The Earth’s Wobble is Veering


The earth, minding its own business, while secretly wobbling on its axis. Photo by kajmeister.

It doesn’t take much to get me going down a rabbit hole for facts. I’m on the hunt now, I’m on the trail. Harper’s published a factoid in their current issue’s Index which said:

Distance, in feet, by which the Earth’s axis of spin has shifted since 1899: 34
Estimated percentage of that shift that is due to climate change: 40
Harper’s Index, Dec 2018

Thirty-four feet? Really? How do they know that?  I do understand that climate change is occurring, however I also like to understand the facts behind statements. How do they know it’s due to climate change?

Start With the Wobble

First, we have to visualize the earth spinning on an axis and having a wobble.

The Wobble Dance
Dance “The Wobble”

No, not that kind of Wobble.

Start with the earth. It leans. What does lean mean? It is a matter of perspective. For example, many of us have been brought up to believe that north is up:

World Map, north at top
Standard world map from

But, in fact, there’s no reason to view the world that way. People who happen to be standing in Antarctica don’t stand on their heads. From their point of view, the world map would look like this:

World Map, south at top
World Map, southern orientation. From

North is not “up” any more than south is, and the earth’s tilt is relative. If you were in space, the earth wouldn’t particularly look tilted; there’s no “up”in space, right? Perspective is what we’re talking about.

The earth tilts relative to the plane of its orbit around the sun. It tilts because of how it was formed relative to all the other gravitational-influencing matter in the solar system (i.e. Sun and planets). That tilt gives us the seasons, which I’ve written about it before. The globe spins on this axis of rotation at a tilt compared to the ellipses of its journey around the sun. OK, you know all about that, at least you think so… Did you also know that the entire solar system oscillates in ITS rotation in and out of the Sagittarius arm of the Milky Way such that the system goes through the densest part about every 20 million years, meaning about every 20 million years there’s a significant increase in possibility that an asteroid will hit us, wiping out most of life on earth, which has probably already happened at least twice?

Yeah, I didn’t think you knew that part.  (Track down James Powell’s Night Comes to the Cretaceous for the details.)

Spinning and Wobbling like a Top

Anyway, the axis of the earth is the imaginary line around which it spins. That spin is not “perfect” because the earth isn’t perfectly round. It bulges at the equator a little and has moving things on it, namely a lot of water, as well as moving things under the crust, like molten rock.

As a toddler, my favorite toy was one of those tops where you pushed the handle to make it spin.  The spin comes from the interplay of force, angular momentum, and torque. The wobble, as the top slows down, is due to precession and nutation. Try to understand those terms further, though, and you run into lots of Greek symbols and offhand physics jokes that only physicists understand like:

Using this law, which is strictly for motion in a line, we can derive what would happen for rotation. We can do this in two ways—either we hand wave and just cross product both sides with position, or we can really be detailed and check what every little bit of material is going to do and integrate over.
–“The Physics of a Spinning Top,”

I’m sure that part about the “hand wave” would give my graduate student son the giggles. I kind of prefer scientists to be really detailed. For now, let’s just there’s physics-y stuff that causes the top to stay spinning, and makes it shift when the force lessens, like if the top slows down or if some part of its weight shifts, like water on its surface.

Wobbling from the Ice Age Hangover and Greenland

The earth’s spin wobbles, not like a top which is slowing, but like one that has moving masses on it, namely all the water and crust and ice. Scientists looking at the previous century determined that the spin axis was drifting about four inches a year, 33 feet between 1900 and 2000. The drift was towards Canada, due to a combination of glacial rebound, meaning the continued readjustment to loss of ice in North America after the last Ice Age, 12,000 years ago, and mantle convection.  That’s the molten rock moving around at the center of the earth, which according to several movies is near lost dinosaurs, carnivorous plants, and diamonds, although I don’t think those contribute to the wobble.

Meanwhile, around the year 2000, scientists noticed that the direction of the wobble had changed.  Depending on who you read, this might be treated as fascinating or alarming:

TAKE A LOOK!!… EARTH POLE has again moved to new uncharted area…THE GLOBAL ELITE SEEM TO [BE] REMOVING THEMSELVES FROM THE PUBLIC EYE! Earth Pole Rotation Being Affected by Outside Planetary Influence [solar affects]…–

That particular site also explains how cold fusion powderized the Twin Towers and includes pictures of a “Huge earth crack…opening up in Pakistan…” So, we might want to stick with sources like JPL (Jet Propulsion Lab/NASA), which is where Harper’s started.

According to NASA, the biggest driver of the new change in the wobble is not the Illuminati or Mindhead but the melting of Greenland and the Antarctic ice shelf. JPL was even able to calculate how much of the shift away from Canada and towards the British Isles was due to the melt vs. “normal” molten lava and glacial movement.

NASA photos of the earth
NASA: The wobble shifts toward the UK.

Not So Fact-y Facts

Like some of the bloggers, not all the writers on this phenomenon get the facts straight. One article, for instance, from The Weather Channel said [I’m paraphrasing] Greenland’s ice melting due to climate change is causing the earth to wobble which is why your GPS makes you get lost.  Ominous music plays as a video of Greenland, satellites, and confused drivers wash across the screen. But that’s not right.

Greenland, Siberia, and Antarctica’s ice melting due to climate change are collectively shifting the way the earth wobbles, so that instead of wobbling westerly to Canada, it’s easterly towards the British Isles.  Even Harper’s had it a little wrong. The spin shifted 33 feet in the 20th century from mantle convection and leftover effects from the Ice Age, before climate change. Now the spin shift is moving in a different direction, and 40% of that change can be accounted for by climate change.

Let’s get our dire climate change facts correct, people!

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