Yep, it's getting warmer

In a recent issue of Science a trio of scientists who are experts on climate modeling and interpretations of data related to global climate summarize the best available information on variation in Earth’s surface temperature over the past half century or so. Their work addresses a controversial subject that those resisting the idea of global warming love to talk about.

Doubts about the reality of 20th century warming have been fueled by a veritable blizzard of misinformation and outright denial by politicians such as Senator James Inhofe and talk show hosts such as Rush Limbaugh and Glenn Beck. The political winds from the extreme right have been blowing so mightily against the notion of global warming that the front-runners in the race for the Republican nomination in 2012 seem to be obliged to join in the denialist chant. The American people are being deluged with misinformation and outright lies on this topic. It is thus worth thinking about the significance of this recent work by Santer, Wigley and Taylor.

One of the most difficult challenges in the entire business of drawing conclusions about Earth’s surface temperature is that there really is no single literal measurement that gives us the temperature of the planet. I wrote about this in Chapter 9 of my 2003 book, Making Truth: Metaphor in Science. When we want to measure our own body temperature, we insert a measurement device such as a thermometer, or one of the fancier digital probes, under our tongue, in our ear or up our rectum, as the case may be. The temperature we record in this way we take to be representative of our body as a whole. This works because our bodies are designed to maintain, as closely as possible, a single temperature throughout. But planet Earth is not like that. As I write this in Estero Florida the temperature is about 80 degrees Farenheit. At the same time, my daughter living in mid-central Illinois reports that the temperature there is about 11 degrees Farenheit. It is far colder still in Antarctica. No single value represents the surface temperature of the planet . For this reason, when we talk about the surface temperature of the planet we are using metaphorical language and thought. We talk aboutEarth’s surface temperature as though the planet were a small, temperature-controlled thing like a human body or a refrigerator.

To get to something that resembles a single value for the surface temperature, scientists began with simply averaging the temperatures measured at as many places as possible at the same time, and averaging over time as well. Before the modern age of satellite measurements the estimates were pretty crude. Consider that something like 70 percent of Earth’s surface is covered with water. How do we get sufficient measurements of the vast and varied seas to produce reliable numbers? And what about remote places that are not readily accessible, or crowded urban areas where human activity generates a good deal of local heat? With satellite measurements it has become possible to collect data over a short period of time that reflects surface temperatures
over most of earth’s surface. By averaging these in a suitable way, one ends up with a single number that we call the surface temperature of the planet. It’s a metaphorical entity, not a real single temperature, but its value over time can serve as a reliable measure of the change at Earth’s surface. However, the interpretation of satellite data is not entirely straightforward. A group of scientists at the University of Alabama at Huntsville concluded in 2005 from satellite data that the planet’s surface temperature had declined since 1979. This unexpected result was used to cast doubt on the reality of surface warming.

One of the hallmarks of good science is that controversial results are subject to reevaluation and continued exploration. The satellite measurements were a new technology, and many factors needed to be taken into account in interpreting the data. Climate scientists at a California laboratory identified two serious errors made by the Huntsville group in their analyses. These were acknowledged by the Huntsville scientists, who redid their recalculations. The corrected results showed a warming trend over the entire period 1979 to present. The revised estimate, following from critical scrutiny by other scientists, represents another step forward in our ability to measure and understand the evolution of the global climate.

Modeling the terrifically complicated global climate system is difficult. The challenge is to find a model that reproduces the historical record as well as possible, considering all the uncertainties,and then to use that model to forecast the future course of climate change, assuming various scenarios regarding levels of greenhouse warming gases, energy consumption, population growth and so on. The media are filled with confident pronouncements, for the most part self-serving, about climate change from political, ideological and financial interests. When we hear what people like Rush Limbaugh, James Inhofe or Newt Gingrich are saying or are ready to get behind, we need to ask what motivates them and what is their competence to speak on the issue at hand. We should also do that with respect to scientists, whatever the issue might be. Citizens need to go behind the one-liners of politicians and talk show personalities to learn what scientists think and the evidence that supports their views. There is no scientific conspiracy to deceive the public into believing that global warming is real, and that it has the potential to cause a great deal of human suffering. Scientists are just doing their work, trying to learn more about the way the world is.

An incredible amount of research across many scientific disciplines leads to an unambiguous result: the planet is warming, mostly because of increased concentrations of so-called greenhouse gases in the atmosphere. Denying this may be politically or financially expedient, but global warming is underway and it will gain strength with each passing year. How much adverse change occurs over the next 50 years and beyond will depend on whether humanity collectively decides to do something about continued generation of greenhouse gases. There is little hope for significant action in the near future. The 2011 Climate Change Conference in Durban, South Africa, just concluded with essentially no progress in setting mandatory goals for reductions of greenhouse gases. This should not surprise anyone. We humans have evolved to possess a strong consciousness of the future, but we still live very much in the present. Our proclivity to discount the future, particularly one so distant that we will not be there to live in it, prompts us to choose present needs and desires over future consequences of our actions. That seems to be the way it is with respect to climate change. As Kurt Vonnegut was fond of saying, “So it goes…”.

Doing science in a greenhouse

The recent furor surrounding the hacked e-mails from the Climate Research Unit (CRU) at East Anglia University has died down a good bit, but the effects of it will reverberate for a long time The e-mails reveal a good bit of small-minded belligerence toward some scientists whose views depart from the consensus position, and speak of excluding some of their work. The director of CRU, Phil Jones, has stepped down pending an investigation of the episode. Pennsylvania State University said it would review the work of Michael Mann, a faculty member cited prominently in the e-mail messages, to assure that it meets proper academic standards. Climate change skeptics have seized upon the disclosures as demonstration of what they have been saying all along, that the science behind the claimed anthropogenic changes to climate is dubious at best. Republicans in Congress are calling for investigations into the work of US scientists any way connected, inasmuch as they are likely to be supported by federal funds.

What can this episode teach us about the nature of scientific authority? Clearly the authority of many scientists identified in the e-mails has been substantially weakened, and, by association, that of the climate science community more generally. Analysis of this particular case can help us understand more clearly the boundaries between science and other social sectors, and point to how scientists should behave to sustain science’s proper societal roles (See Steven Shapin’s excellent essay on this subject, and the discussion in Imperfect Oracle).

Michael Gerson wrote in the Washington Post on December 11 about the melding of science and politics. In the interests of advancing the case for urgent responses to the threats represented by climate change, some prominent climate scientists “..appear to exaggerate their public certainty on disputed issues, shade the presentation of information for political effect, tamper with the peer-review process, resist reasonable requests for supporting data ..” He speaks of the insularity of the climate science community: “Climate scientists are clearly accustomed to deference. Theirs is a community coddled by global elites, extensively funded by governments, celebrated by Hollywood and honored with international prizes. But outside the Copenhagen bubble, the field of climate science is deep in a crisis of professional credibility, which many scientists seem too insular to recognize.” Gerson is not a climate change skeptic. His concern is that scientific objectivity seems to have been compromised by a drive for political and economic change: “But without trust in disinterested, scientific judgments on climate, most non-scientists will resist costly, speculative, legislative actions. When the experts become advocates, no one believes the experts or listens to the advocates.” He concludes that the climate scientists involved in the episode have diminished the authority of science more effectively than anyone else could have.

But Gerson’s position borders on saying that scientists’ expert authority is compromised whenever they move beyond the boundaries of their expert, or epistemic, authority to argue for what should be done in a given situation, as opposed to what is simply the case. In fact, there is a hierarchy of positions involved. At the first level the scientist is an expert, and exercises epistemic authority by reporting as objectively as possible on the scientific results. In the present case, climate scientists might offer expert opinions on the potential for climate change based on vast amounts of data accumulated on various aspects of the climate, and with the aid of extensively tested computer modeling of what future climate will look like given particular scenarios of fossil fuel use. If those opinions are a realistic representation of what the science community holds to be the case, we have a straightforward example of the exercise of epistemic authority. Beyond this a scientist can exercise moral authority, by moving beyond offering an expert scientific opinion to advise that a particular course of action be taken; in the present instance, to advise that certain policies should be established to mitigate the harmful effects of climate change. This effort to exercise moral authority presupposes the epistemic authority of the scientist. The scientist’s expertise plays a role, but in the broadest sense of making a moral judgment the scientist is no better positioned than anyone else in arguing for what actions should or should not be taken. A non-scientist acquainted with the results of the scientific studies might argue that, assuming a doubling of the carbon dioxide content of the atmosphere will result in an increase in the Earth’s surface temperature sufficient to cause much human travail, we should stop burning fossil fuels quickly as possible. In advancing the same argument, a climate scientist's view should not count for more than the non-scientist’s, since both are premised on the same scientific considerations. It's not that the scientist’s expert authority has been weakened, it is simply not the driving influence; in making the moral judgment the science is taken as a given, equally available to both scientist and non-scientist. Beyond this, the scientist and non-scientist alike can move to active advocacy in the public domain for the particular actions that were advised in the exercise of moral authority. In moving into this kind of advocacy, the scientist surrenders her credentials as a scientist; those have already been cashed out.

This of course all seems quite reasonable in the abstract, but when the topic is as huge, urgent and plagued with manifold complexities as climate change, distinctions become blurred. The differences between these different stances with respect to an issue of such wide social importance are not sufficiently appreciated, particularly by scientists. There is nothing inherently wrong in scientists getting caught up in political advocacy for causes that grow out of their scientific work. When they do so, however, they must reconcile themselves to the loss of much of their scientific expert and moral authority. When the arguments are flying back and forth as to what should be done, advocacy for particular courses of action is already premised on knowledge that is taken as a given. If the scientific basis for the argument is contested, we are back at the stage of shoring up expert authority. In the case of climate change, Senator James Inhofe, Glenn Beck and their ilk keep wanting to return the argument to that first stage. It has been tempting for climate scientists to depart from norms of objectivity and disinterestedness in the interest of protecting and enhancing their epistemic authority. But doing so has proven embarrassing for some, and damaging for science’s image as a reliable, trustworthy source of knowledge. Disagreements within the climate science community over data interpretations, adequacy of the models and the reality of human effects on climate are being thrashed out in a glass house. A lot of people are watching; science’s epistemic authority is being determined by what non-scientists can see of how science moves toward increasingly reliable knowledge. Climate scientists can help keep the focus where it should be by not providing further unfortunate diversions.