Do Scientists Ever Change Their Minds? A Flashback to Nuclear Winter

Of course we do!

We scientists get accused of thinking that we know all the answers, but among the scientists I know, this is not the case. It is particularly evident among global-warming denialists: they think that the 99 percent of scientists who accept Global Warming science are closed minded and totally unwilling to consider the facts as presented by the oil companies and the think tanks that they sponsor.

But I have a story to tell that only my older readers will remember, a story that shows how scientists can, in fact, change their minds. It is the story of Nuclear Winter.

The concept of Nuclear Winter entered scientific and public consciousness with something of a splash. In a 1983 issue of Science, two days before Christmas, a pair of articles appeared. The first one claimed that a nuclear exchange between the United States and the USSR would put so much smoke and dust into the air that sunlight would be blocked and the surface of the Earth would freeze. In fact, it would freeze so deeply that it would never thaw. This is because ice reflects sunlight into outer space. A planet covered with ice could not warm up because it would reflect all the sunlight that it would need in order to warm up. The authors did not consider the “dirty snow effect,” in which the dust and smoke would settle on some of the ice, absorb sunlight, and melt the ice, to be important. This one paper, written by Turco, Toon, Ackerman, Pollack, and Sagan (yes, Carl Sagan)—referred to by cognoscenti as the TTAPS paper—painted a stark picture of the fate of the Earth that had not been considered previously. The second paper detailed all the extreme consequences that such a deep freeze would have upon all life on Earth. Merry Christmas, everybody!

By 1984 everyone was talking about nuclear winter. I did not think about it very much, until I had sort of a political conversion experience on Easter Day 1984 and became an anti-nuclear activist. And then I told everyone I could—in particular, my laboratory and discussion sections that I taught as a graduate teaching assistant—about it.

This was about the same time that Global Warming science started to get broadly noticed. While research into Global Warming was already a couple of decades old, it was not talked about very much before about 1984. Global Warming and Nuclear Winter were, therefore, both fledgling theories at that time. In case you wonder how they could both be true, it is simple: Global Warming if you don’t have nuclear war, Nuclear Winter if you do.

That’s when the two theories started to diverge. As more scientists investigated Nuclear Winter, they began to get skeptical. The numbers were a little off. Maybe that dirty-snow effect was a little more important than previously thought. Maybe the smoke and dust would settle fast enough that the Earth would not have a chance to cool off very much. The principle of Nuclear Winter was sound, but the new calculations began to show that the cooling after nuclear war would not be as profound as previously estimated. I remember that by 1986 some scientists were talking about Nuclear Autumn.  And not long after that, Nuclear Winter was just not discussed very much by scientists.

Meanwhile, the evidence for Global Warming became clearer and clearer. Not the least of the evidence was that, since the 1980s, nearly every year has been one of the hottest on record. The arctic ice really has been melting and getting thinner. The Northwest Passage really did open up. Glaciers really have retreated. Global Warming science has advanced as Nuclear Winter science has retreated.

Scientists were willing to give up the theory of Nuclear Winter, even those like me who held it with an almost gospel intensity. Scientists are also willing to give up the theory of Global Warming, should the evidence ever warrant it. I say this because scientists have in fact changed their views about a major global issue that has political consequences. But the evidence supporting Global Warming science is so massive, and of so many different kinds (temperatures, ice, tree buds, bird migrations, methane bubbles in Siberia), that this is extremely unlikely to happen. I guess it could. I guess we might even find out that the geocentrists were correct after all. And if it does turn out that Global Warming scientists, or Copernicus, were wrong, scientists will (eventually) admit it.

Oh, I forgot one little thing. The Great God Donald Trump has proclaimed that Global Warming theory was invented by the Chinese as a way of ruining our economy. Well, Trump has spoken. That takes care of that. Evidence? God doesn’t need evidence.

Our Overwhelming New Challenge: The Denial of Physical Reality

Science educators have always assumed that we will be challenged by creationists. More recently, we have been challenged by global warming denialists. Major science education associations, whether national (such as National Center forScientific Education) or local (such as Oklahomans for Excellence inScience Education), now consider it their mission to respond to both challenges.

But now the conservatives are attacking every branch of science. And they are attacking physical reality itself. This means that there is nothing that scientists can say or science educators can teach that will make any difference, since we always base our statements on physical proof.

The major example that has been in the news recently is Representative Todd Akin (R-MO) who is running as the Republican nominee for Senate. Even the Republican Party withdrew support for him when he made comments about “legitimate rape.” I am not sure whether the Republicans were all that upset about his scientific claim that a woman’s body can “shut down” a pregnancy. He apparently knows nothing about human anatomy and physiology, nor did he consider it worth his while to find out. Apparently he was satisfied with just making something up and saying it. Apparently reproductive anatomy and physiology is under attack by some conservatives.

And there are some conservatives who use biblical statements upon which to base their beliefs that the Earth is the center of the universe and does not move and that there are Methuselahs living inside the Earth.(Note: my browser indicates that the anti-Copernican website above may be unsafe to visit.) Warren Chisum, who was at one time the second most powerful Republican in the Texas House of Representatives (he is leaving office January 2013), informed some of his colleagues that the fixedearth.com website revealed important information indicating that the Copernican view might be a hoax.

I had an experience on August 31 that took me totally by surprise. I was teaching general biology, and the topic was global warming. I was presenting evidence of global warming. In a previous section of the class, I had talked about the Antarctic ice layers, and how scientists could determine global temperatures and atmospheric carbon dioxide levels from them. I was expecting, and got, a challenge about how global warming is part of a recurring cycle; I told the student that yes, indeed, it was, he was right, but I then explained how the global warming that is occurring today is different from the previous cycles of warming.

What I was not expecting, in this section, was loud criticism from two creationist students that, since the Earth is only 4,000 years old (I assume they meant since the Flood) there could not be 400,000 layers of ice in Antarctica. That would mean that 100 layers of ice would have to form every year for the last 4,000 years. This, I said, would have to be a miracle. They were unwilling to defend the idea of God doing such a deceptive miracle. The conclusion was, apparently, that I was lying about there being thousands of ice layers in Antarctica. I showed them a photograph of the ice layers that I had taken (not, of course, all 400,000 of them) but this was not good enough for the students. I suppose photos can be faked. What I had experienced was an attack on the admissibility of physical evidence itself—their religious view simply did not permit the existence of those ice layers. I was totally unable to know what to do next. Fortunately other students told the creationists that they had come to learn from me not from other students, and class went back to normal except that I could not concentrate.

These students had already challenged me earlier in the class. They said that if the atmospheric carbon dioxide readings were made in Hawaii, wouldn’t the volcanoes have messed up those measurements? This was a reasonable question and I answered it, in two ways: first, the Mauna Loa observatory is thousands of feet above current volcanic eruptions; second, the measured increase in carbon dioxide is uniform from year to year, irrespective of periods of volcanic eruption. I forgot all about this discussion until later, since it was a reasonable question. I did not become quietly upset until they attacked the existence of the 400,000 ice layers.

I think we will increasingly encounter such attacks. When we teach about the existence of human endogenous retroviruses (HERV) in our chromosomes, we can expect creationists to criticize their interpretation; but maybe we should now expect them to claim that HERV simply do not exist. Pseudogenes? Perhaps they do not exist either. If we said the Nobel Prize for Physiology or Medicine in 2004 went to the discoverers of the olfactory pseudogenes, the students will perhaps simply say that is an international scientific hoax.

Of course creationists reject radiometric dating. Uranium-lead dating is based upon the fact that zircon crystals do not incorporate lead while they are forming. Perhaps now I should expect creationists to reject the facts of chemistry and say that, in fact, zircon crystals do contain lead when they form, even though uranium atoms have seven shells with a valence of two while lead has six shells and a valence of four. How could I prove this to them? I can’t say, “I just happen to have a uranium atom here, and as you can see it has seven shells of electrons, with two on the outside.” Or, “I just happen to have a freshly-forming zircon crystal, and as you can see there are no lead atoms in it.” How should I handle this? I simply cannot prepare for every possible challenge to the reality of physical evidence. Meanwhile all creationists have to do is to say, for example, “I won’t believe that carbon atoms exist unless you prove it to me right here in the middle of class.”

There are some things I can prove to them, maybe. If they claim that photosynthesis will clean all of the additional carbon dioxide out of the air even during droughts, I can tell them I have actually measured photosynthetic rates in drought-challenged plants and drought does indeed reduce and eventually stop photosynthesis. Or maybe they would just say I am lying. What can I do?

Conservatives have become very good at reinventing reality. Lots of people consider the Republican Party to be the party of fiscal responsibility, as if the administration of George W. Bush (with a trillion-dollar deficit-funded war) had never happened. You will notice they hardly mentioned it during their convention. The only mention was by Jeb Bush, who said, “I love my brother.” Otherwise, for aught we hear from Republicans, the Republican Party was created de novo ex nihilo in 2009 in Edenic perfection.

I fear that we have a new generation of extreme conservatives coming along who do not believe in physical evidence. Truth, to them, is whatever their party or their preacher tells them, even if there is physical evidence or historical records against it. There has, perhaps, never been such a challenge to science or to science education. At least not since the clerics simply refused to look through Galileo’s telescope and see the moons of Jupiter.

Please post comments about your experiences, or suggestions about what to do.