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Researchers used more than 120 years of data to decipher how melting ice, dwindling groundwater, and rising seas are nudging the planet’s spin axis and lengthening days.
Days on Earth are growing slightly longer, and that change is accelerating. The reason is connected to the same mechanisms that also have caused the planet’s axis to meander by about 30 feet (10 meters) in the past 120 years. The findings come from two recent NASA-funded studies focused on how the climate-related redistribution of ice and water has affected Earth’s rotation.
This redistribution occurs when ice sheets and glaciers melt more than they grow from snowfall and when aquifers lose more groundwater than precipitation replenishes. These resulting shifts in mass cause the planet to wobble as it spins and its axis to shift location — a phenomenon called polar motion. They also cause Earth’s rotation to slow, measured by the lengthening of the day. Both have been recorded since 1900.
Analyzing polar motion across 12 decades, scientists attributed nearly all of the periodic oscillations in the axis’ position to changes in groundwater, ice sheets, glaciers, and sea levels. According to a paper published recently in Nature Geoscience, the mass variations during the 20th century mostly resulted from natural climate cycles.
The same researchers teamed on a subsequent study that focused on day length. They found that, since 2000, days have been getting longer by about 1.33 milliseconds per 100 years, a faster pace than at any point in the prior century. The cause: the accelerated melting of glaciers and the Antarctic and Greenland ice sheets due to human-caused greenhouse emissions. Their results were published July 15 in Proceedings of the National Academy of Sciences.
“The common thread between the two papers is that climate-related changes on Earth’s surface, whether human-caused or not, are strong drivers of the changes we’re seeing in the planet’s rotation,” said Surendra Adhikari, a co-author of both papers and a geophysicist at NASA’s Jet Propulsion Laboratory in Southern California.
Decades of Polar Motion
In the earliest days, scientists tracked polar motion by measuring the apparent movement of stars. They later switched to very long baseline interferometry, which analyzes radio signals from quasars, or satellite laser ranging, which points lasers at satellites.
Researchers have long surmised that polar motion results from a combination of processes in Earth’s interior and at the surface. Less clear was how much each process shifts the axis and what kind of effect each exerts — whether cyclical movements that repeat in periods from weeks to decades, or sustained drift over the course of centuries or millennia.
For their paper, researchers used machine-learning algorithms to dissect the 120-year record. They found that 90% of recurring fluctuations between 1900 and 2018 could be explained by changes in groundwater, ice sheets, glaciers, and sea level. The remainder mostly resulted from Earth’s interior dynamics, like the wobble from the tilt of the inner core with respect to the bulk of the planet.
The patterns of polar motion linked to surface mass shifts repeated a few times about every 25 years during the 20th century, suggesting to the researchers that they were largely due to natural climate variations. Past papers have drawn connections between more recent polar motion and human activities, including one authored by Adhikari that attributed a sudden eastward drift of the axis (starting around 2000) to faster melting of the Greenland and Antarctic ice sheets and groundwater depletion in Eurasia.
That research focused on the past two decades, during which groundwater and ice mass loss as well as sea level rise — all measured via satellites — have had strong connections to human-caused climate change.
“It’s true to a certain degree” that human activities factor into polar motion, said Mostafa Kiani Shahvandi, lead author of both papers and a doctoral student at the Swiss university ETH Zurich. “But there are natural modes in the climate system that have the main effect on polar motion oscillations.”
Longer Days
For the second paper, the authors used satellite observations of mass change from the GRACE mission (short for Gravity Recovery and Climate Experiment) and its follow-on GRACE-FO, as well as previous mass-balance studies that analyzed the contributions of changes in groundwater, ice sheets, and glaciers to sea level rise in the 20th century to reconstruct changes in the length of days due to those factors from 1900 to 2018.
Scientists have known through historical eclipse records that length of day has been growing for millennia. While almost imperceptible to humans, the lag must be accounted for because many modern technologies, including GPS, rely on precise timekeeping.
In recent decades, the faster melting of ice sheets has shifted mass from the poles toward the equatorial ocean. This flattening causes Earth to decelerate and the day to lengthen, similar to when an ice skater lowers and spreads their arms to slow a spin.
The authors noticed an uptick just after 2000 in how fast the day was lengthening, a change closely correlated with independent observations of the flattening. For the period from 2000 to 2018, the rate of length-of-day increase due to movement of ice and groundwater was 1.33 milliseconds per century — faster than at any period in the prior 100 years, when it varied from 0.3 to 1.0 milliseconds per century.
The lengthening due to ice and groundwater changes could decelerate by 2100 under a climate scenario of severely reduced emissions, the researchers note. (Even if emissions were to stop today, previously released gases — particularly carbon dioxide — would linger for decades longer.)
If emissions continue to rise, lengthening of day from climate change could reach as high as 2.62 milliseconds per century, overtaking the effect of the Moon’s pull on tides, which has been increasing Earth’s length of day by 2.4 milliseconds per century, on average. Called lunar tidal friction, the effect has been the primary cause of Earth’s day-length increase for billions for years.
“In barely 100 years, human beings have altered the climate system to such a degree that we’re seeing the impact on the very way the planet spins,” Adhikari said.
Article by NASA and the National Jet Propulsion Laboratory.
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It should be noted also that the Magnetic North Pole has been shifting westward about 40 KM a year towards Russia. The poles have switched, N to S and is predicted to happen again. This is without Global warming, climate change etc. Being a pilot, the aeronautical charts have been updated from time to time. I use the sectional charts for navigation. The Earth is a living body, always changing and breathing.
Milankovitch Cycles.
So, in other words, climate change is a self-reinforcing phenomena? It makes perfect sense.
Carbon Dioxide follows because there is now more land mass covered with life. And death, which causes the decomposition of organics and therefore increased CO2. This is a good thing because it means there is life going on, and that feeds on itself, causing more life. This increased life is caused by climate change, not the other way around.
The Earth’s natural carbon footprint is orders of magnitude larger than mankind’s. Sorry to hurt your ego’s 😉
Was in Boston last weekend. According to these goofballs it should be underwater by now. Instead the sea levels are where they were 100 years ago.
Climate Change is a hoax. Now let’s talk about the effect of chemtrails…..
Using the number of 1 millisecond per 100 years, it will take 100,000 years to make a 1 second change. Let’s use taxpayer money wisely.
Curiously, not one mention of the Milankovitch Cycles. Climate change isn’t changing the earth’s rotation. Changes in the earth’s rotation and its orbit around the sun are changing the climate. This contradiction is poignant. In February 2020, the NASA Science Editorial Team published an article titled Milankovitch (Orbital) Cycles and Their Role in Earth’s Climate.
https://science.nasa.gov/science-research/earth-science/milankovitch-orbital-cycles-and-their-role-in-earths-climate/
Read about ‘precession’. The earth’s axis is moving in a circle. In fact, 13,000 years ago, the earth’s axis tilt was reversed, causing more warming, and the beginning of the end of the most recent ice age. We’re still in that cycle. Further, the tilt of the earth’s axis is 23.5 degrees. But every 41,000 the tilt cycles too. I suggest everyone read about the Milankovitch cycles.
https://www.youtube.com/watch?v=iA788usYNWA
Why the contradiction in NASA’s current missive compared to its 2020 NASA article? Conspiracy theories? Don’t get me started. Suffice it to say, CO2 is not the problem!
Strange… one VDC commentor (we all know who he is) thinks this is all a conspiracy theory. Go figure.
https://vermontdailychronicle.com/hospital-state-government-lose-internet-to-crowdstrike-outage/comment-page-1/#comment-72269
Curiously, not one mention of the Milankovitch Cycles. Climate change isn’t changing the earth’s rotation. Changes in the earth’s rotation and its orbit around the sun are changing the climate. This contradiction is poignant. In February 2020, the NASA Science Editorial Team published an article titled Milankovitch (Orbital) Cycles and Their Role in Earth’s Climate.
https://science.nasa.gov/science-research/earth-science/milankovitch-orbital-cycles-and-their-role-in-earths-climate/
Check out ‘precession’. The earth’s axis is moving in a circle. In fact, 13,000 years ago, the earth’s axis tilt was reversed, causing more warming, and the beginning of the end of the most recent ice age. We’re still in that cycle. Further, the tilt of the earth’s axis is 23.5 degrees. But every 41,000 years the tilt cycles too. I suggest everyone read about the Milankovitch cycles.
Why the contradiction in NASA’s current missive compared to its 2020 NASA article? Conspiracy theories? Don’t get me started. Suffice it to say, CO2 is not the problem!
Several reasons. Firstly, we allow many viewpoints to have a voice, rather than promote a singular narrative. The data may have, over 4 years of new study, shown new things. Also, the articles by “NASA” are really written by a number of different people, each with different perspectives, and the different articles can easily reflect that. In addition, there are different amounts of funding based on politicizing issues found in every governmental organization, no matter what party is at the helm.
Science progresses because we can approach things from different angles, and find better ways to model our universe and see if predictions match up with our ideas. One study doesn’t equal definitive proof of anything, though, and more need to be conducted to see if they match up.
Timothy Page: The study of climate change has been ongoing for centuries, if not millennia. The Milankovitch cycles have withstood the test of time for 100 years now. A NASA reversal of opinion over a mere four-year period (the last four years, in fact) is not explained because ‘science progresses’. Unless, of course, we’re prone to believe that Covid 19 came from a Chinese wet-market, that gain-of function research never occurred, that Joe Biden was ‘at the top of his game’, or “…that artificial sweeteners were safe, WMDs were in Iraq, and Anna Nicole married for love.”
NASA – a budget of over $24 billion with over 18,000 employees, established in 1958.
“Operation Paperclip was a secret United States intelligence program in which more than 1,600 German scientists, engineers, and technicians were taken from former Nazi Germany to the U.S. for government employment after the end of World War II in Europe, between 1945–59. Some were former members and leaders of the Nazi Party.
The effort began in earnest in 1945, as the Allies advanced into Germany and discovered a wealth of scientific talent and advanced research that had contributed to Germany’s wartime technological advancements. The U.S. Joint Chiefs of Staff officially established Operation Overcast on July 20, 1945, with the dual aim of leveraging German expertise to assist in the ongoing war effort against Japan, and to bolster U.S. postwar military research. The Operation was conducted by the Joint Intelligence Objectives Agency (JIOA), which was largely carried out by special agents of the U.S. Army’s Counterintelligence Corps (CIC). Scientists taken were often involved in the Nazi rocket program, aviation, and chemical and biological warfare.
The operation was characterized by the recruitment of German specialists, along with their families, bringing the total to more than 6,000 relocated to the US for their expertise, valued at US$10 billion in patents and industrial processes. These recruits included notable figures such as Wernher von Braun, a leading scientist in rocket technology, and were instrumental in the development of the U.S. space program and military technology during the Cold War. Despite its contributions to American scientific advances, Operation Paperclip has been controversial due to the Nazi affiliations of many recruits, and the ethical implications of assimilating individuals associated with war crimes into American society.”
There is no business like show business.
Curiously, not one mention of the Milankovitch Cycles in this missive. Climate change isn’t changing the earth’s rotation. Changes in the earth’s rotation and its orbit around the sun are changing the climate. This contradiction is poignant. In February 2020, the NASA Science Editorial Team published an article titled Milankovitch (Orbital) Cycles and Their Role in Earth’s Climate. Why no mention today?
Read about ‘precession’. The earth’s axis is moving in a circle. In fact, 13,000 years ago, the earth’s axis tilt was reversed, causing more warming, and the beginning of the end of the most recent ice age. We’re still in that cycle. Further, the tilt of the earth’s axis is 23.5 degrees. But every 41,000 years the tilt cycles too. I suggest everyone read about the Milankovitch cycles.
Why the contradiction in NASA’s current missive compared to its 2020 NASA article? Conspiracy theories? Don’t get me started. Suffice it to say, CO2 is not the problem!
Follow-up criticism to this article:
“That research focused on the past two decades, during which groundwater and ice mass loss as well as sea level rise — all measured via satellites — have had strong connections to human-caused climate change.”
This statement pre-supposes that human activity causes climate change, and is an example of circular reasoning.
In the following paragraph: ““It’s true to a certain degree” that human activities factor into polar motion, said Mostafa Kiani Shahvandi, lead author of both papers and a doctoral student at the Swiss university ETH Zurich.”
Again, the doctoral student is making a claim that is not supported by the research at hand, that “It’s true that human activities factor into polar motion”. She is again using circular reasoning, claiming “A is true because A is true”. This is a propaganda/advertising technique used to convince the consumer of the product’s credibility.
“In barely 100 years, human beings have altered the climate system to such a degree that we’re seeing the impact on the very way the planet spins,” Adhikari said.
The jump from the observations of changes to the Earth’s axis to assigning human activity as the cause is not supported. Even if the measurements are accurate, there is only a tentative correlation demonstrated. One could just as easily argue that the change in axis caused the change in water/ice distribution. The authors also do not compare the mass redistribution of the water/ice to the mass redistribution of volcanic activity. For example, the the Lava Creek eruption at Yellowstone approximately 640,000 years ago redistributed 275 Cubic Miles of solid earth and rock.
It does not appear that this paper or the ones cited have been properly peer-reviewed, and they are most likely being promoted for political reasons. That said, the research being done is interesting and worthy of publication. However, the authors desperately need to remove their personal opinions and feelings from their publication and limit their remarks to the observations they made.
Mr. Eshelman’s comments and link (above) to the NASA website about Milankovitch Cycles is very well worth reading. That theory has withstood the test of time and scrutiny. Observations from multiple sources match that theory.