Science: Fact vs. Inference

A set of scientific facts rockets across the internet. One highly respected news organization appears to cite it as a warning about global warming. But another appears to cite it to raise doubts about such warnings.

How can that be possible? It’s tempting to assume that one of these organizations must be engaged in the practice of “fake news.” A single set of facts cannot simultaneously support a pair of perfectly contradictory inferences, can it?

In reality, it can. And given that the phenomenon of global warming impacts the future of our planet, it might be helpful to take a moment to understand the difference between scientific fact and scientific inference.

The facts in question involve a gigantic crack in a region of the Antarctic ice shelf known as Larsen C. Environmental scientists have long warned that global warming would cause the collapse and melting of the shelf, generating massive increases in sea levels. Just yesterday, the New York Times reported that:

A rapidly advancing crack in Antarctica’s fourth-largest ice shelf has scientists concerned that it is getting close to a full break. The rift has accelerated this year in an area already vulnerable to warming temperatures. Since December, the crack has grown by the length of about five football fields each day.

But three weeks ago, National Public Radio reported that:

“A lot of things are going on deep inside the ice,” says Adrian Luckman, a glaciologist (who is) leading a project to track changes in the ice shelf. “This is probably not directly attributable to any warming in the region, although of course the warming won’t have helped … it’s probably just simply a natural event that’s just been waiting around to happen.”

Let’s think about the discrepancy in these news reports. At first glance, the Times appears to attribute the crack to global warming, and NPR appears to disagree with that attribution. But are the two organizations fully at odds with each other?

Not really. In reality, the authors are largely in agreement on the facts. Neither one concludes that the crack was directly caused by global warming. And neither one asserts that global warming had no impact whatsoever on the crack.

Furthermore, both authors concur that the region is warming. The Times reporter states that the area is “already vulnerable to warming temperatures.” And the NPR reporter quotes a glaciologist who agrees that “of course the warming won’t have helped.”

In other words, according to both authors, the Antarctic region is heating up and the Larsen C region is cracking. Neither concludes that the heat directly caused the cracking. They agree that other factors likely contributed to the situation. And yet they also believe that warming temperatures can’t possibly be beneficial for the stability of this gigantic chunk of ice.

Are the authors inclined to draw different inferences from the twin facts of warming temperatures and cracking ice? Sure. The Times author appears to be much more inclined to interpret the set of facts as supportive of concerns about global warming.

And yet, do they disagree on the underlying set of facts itself? Not at all.

It’s certainly reasonable to feel a bit distressed when reporters at two highly respected news organizations draw radically different inferences from a common set of facts. It’s only natural to hope that a pair of rational individuals could follow a common trail and arrive at the same destination.

But at least it’s comforting that these two reporters only differ on their inferences while agreeing on their facts. As long as we keep this scientific distinction in mind, we’ll be able to maintain our faith in science itself.