Another nasty outcome of global warming is a wobble in the moon’s orbit. Which might seem even less convincing than the supposed wobble in the jet stream. But with floods in the news, we’re told the moon’s behaviour will cause horrific flooding due to climate change. Because all bad things are… need we say it again?
It looks that way. The Climate Alarm Network formerly known as the Weather Network blares that “Moon’s ‘wobble’ to amplify coastal flooding due to climate change, says NASA”. And CTV, quick to spot the Canadian angle in a mudslide, warns of “What the moon’s ‘wobble’ could mean for coastal communities in Canada” and explains that “A NASA study suggests that climate change’s impact on rising sea levels will only be amplified by the moon’s gravitational pull causing persistent high tides.”
Now look. Sea levels are rising. They have been since the end of the last glaciation, rapidly at first and then slowly.
A reader points out to us that CTV rather mangled the facts on tides. The story said “High tides occur when the moon’s gravity is pulling the water closer to it, and low tides occur when the Earth’s gravity is pulling the water down. While the areas of the Earth directly beneath the moon may be experiencing high tides, the sides of the Earth, which further away from the moon’s gravitational pull, won’t.” And while it added “But it’s not quite that simple” it didn’t understand why and started talking about the shape of coastlines and of currents.
In fact, our reader writes, “High tides occur on the side facing the moon (the sublunar side), AND on the side opposite (the antipodal side). Low tides occur perpendicular to the earth-moon alignment.” And, again, he points out that this information is not hard to find online, for instance in Wikipedia. Of course the journalist is … drum roll please… not a climate scientist. On the contrary, she has a Master’s of Journalism from Ryerson with a focus on “social justice issues” and a BA “with a major in cultural studies”. So with a world to save perhaps she’s a bit too busy to get into boring gravity/tide details.
On the other hand, the Weather Network author is a meteorologist. Who asserts that “Coastal communities are already dealing with higher tides due to sea level rise from climate change.” To which we say “Bosh”. Even if one accepts the somewhat dubious claims that sea level rise has accelerated recently, and we don’t, because it’s currently happening about as fast as it did between about 1920 and 1950 (see p. 4 here) and we don’t like those built-in data “adjustments” to hustle it along, it’s still important to ask how much it has risen due to climate change. If, say, 2 mm/year is natural and now it’s 3 where you live (in fact the pattern is very complex), then you only get to blame the extra 1 mm on climate change. And only since it started to accelerate. And how much worse can flooding be if, over the last decade, average levels went up 1 cm more than would otherwise have happened?
Seriously. That’s a tiny amount. Why, wobbles in the moon’s orbit would matter more. To say nothing of natural variations in tides. “Still,” the Weather Network insists, “a new study says that — under the influence of the Moon’s gravitational pull — this will get much worse by the mid-2030s.” Much worse.
If you can count, and not all journalists appear capable of it, you might notice that with an 18.6-year wobble cycle, the moon is currently in… hang on… mid-2030s minus 18.6 equals… 2017 or so. As the NASA study authors say “The Moon is in the tide-amplifying part of its cycle now.” So such floods are happening now. Why weren’t we told we’re under water? (Or that if we are, it’s as much the moon as the climate.) It is important.
Ah, says the Weather Network. Right now “sea level rise is only adding a small amount. After another 10–15 years of further sea level rise due to climate change, however, the next period of tidal amplification by the lunar cycle is expected to be much worse.”
Back to the calculator. How long has climate change been worsening sea level rise? When did man-made warming kick in? Help us out here, guys. We’re trying to figure out why terrible flooding will happen with an extra cm but hasn’t with whatever already did us in, brought down that Florida condo and so on. Assuming, of course, that as with weather generally, a natural sea level rise would be easy to deal with and a man-made one an unspeakable catastrophe.