Friday, September 7, 2007

sceptics after a scientific revolution: global warming and plate tectonics

I wish I could remember where I read this criticism of An Inconvenient Truth, but I don't, so I'll have to paraphrase it.

[Edit: yorrike commented with the reference I was thinking of: Geek Counterpoint, at, said:

Metaphor -- fit of South American & African coastlines, difficulties that plate tectonics / "continental drift" had in being accepted.

Comment: This is a really lousy choice of metaphor. The theory of "continental drift" had a tough fight being accepted because it took decades to find data that explained how it worked. Once the data was available, though, the scientific community came around very quickly.

The rest of the post will read weird now, but I'll leave it as it is.]

Near the beginning of the movie, Al Gore tells a story about an old science teacher he once had. According to the story, someone asked the teacher about the similarities of the coastlines of South America and Africa, and asked whether they could ever have fit together. The teacher said no.

The story was told as a lesson that scientists can change their minds. It's also used as a parallel to discussions of anthropogenic global warming, to suggest that a scientific revolution has already occurred. (Science historian Naomi Oreskes, who has studied both the development of plate tectonics and the debate over global warming, has made that point. There are links to her work at the end of the Stranger Fruit post.)

Anyway, I chuckled at the plate tectonics reference in An Inconvenient Truth, and found it pretty appropriate. But I read a comment recently that took issue with it.

The argument went that plate tectonics was accepted quickly, after the data to support the theory built up. There are still skeptics about global warming. So the parallel must be inappropriate.

But, well... I think that geologists have been telling the story of the development of plate tectonics a bit too well. Now, I'm too young to have been at that pivotal AGU meeting where the pieces are said to have fallen into place. But I'm not too young to have encountered skeptics, even decades after the theory was accepted. One of them retired from my current institution less than a decade ago; recent alums still want answers to his questions.

And he wasn't alone - in fact, some very prominent geoscientists, people whose data and ideas contributed to the development of plate tectonics, remained skeptical until their deaths.

I can't find anything online that says this, but none other than Maurice "Doc" Ewing, founder of the Lamont Geological Observatory, supposedly remained skeptical about plate tectonics until his death in 1974. And that's despite being responsible for the amazing exploration of the ocean floor that was responsible for the revolution. (I'm pretty sure that this story comes up at some point in Naomi Oreskes' book Plate Tectonics; if it doesn't, I've heard it repeated by Lamont alums.) That's right. Plate tectonics was developed using data collected by Doc Ewing's researchers, but Ewing himself never accepted it.

S. Warren Carey was a much more obvious skeptic. He worked on the problem of mid-ocean ridges soon after they were recognized, and he argued that they were the result of spreading of the ocean floor. That was an amazing contribution to the science, and he was awarded a GSA Structure/Tectonics Career Contribution Award in 2000 for that and other work. But he never believed that subduction occurred - he argued that the earth was expanding, and that subduction zones were actually zones of extension. (There are some pretty pesky focal mechanisms to explain, and there's the problem of how that magma gets to the surface.) He wrote about "diapiric krikogenesis" as an alternative explanation for arcs, as late as the 1980's.

Those two examples were people who did ground-breaking work in the field. I'm pretty sure there are others. The pioneers of plate tectonics are retiring now, and the skeptics are passing away, and the stories that we tell introductory students begin to seem like ancient history. So much like ancient history that students (and members of the general public) can't imagine a debate ever occurring. And now students and others look at things like the AAPG statement on climate change and think that it means that the science is not settled - that settled science means that there are no disagreements, no mutterings about this or that hole in the theory. But the continued existence of skeptics doesn't mean that. It just means that it's hard to change the minds of people who were taught the old stuff. That the continents are fixed. That the climate has always changed and therefore all climate change is natural.

On the morning of Halloween, GSA is having a symposium on the causes of global warming. The issue seems to have been settled at AGU for years. It will interesting to see whether the GSA symposium feels like settled science (and a discussion of policy alternatives), or whether the debate at GSA continues.


Yorrike said...

The review of An Inconvenient Truth was at Geek Counterpoint, at the following address:

Kim said...

Thank you! That was exactly the one that got me thinking.