Chelsea Harvey in reported in the Washington Post: “Rising global temperatures may be affecting the Greenland ice sheet — and its contribution to sea-level rise — in more serious ways tha[n] scientists imagined, a new study finds.” What’s up with this?

The concern is about the “firn”—a porous sheet of snow that slowly freezes into ice over time as more and more snow accumulates atop it but can absorb melt water in the meantime. According to the study, a layer of ice several meters thick has developed on top of the firn. Consequently, when surface snow or ice melts, the meltwater can’t seep into the porous snow but must instead run off into the sea, increasing the rate of loss of the Greenland ice cap and speeding sea level rise.

Conceptually, it’s simple. Imagine that you have a dry or semi-dry sponge, and you pour water onto it. Some, maybe all, of the water will be absorbed. But if you put a sheet of solid plastic over the sponge and then pour water on it, the water can’t reach the sponge and so runs off the sides instead.

So conceptually there’s nothing wrong with the idea. The problem is historical.

What’s wrong with the history here?

The Washington Post report and the study both failed to notice that the ice atop the firn didn’t come from long-term climate change but from short-term weather.

How do I know that?

One thing the study found was that “An extreme melt that occurred in 2012 caused a layer of solid ice, several metres thick, to form on top of the porous firn in the low elevation areas of the ice sheet.” Yet one of the study’s authors also said, and I quote, “Basically our research shows that the firn reacts fast to a changing climate. Its ability to limit mass loss of the ice sheet by retaining meltwater could be smaller than previously assumed.”

But in reality, as Anthony Watts pointed out in WattsUpwithThat.com shortly after the study appeared, the glacial melt and the consequent formation of the ice atop the firn were not the result of long-term climate change, whether natural or manmade. How do I know that? For two reasons.

First, because they were, as the study itself recognized, the result of a single weather event in 2012, in which a combination of warm weather—weather, that’s short-term, not climate, which is long-term—and black soot from forest fires in Canada speeded glacial melt for a short time, not long-term climate change.

And second, that brief period of warm weather of Greenland in 2012 was not the result of long-term climate change. Why? Because as of 2012 there had been no global warming for over fifteen years (and now almost nineteen)—which raises the question, if it was as warm in each of the previous fifteen years, why didn’t the glacial melt and ice layer atop the firn form in any of those years instead?

So in short, there’s no tie here to global warming, whether manmade or natural.