we haven’t learned a lot about the atmosphere and climate as a result.  There is no question we have.  We also keep learning more and more about what we don’t know.

Climate Change from a Geologist’s Standpoint

For reasons that continue to escape me, the statement “climate has always changed and is always changing” is considered to be a marker of a climate denier.  In all my travels, all the conferences I’ve attended, all the people I’ve met, regardless of their politics or training, I’ve never met a climate denier.  Of course climate has changed and continues to change.  

When I gave that lecture on the ecocruise, I emphasized a few observations about the history of Earth’s climate that very few people know because they just aren’t reported.  I emphasized climate history for the last 550 million years, give or take, because we know more about that time period (called the Phanerozoic Eon) than we do about earlier times and because the Earth system underwent some major changes earlier but has remained relatively—I emphasize relatively—consistent since.  These well-established observations are:

1. We are in an Ice Age, and ice ages were rare.  Only three times in the last 550 million years has the Earth had significant land-based ice caps.  The Ordovician glacial period, about 440 million years ago, was quite short, a couple million years at the most.  The glacial period centered on the Permian-Carboniferous periods (roughly 300-250 million years ago, but arguably starting as early as 350 million years ago), lasted longer, as long as 100 million years altogether, but almost certainly consisting of several “ice ages”, during which the ice caps advance and retreated.  The current glaciation started around 30 million years ago, but as most people know, definitely consisted of multiple advances and retreats of the glaciers.  Thus, at most, the Earth has had significant land-based ice caps for only 132 of the last 550 million years, and probably much less.  Although ocean-based ice caps, such as the Arctic ice cap today, are consistent with cooler temperatures, they have no effect on sea level.

2. Geologists have figured out how to estimate carbon dioxide in the atmosphere for the past using a variety of methods.  Even with the addition of anthropogenic carbon dioxide, the carbon dioxide content of the atmosphere today is the lowest in Earth history except for a period just following the end-Permian extinction event and very early in the Phanerozoic (that is, around 550 million years ago).

3. Climate changes in deep time have been far, far larger and at times as rapid or almost as rapid as the change we’re seeing today.  Some of these likely caused mass extinctions, although most mass extinctions were probably the result of many factors coming together.  This is why the phrase “ever recorded” is critically important—we simply have not been able to measure temperature for more than a couple of hundred years, and the kinds of data used to “measure” average global temperature (which is a calculation, not a measurement) have existed for just a few decades.  Against 550 million years of climate history, this is nothing.

The Question

On that ecocruise, I anticipated being asked what I think about climate change and whether I think humans cause it.  Because of my expertise, I have been asked many, many times, and I was not disappointed.  

Only fairly recently has there been some solid evidence of the scale of the contribution of human activities to carbon dioxide in the atmosphere (through the use of stable isotopes of carbon).  But everything else that we think we know is based on limited observations plugged into complex models.  There are two reasons to be circumspect about the model results.  First, we have only measured what we can measure and no measurement can take in the complete range of variability of any characteristic of the Earth climate system, so the measured results that we plug into the models are only a small part of the complexity of the climate system.  Second, models themselves are very limited, not least because (a) there’s a lot we don’t understand about the climate system and (b) we can’t yet model some processes, like clouds, that we know are really important.  And models themselves are kind of black boxes and can be pretty quirky.  The best source I’ve seen on this for non-experts is Unsettled: What Climate Science Tells Us, What it Doesn’t, and Why, by physicist and former Deputy Secretary of Energy (under Obama) Steven Koonin.  I won’t repeat his arguments here.  None of this is actually controversial.  Among themselves, climate scientists openly discuss these limitations.

So how do I answer the question about climate change and human influence on climate?

I don’t answer that question--usually.  Here’s why not:

A lot of people who ask aren’t really asking—they’re looking for a fight.  They are utterly convinced that the Earth is headed for destruction and that humans are the cause; this group of people includes many of my fellow scientists.  Nothing I say, if it contradicts their worldview, will influence their thinking, including the observations I stated above, all of which are well established.  Because those observations contradict their worldview, not only will the facts make no impression, they are likely to enrage the asker, whose critical faculties sometimes appear to flee.  I once was confronted by a volcanologist, who has spent zero time studying climate change, lecture me about the effects of carbon dioxide, citing T.C. Chamberlain (founder of the Department of Geology at the University of Chicago, as it happens), who did indeed argue that carbon dioxide is a greenhouse gas and might have influenced climate--in 1899.  As if we have learned nothing about the effects of carbon dioxide in the last 124 years.  This lecture was triggered by the mildest of statements of my opinion.  I’ve had enough of such fruitless discussions.

If people seem genuinely interested in learning, I will talk about what we know about past climates, including the observations outlined above, and why it’s important.  I’m also careful to let the askers know what we don’t know, either.  For example, one thing people cite as being proof that today’s rise in temperature is catastrophic is the rate of change.  While it is true that we have not found a comparable rate of climate change in the geologic past, that’s not because it didn’t happen.  It may (or may not) have happened, but we don’t have the tools to resolve geologic time that well yet.  It is also true that the better our ability to date events in the past gets, the more rapid some of these changes become—in other words, the changes are always more rapid than our ability to resolve them.  A couple of examples are the so-called PETM, a very rapid hot temperature “spike” about 56 million years ago and the Younger Dryas, a very rapid cold “spike” around 12,000 years ago, neither of which we really understand.  Interestingly, humans were around for the Younger Dryas and came through that climate catastrophe just fine.  (Indeed, I’ve heard it argued that one reason humans are so smart and adaptable is because we evolved physically and socially during some pretty unstable climates, but that is outside my area of expertise.)  We do know from first principles about another very rapid event, the impact of an asteroid with the Earth, which is thought to have led to the extinction of the dinosaurs, among many other animal species.  That had to have occurred within a day.  The climate consequences of that event had to have started immediately and been profound, and we know they carried on for hundreds of thousands of years.  I find it quite interesting that no one has apparently asked the question of why the Earth and life weren’t completely destroyed during that event, which was genuinely sudden and catastrophic, and against which the global warming today so far pales in comparison.  

The Role of Scientists in Society

Other than wanting to avoid unpleasant conversations, why am I so circumspect about stating my opinion?  For a couple of reasons.  One is I want to preserve my credibility as a scientist.  The other is that my opinion is just that, an opinion.  It is not fact, nor is my opinion more valuable or important than any other citizen’s.  

The science around climate change has become too political.  This means that if I even hint at something that goes against the opinion prevailing in the person or group with whom I am speaking, they are less likely to listen than they are to start questioning my credibility as a scientist.  If I discuss climate change as it relates to the Navajo Sandstone (the formation that makes up most of Zion National Park and that has been a major focus of my research in recent years), no one doubts my credibility, not just because they know they don’t know as much about paleoclimatology as I do, but also because I have had a long, productive, and honored career as a paleoclimatologist.  But if I try to discuss climate change in the past and why it’s relevant to what is going on today, at the slightest contradiction to the prevailing views, I suddenly know nothing (in their eyes).  I’ve seen outstanding and respected scientists—Judith Curry, Richard Lindzen, and many others—dismissed wholesale in just this fashion.  

More concerning, however, is that some might take my opinion too seriously.  Wait, you ask—isn’t that what you want?  No, it is isn’t.  Here’s why:

The role of scientists in society is to explore the natural world and learn as much about it as we can.  Some of this is curiosity-driven science, in which we discover what we can about what is still unknown, regardless of the topic.  Some is practical, such as learning how to find oil or cure cancer.  But all of it is highly technical—it takes years of education and experience to know how to ask the right questions, to learn to avoid bias, to develop the skills necessary to do good science.  And, most importantly, we must report our findings.  That is our role—to expand human knowledge and understanding of the natural world.  Always, we need to be humble about our findings at any given time.  The more complex the system we study—and nothing is more complex than the climate system except maybe the human body—the more modest we need to be.  That doesn’t mean we lack confidence, just that we know how incremental the accumulation of knowledge can be and how uneven the path can be, replete as it is with missing steps and switchbacks, especially when we study complex systems.  We also need—especially need--to be transparent about the limitations and error bars on our conclusions.  

With knowledge about systems that can have an enormous impact on society, we have to be especially careful because how humans use this knowledge does not involve just science.  Even if the use of scientific knowledge could somehow be founded solely in science—and I don’t believe it can be—imperfect knowledge, which the knowledge of complex systems will always be, can lead society down some wrong path of action, just as scientists studying such systems occasionally go down a wrong path of inquiry.  But in fact the use of scientific knowledge requires consideration of economics, politics, sociology, even philosophy.  I am an expert in my area of science; I am not an expert in economics, politics, sociology, or philosophy.  

As a citizen, I am entitled to my opinion, which is the consolidation of not just my scientific knowledge, but my views on economics, politics, sociology, and my personal philosophy.  In my role in society as a citizen, I vote based on all those views.  But in my role as a scientist, I must stick to what I know.  That I am a scientist and know things about the natural world does not mean that my opinion is any more valuable or credible than any other citizen’s when it comes to how humans should respond to climate change.  In my opinion (see what I did there?), no scientist should pretend that their findings point to some inevitable societal behavior that they will dictate.

Recently, a reporter asked me about the boundary for the proposed Anthropocene Era.  The boundary is marked by numerous indicators of human activity, including radionuclides formed in atomic explosions, fly ash, and other chemical and physical traces.  He asked me whether the mark humans have made in the geologic record represents the power of humanity or the hubris of humanity.  This how I answered:  “You are asking me to make a value judgment.  Value judgments are both personal and societal.  My personal value judgment should carry no more or less weight than yours or that of any other individual, even though I am a scientist.  In the US anyway, we all have a vote; the societal value judgment is the collective judgment expressed through those votes.  Why do I make such a big deal of this?  I am an expert and a pretty good one in science (specifically, climate change over long time periods).  But the value judgment about the societal implications of a scientific finding must necessarily bring in other issues on which I am NOT an expert, including politics, economics, philosophy, sociology, and so on.” 

Science and Public Policy

Does all this mean I think scientists should not serve on policy advisory panels or that there should be no positions such as science advisor to the president?  Not at all.  In policymaking, everyone needs to be at the table.  I am simply arguing that science and scientists should not act as, nor should they be held up as, any more authoritative than anyone else nor should their views be regarded as of higher priority or greater weight than others.  For example, it is much more a philosophical than scientific question whether humans are simply another organism that is part of the global ecosystem or are, among all the other organisms, uniquely pernicious.  

While remaining conveyors of scientific knowledge, scientists also need to be aware of and not play into potentially harmful sociologies.  For example, Nicotra and Parrish (2010) discussed the phenomenon of a dromocracy:

[T]he chronotope of time-space compression or Gegenwartschrumpffung has been up to this point most effectively deployed by the government and corporate interests to overwhelm more reflective decision-making processes and push through controversial or problematic agendas with the tacit consent of the public. In his article “A Clockwork War,” Stahl…named this authoritarian use of temporal appeals to circumvent the democratic process the “dromocracy.” A dromocracy (the root of which is the Greek word dromos, meaning “race” [as in “footrace”]) creates its authoritarian character through speed. Where the deliberative process at the heart of democracy, being slow by nature, requires a great deal of time, dromocracy relies on the use of use of temporal tropes like “the ticking clock” and “the deadline/countdown” to more efficiently ram through actions that the government wants with less resistance from the people.  A public that has been made to feel the pressure of time is less likely to deliberate and more likely to simply grant the government authority to take action. 

Conclusion

Although scientists bring much to the table for the use of society, we have expertise only in science, not in all the other disciplines that inform societal action.  Our role is to provide information—full and transparent information that includes forthright statements of the limitations of our knowledge, presented with humility.  

Judith Totman Parrish

Professor Emerita, Earth and Spatial Sciences, University of Idaho

References

Nicotra, J., and Parrish, J. T., 2010, Rushing the cure: Temporal rhetorics in global warming discourse: JAC—Rhetoric, Writing, Culture, and Politics, v. 30, p. 215-237.