The Climate in Emergency

A weekly blog on science, news, and ideas related to climate change


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The Fog of…Fog

The other day, I went on a walk with my friend and teacher, Tom Wessels, whose name has appeared many times in this blog because he is an actual expert whose authority I can legitimately cite, and because he so consistently tells me things worth citing.

This walk was no exception.

We chatted about all sorts of things, scientific and otherwise, and generally had a good time. Other than the walk itself—we were trying to get to a particular place and explore it—we had no agenda. I’m not going to tell you all about that conversation, though much of it would interest you. I am going to tell you what he said about climate change.

Question: What Is About to Change?

In the course of our walk I asked “What is likely to change here [on Mount Dessert Island] over the next few decades, other than trees getting bigger and so forth?”

He’d already told me about the impending loss of paper birch, so he mentioned that again only in passing. He also discussed the problems of spruces, another previously discussed topic, elaborating this time that the island isn’t about to lose its spruces, but their life expectancy is being cut from 400 years to less than 100, for reasons he does not entirely understand, but climate change is likely involved as contributing stress, since they are cold-climate trees. Something is causing them to rot.

Then he told me something I did not know at all, but should have: that Mount Dessert Island is on track to lose its fogs. Not all its foggy days, perhaps, but many of them. The island will no longer be characterized by frequent fogs.

I should have known it because I knew both pieces of information that he cited as evidence. I knew that we get so much fog here because the Gulf of Maine is very cold, and I also knew that the Gulf of Maine is getting rapidly warmer. Therefore….

The Problem with the Loss of Fog

I like fog. It’s spooky and mysterious and lovely. I don’t want there to be less of it around here. But aesthetics are not the primary reason why the loss of fog would be a problem, and I didn’t need Tom to tell me what the real problem was—or, rather, I didn’t need him to tell me just then. I already knew about the ecological importance of fog around here, and I knew because he told me the better part of a decade ago.

The thing is, Mt. Dessert Island owes much of its identity to fog. A large number of natural history questions around here can be answered the same way; “because it’s so foggy.”

Most dramatically, frequent fogs allow the lichens on trees to grow much faster than they otherwise would—lichens can only grow when they’re wet, and those on bark, as opposed to soil, dry out quickly. Fog keeps them wet. And so here lichen growth is responsible for 40% of the forest’s overall nutrient balance. Less fog = less lichen = an impoverished forest.

Northern white cedar, one of the lovelier trees on the island, is also here because of fog. It requires calcium-rich soil, which our mostly granite bedrock would normally preclude, but fog motes each contain a speck of dust, and a cloud of fog contains a lot of motes and therefore a lot of dust. All that dust enriches the soil with calcium. Northern white cedar is, in fact, especially good at catching fog. I asked Tom if the cedars would be hurt by the loss of fog, and he said they might well be.

He said the fog problem will be apparent within the next fifty years, which is not a lot of time as such things go.

The Problem with Foggy Losses

As I said, I had overlooked the possibility that fog frequency could be altered as part of climate change. I’m not sure why. I’ve never before heard anyone else raise the issue, but I don’t know why I didn’t draw the conclusion myself.

What I’m wondering now is what else does climate change hold in store that nobody is talking about and that I don’t guess?

Even worse, is fog frequency already changing—without anyone talking about it?

I didn’t ask Tom. I could, but he doesn’t actually know everything, and it’s possible no one has yet crunched the relevant numbers. He is familiar with the island and its fogginess, but human beings are notoriously bad at assessing these types of trends, that’s why we invented statistics. It’s just not the sort of change we can reliably eyeball.

He said the change would be apparent within fifty years, but what does “apparent” mean? Is that when fog lessens enough to make a difference, or is that when the forests’ response to the loss becomes evident to casual human observation? If the latter, the fog might already be changing—both lichens and northern white cedars grow very slowly. Were their growth to slow even more, the difference would take a long time to add up.

How long? I don’t know. Maybe close to fifty years?

Question: What’s Changing Now?

One of the more disconcerting discoveries I made when I became an adult was that there were important topics where I was dangerously ignorant but had thought myself well-educated. I had heard simplified descriptions created for teens or as public talking points, and they had given me a clear picture of the situation with no apparent holes or gaps. So I had thought there were no gaps. I thought I knew all I needed to.

There were holes and gaps, of course, I had just been unintentionally misled by the skill with which the introductory talking points were constructed.

Simplified explanations are not bad. If well-constructed, they cover most of the important points of the subject in question while being accessible enough to reach beginners whose attention may be elsewhere. The important thing is to recognize them as simplifications. As I wrote last week, much of what most of us know about climate change is correct, but it’s simplified.

There are important things happening that we don’t always see.