I really like Cosmos: A Spacetime Odyssey, which is a documentary series on Fox that features eminent astrophysicist Neil deGrasse Tyson. It does an excellent job of communicating, in a clear and understandable way, the cutting edge of what science has revealed about world and the universe . . . and, perhaps just as important, it communicates the sense of awe and wonder about our existence that drives so many of our scientists to probe into the unknown. It is a worthy successor to Cosmos: A Personal Voyage, the classic 1980 documentary featuring the late astrophysicist Carl Sagan.
Up until the most recent episode, my only complaint about the new series was its oversimplified presentation of the Galileo Galilei affair. It was a typical, secularist, ‘church bad, science good,’ kind of take. I’m not making apologies for the Catholic Church’s behavior at the time, which was horribly misguided and wrong, but there was more to it than ‘evil church stands against science.’ Nicolaus Copernicus—who first developed the heliocentric model that Galilei helped refine and confirm—suffered no such repercussions from the church, and in fact was much more strongly criticized by Protestants than by Catholics. Copernicus was himself a Catholic [and possibly a priest, although historians are divided on whether he was ever ordained]. His book, De revolutionibus orbium coelestium, was only censored by the church during the Galileo affair—more than seventy years after publication—and only until a few sentences indicating complete certainty could be revised or omitted, after which it returned to publication with the church’s imprimatur.
Regardless, I do have to raise some issues the most recent episode, “The World Set Free,” which focused primarily on carbon dioxide (CO2) and climate change.
In one segment, Tyson explained that permafrost in the arctic is melting due to human-caused global warming, which then releases the carbon stored in that permafrost from the remains of ‘animals and plants that lived thousands of years ago.’ This release then causes a CO2 feedback loop and worsens climate change. Okay, sounds reasonable. I’m with you. Except . . . most of the plants and animals buried in the permafrost must have gotten there when it wasn’t permafrost, right? A few species of plants and animals are able to survive on permafrost, true, but not many. The quantity of carbon that Tyson implied would be present would, I assume, have required a thriving ecosystem leaving huge quantities of carbon behind, which would mean that what’s melting now is stuff that, at some point in Earth’s relatively recent history, wasn’t permafrost at all. And that would indicate to me that the Earth has recently been as warm (or warmer) than it is today. Perhaps there is some other scientific explanation for this, but Tyson didn’t address it . . . which left his astute viewers to wonder about the apparent contradiction and, perhaps, begin to examine the credibility of the other assertions in the episode.
We already know that our current temperature averages aren’t particularly unusual—a fact curiously left-out of the episode. Two other ‘warm periods’ in the last three thousand years are well documented by historians and honest climatologists alike. The Roman warm period ran from about 250 B.C. to A.D. 400, and temperatures from that period (at least in Europe and the North Atlantic) were comparable to those today. The Medieval warm period took place between A.D. 950 and 1250, and, although climate reconstructions are notoriously inconsistent, the best estimates seem to show a ‘spike’ in temperatures similar to the one we saw in the 1980s and 1990s, followed by a plateau similar to the one we have seen for the last fifteen-plus years that went on for the rest of the period before temperatures began to drop back down. In other words, there is little evidence that the temperature patterns we have seen in the twentieth and twenty-first centuries are significantly different than those around the time of Christ, or in the eleventh and twelfth centuries . . . unless you do a Michael Mann-style cherry-picking of the data, aided by some mathematical trickery, to flatten the line and get the scary-looking results that you want. And we should all know that a little bit of trickery—like manipulating the scale on a chart—can make innocuous data look positively terrifying.
As is often the case in intelligent discussion of climate change, both ‘sides’ agree with the underlying premises. Facts are facts. The Earth got warmer over the twentieth century, before temperatures seemingly plateaued into the twenty-first. Humans drastically increased our CO2 emissions over the same period, pushing atmospheric CO2 to record levels for modern times. And the CO2 increases are almost certainly driven by human activity. As Tyson explained in “The World Set Free,” there just hasn’t been enough volcanic CO2 or CO2 from other natural sources to account for the increase. Both ‘sides’ can even agree that CO2 is a greenhouse gas and, depending on a million other variables, more CO2 in the atmosphere could lead to a warmer planet.
But to hear Tyson explain it, CO2 is the single essential ingredient in regulating the Earth’s temperature. This assertion should have made any scientist, Tyson included, wince . . . and should never have made it past the first script revision. CO2 is part of the equation, of course, but it is not even the biggest part. Water vapor is estimated to account for as much as seventy-two percent of the greenhouse effect in our atmosphere (Kiehl and Trenberth, 1997). CO2, on the other hand, accounts for something between only nine and twenty-six percent. Other gasses—methane, ozone, nitrous oxide, chlorofluorocarbon, hydrofluorocarbon, and others—account for the rest. Some of these are emitted into the atmosphere to varying degrees by humans, but water vapor—the biggest regulator of global temperature via the greenhouse effect—is basically a zero-sum game (remember the water cycle?). It largely regulates itself no matter what we do. If the earth warms up, more water evaporates into the atmosphere until it reaches the point that clouds block more of sun’s heat from getting in than they keep here via the greenhouse effect . . . at which point the Earth begins to cool, the water is more likely to revert to liquid form, the clouds thin, and the cycle repeats.
Should we reduce our carbon emissions? Yes. Do our emissions have an effect the temperature of the planet? Probably. But is the effect enough to matter? Maybe, maybe not. And there is certainly no evidence that drastic and immediate reductions—at a huge economic cost—are necessary to avert some vaguely-defined disaster.
We see little correlation between CO2 and temperature patterns over the last two decades, with CO2 continually trending upwards even as the temperature plateaus and possibly even begins to drop. The tenuous correlation over much of the twentieth century has not been shown to be causal. Climate models based on our old assumptions about what the temperature will do based on CO2 levels have not accurately predicted reality (see chart). We know that CO2 does less than we previously thought it did to increase the greenhouse effect. We know that that current CO2 levels—though artificially increased by human activity—aren’t far from the long-term norms over eons. We also know that CO2 is beneficial in some ways, and that life on Earth, plant and animal alike, flourished in periods with high volcanic CO2 levels in the atmosphere. We know that the current temperatures on the planet are within the long-term norms, and that the recent spike follows a similar pattern to previous spikes—including two in the modern era evidenced by both historical and biological records—that were not attributable to CO2, and certainly not to human CO2 emissions!
We also know that none of the predicted effects of climate change—melting ice caps, sea level rise, droughts, worsening hurricanes and storms, etc.—have come to pass. While arctic sea ice is indeed unusually sparse, we have seen record sea ice extent in the antarctic (comically trapping a ship full of climate change believers, and stymieing multiple rescue ships, in the middle of the antarctic summer). The handful of places that are actually seeing an apparent sea level rise are dealing with subsidence—i.e., the ground is sinking because of plate tectonics. Droughts are occurring at an average rate around the world. Hurricanes haven’t gotten any worse either—yes we had an epic year in 2005, including Hurricane Katrina, but it was followed by almost a decade of below-average hurricane activity. In fact, not a single ‘major hurricane’ (defined as Category 3 and higher) has made landfall in the United States since 2005.
Tyson implied in “The World Set Free” that we are at risk of turning the Earth into a hot, barren wasteland like Venus . . . but there is literally no evidence supporting that assertion. I guess you could project CO2 emissions out as a perpetual exponential increase thousands of years into the future and get some kind of result like that, but that would rely on a lot of assumptions that are extremely hard to support.
Consider what an 1880 chart of the horse population in major U.S. cities, projected through to 1980, would have looked like. In 1880, you could assume that people would buy horses in greater and greater numbers every year for the next century, and it might have seemed like a perfectly rational assumption that it would continue forever. But that chart would have looked hopelessly idiotic by 1910, not even half-way into the projection, as the Ford Model T went into its third year of revolutionizing personal transportation in America. And even if we had somehow never switched to automobiles, the human reproduction rates began dropping precipitously from the 1960s onward thanks to the ‘sexual revolution,’ and fewer people would have meant fewer horses—a plateau in the graph, not an exponential increase. This hypothetical 1880 horse chart would have been based on centuries of reliable data about how many people and how many horses there were in major cities, following a set of strikingly consistent long-term trends, and yet it would have been completely wrong.
Imagine how poorly a climate projection, produced without the benefit of reliable data and consistent trends, would fare in a hundred years.
It is truly unfortunate that the producers of Cosmos, and Tyson, decided to present the traditional climate change dogma uncritically . . . especially considering that it is looking more and more like that dogma is wrong. The process of science—a process that I learned about, in part, from Carl Sagan’s original Cosmos series—is about constant reevaluation and improvement. A theory that seems rock-solid today could, in the face of new evidence, become passé tomorrow, and an object of ridicule the day after. You develop a theory, and then you try to destroy it through rigorous testing and experimentation and observation. If the theory doesn’t hold-up under scrutiny, you revise it, or you abandon it. But a scientist—or an interested layperson like myself—should never become so attached to a theory that he can no longer see its flaws, and cannot accept evidence that might undermine or disprove it.
I don’t fault Tyson or the producers of Cosmos for presenting the current consensus view on climate change. Although the much-reported ‘ninety-seven percent of scientist agree’ statistic is a completely baseless exaggeration, it is true that a strong super-majority of climatologists, and a slimmer majority of scientists in other geoscience fields, agree that the Earth is warming, that the warming is caused by humans, and that it is dangerous. Mathematicians and statisticians who have studied the climatologists’ work, however, tend to be much more skeptical, and have found major shortcomings and anomalies in the methods used for climate reconstructions and projections. Also, it is worth noting that fewer than forty percent of meteorologists—fellow travelers in the atmospheric sciences—believe that man-made climate change is a serious danger. So yes, there is a consensus view, but it is not one that is particularly strong, it is not beyond critical examination, and it certainly should not be presented as undisputed fact. There are very good, scientific reasons to be skeptical about whether the Earth is warming in an unusual way, whether humans are responsible for it, and whether or not it matters much either way.
In other words, this is not ‘settled science,’ and Tyson knows it (or should, anyway). There are many valid criticisms of the long-held climate dogmas that were presented in “The World Set Free,” and they should have been given voice. The Cosmos series has done such a wonderful job of communicating how science works—including the countless missteps, dead-ends, and disputes that have occurred along the way. Today, we know that much of what we thought we knew twenty years ago about the Earth’s climate was wrong, or at least incomplete. This could have been presented straightforwardly and honestly as an example of our continuing progress. Some scientists today are bucking the ‘consensus’ of a broadly-accepted theory and adapting in the face of new evidence—just like so many of their predecessors, including many who have been featured in Cosmos as heroes. Maybe they’ll turn out to be wrong (though I doubt it). Either way, the serious conflict of views with regard to climate change is part of the process of seeking the truth . . . and it belonged front-and-center.
“The World Set Free” was an opportunity to show exactly how the scientific sausage gets made—through skepticism, through open-mindedness, through a willingness to accept the evidence even if it doesn’t fit the theory, through a willingness to be the ‘voice in the wilderness’ until you can amass enough evidence to convince your peers. And, shamefully, it was an opportunity missed.