Science Snippets: Human Activity Changes Tilt, Rotation of Earth as Arctic Mercury Bomb Poses Threat

Draft script:

That’s right: Human activity is changing the tilt and rotation of Earth. According to a headline at BBC on 20 December 2024, Human activity is changing Earth’s tilt and rotation. What does that mean for the planet? The subhead tells the tale: “Scientists have found that using underground water has more of an impact on Earth’s tilt than melting polar caps.”

The article was written by climate scientist and Professor Emeritus Bill McGuire. It begins with six paragraphs that demonstrate McGuire’s ability to teach:

“Even though we can’t feel it, most of us are aware that our planet spins like a top during its interminable journey around the Sun. Rather than revolving about a vertical axis, however, Earth has always been off-kilter, spinning about an axis (or pole of rotation) that’s tilted at 23.44°.

The amount of tilt – also known as obliquity – is never constant, and displays natural short-term oscillations and longer-term cycles.

Earth’s tilt can also be changed by shifting huge amounts of mass around the planet. And this is happening right now, on an extraordinary scale, due to us.

As global heating drives the melting of the polar ice sheets, it decants colossal volumes of water into the oceans. In a recent paper, scientists have revealed that this redistribution of mass is very slightly modifying the world’s tilt.

But there’s more. In itself, polar melting isn’t sufficient to account for all of the tilt change – something else has to be happening too. The answer, the authors of the paper say, is beneath our feet.

In recent decades, the world’s ever-growing population has resulted in a huge increase in demand for freshwater, particularly for use in crop irrigation. This need has been largely met by sucking up an estimated 23 million cubic kilometres of groundwater that was once locked away in aquifers beneath Earth’s surface.”

The article continues with another explanatory paragraph: “The authors [of the peer-reviewed study embedded in the fourth paragraph] have shown that the tilt change can be completely explained if, over the period of study, a water mass of around 2,150 billion [metric] tonnes (equal to 2,150 cubic kilometres) was abstracted from aquifers and used in one way or another, before finding its way, ultimately, into the oceans.”

The article continues with a subsection titled “We have a deeper impact than we think.”

“Should we be worried? Such a tiny change in tilt isn’t going to have an impact on the climate, so the answer should be no. On the other hand, this finding shows that how we live today has a measurable impact on a planetary scale.”

We are rapidly heating the temperature of the only planet in the universe known with certainty to support life. Deniers of anthropogenic climate change take note: In so doing, we are causing shifts in precipitation, loss of habitat for many organisms, and the worst Mass Extinction Event in planetary history. Furthermore, as explained by the article at the BBC: “In addition to modifying tilt, the redistribution of mass from polar regions into the ocean basins has also contributed towards slowing the planet’s rotation. This is estimated to be happening at 1.3 milliseconds a century.”

That doesn’t sound like much. From a human perspective, it’s barely noticeable. However, our species has come to depend on electronic systems and networks. These, in turn, depend on accurate, precise time-keeping. The BBC article continues with some examples: “the GPS that allows planes and ships to navigate, the algorithms that underpin today’s financial markets and global timekeeping.” Although we might not notice these changes in our daily lives, glitches were reported across multiple networks when a leap second was added to the world’s atomic clocks in 2015.

I mentioned the importance of GPS for contemporary life in a previous video. The article in BBC reiterates this importance, and adds other factors. “As groundwater aquifers are drained further, and polar melting continues, repeated tweaks to timekeeping and positioning systems – to account for new tilt and day length variations – will be essential to prevent their potentially catastrophic failures.”

The peer-reviewed, open-access paper mentioned in the BBC article was published in Geophysical Research Letters on 15 June 2023. Written by eight scholars, the paper is titled Drifts of Earth’s Pole Confirms Groundwater Depletion as a Significant Contributor to Global Sea Level Rise 1993-2010. After an Abstract, the paper includes two key points: (1) Earth’s pole has drifted toward 64.16°E[ast] at a speed of 4.36 cm/yr during 1993-2010 due to groundwater depletion and resulting sea level rise, and (2) Including groundwater depletion effects, the drift of Earth’s rotational pole agrees remarkably well with observations.”

It’s worse than that, of course. As we are busily ignoring Earth’s tilt and rotation, there is a rapidly ticking time bomb in the Arctic. This is not the ice-free Arctic Ocean about which I have commented previously in this space. This is a relatively new threat, that of mercury.

An article published in Phys.Org on 15 August 2024 describes this threat. It is titled ‘Mercury bomb’ threatens millions as Arctic temperatures rise, study warns. The article includes this information: “As the Arctic warms with climate change, heating up to four times faster than the global average, mercury sequestered in the permafrost for millennia is being eroded by rivers and released into the environment.

In a study published in Environmental Research Letters today [on 15 August 2024], researchers at the USC Dornsife College of Letters, Arts and Sciences introduce a more accurate method to measure the amount of mercury released from permafrost by the river and estimate the total mercury awaiting release.

The toxic metal poses an environmental and health threat to the 5 million people living in the Arctic zone, more than 3 million of whom live in areas where permafrost is expected to vanish altogether by 2050.”

The peer-reviewed, open-access paper in Environmental Research Letters was created by 12 scholars and published on 15 August 2024. Titled Mercury stocks in discontinuous permafrost and their mobilization by river migration in the Yukon River Basin, the Abstract contains this critical information: “Rapid warming in the Arctic threatens to destabilize mercury deposits contained within soils in permafrost regions. Yet current estimates of the amount of [mercury] in permafrost vary by ∼4 times. Moreover, how [mercury] will be released to the environment as permafrost thaws remains poorly known, despite threats to water quality, human health, and the environment. Here we present new measurements of total mercury (THg) contents in discontinuous permafrost in the Yukon River Basin in Alaska. … [A] significant amount of total mercury is liberated from permafrost during bank erosion, while a variable but generally lesser portion is subsequently redeposited by migrating rivers.”

Published five days later, the headline of a 20 August 2024 article at Popular Mechanics is There’s a Ticking Mercury Bomb in the Arctic. Scientists Are Racing to Defuse It. The subhead reads “As permafrost continues melting at staggering rates, the toxic metals it’s long locked away are reentering the wild.” The article begins with three key points: “(1) Permafrost covers roughly 25 percent of exposed land surface in the Northern hemisphere, and it plays a vital role in locking away carbon and toxic metals like mercury; (2) A new study says that a looming “mercury bomb” could impact northern communities as permafrost continues to thaw, releasing mercury into the local food chain; and (3) Although rivers do rebury some of this mercury into sediment, further research will be needed to understand this erosion-reburial cycle.”

The threats, existential and otherwise, are numerous. Consequences result when more than eight billion humans demand more of everything on a finite planet. A few bro-billionaires, each of them focused on accumulating more material possessions, are not helping.