Хүн төрөлхтний хувьд 24 цаг бол хувиршгүй тогтмол мэт санагддаг ч шинжлэх ухааны үүднээс дэлхий улам бүр удаан эргэдэг болж байна. Хэдийгээр өдөр 25 цаг болох мөч ойролцоогоор 200 сая жилийн дараа тохиох боловч сүүлийн үеийн судалгаанууд энэхүү процесс бидний төсөөлснөөс өөрөөр, тэр дундаа уур амьсгалын өөрчлөлтөөс хамааралтайгаар өөрчлөгдөж байгааг анхааруулж байна. 2000 оноос хойш дэлхийн эргэлтийн мөчлөг жилд 1.33 миллисекундээр удааширч байгаа нь Гренланд болон Антарктидын мөсөн бүрхэвчний хурдан хайлтаас үүдэлтэй масс шилжилттэй шууд холбоотой болохыг NASA болон ETH Zurich-ийн судлаачид тогтоожээ.
Дэлхийн эргэлтийг сүүлийн 4.5 тэрбум жилийн турш сарны таталцал үндсэнд нь хянаж ирсэн. Сарны таталцлын нөлөөгөөр үүсдэг далайн түрлэг нь далайн ёроолтой үрэлт үүсгэж, эргэлтийг жилд 2.4 миллисекундээр удаашруулдаг байна. Гэвч орчин үеийн уур амьсгалын өөрчлөлт энэ байгалийн хэмнэлд хүчтэй нөлөөлж эхэллээ. Туйлын мөс хайлж, үүссэн ус нь экватор руу шилжих үед дэлхийн хэлбэр бага зэрэг “тэгширч”, төв хэсгээрээ масс нь нэмэгддэг. Энэ нь гараа алдалсан уран гулгагч эргэлтээ удаашруулдагтай адил физикийн зарчим юм. 2100 он гэхэд мөсөн хайлтаас үүдэлтэй удаашрал жилд 2.62 миллисекундэд хүрч, сарны нөлөөг давж гарахаар байгаа нь дэлхийн цаг хугацаа анх удаа сансрын бус, хүний хүчин зүйлээс хамаарахыг харуулж байна.
Дэлхийн эргэлтийн энэхүү өчүүхэн мэт өөрчлөлт нь орчин үеийн технологи, тэр дундаа GPS систем, харилцаа холбоо, сансрын нислэгт ашиглагддаг атом цагуудад том алдаа үүсгэх эрсдэлтэй. Тиймээс эрдэмтэд цаг хугацааны нарийвчлалыг хадгалахын тулд “нэмэлт секунд”-ийг (leap second) ашигладаг. Хүн төрөлхтний үйл ажиллагаа зөвхөн агаарын температур бус, бүхэл бүтэн гаригийн эргэлтийн хурд болон тэнхлэгт хүртэл нөлөөлж эхэлсэн нь цаг уурын хямрал ямар гүн хэмжээнд хүрснийг илтгэж буй хэрэг юм.
Эх сурвалж: Nature Geoscience and PNAS Research Archive 2026.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
If you clicked on that headline hoping to sleep in an extra hour next Monday, you can relax. The 25-hour day is coming, but the date is roughly 200 million years from now. You have time to adjust your alarm clock.
The real story hidden beneath the viral headline is more immediate and more unsettling. Since the year 2000, the familiar 24-hour cycle has been stretching at a rate of 1.33 milliseconds per century. The reason has little to do with the Moon’s ancient gravitational pull. The new force slowing Earth’s spin is the accelerating melt of ice sheets in Greenland and Antarctica.
“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,” said Surendra Adhikari, a geophysicist at NASA’s Jet Propulsion Laboratory and co-author of the recent findings.
The Moon Is Losing Its Grip on the Clock
For 4.5 billion years, Earth’s rotation has been governed by a simple gravitational tug-of-war with the Moon. The Moon’s pull creates tidal bulges in the oceans. As Earth spins beneath those bulges, friction with the seafloor acts like a persistent brake pad. According to a detailed explainer from NASA’s Goddard Space Flight Center, this process steals rotational energy and slows the planet by roughly 2.4 milliseconds per century.
That rate is so slow that it will take two hundred million years to add a single hour to the day. There is no calendar date to circle. The 25-hour day is a geological certainty, not a scheduling conflict.
But that ancient, predictable rhythm is being disrupted. Researchers led by Mostafa Kiani Shahvandi of ETH Zurich analyzed more than 120 years of data and found that climate-driven mass shifts are now accelerating the slowdown beyond what the Moon alone can explain.
Melting Ice Is Flattening the Planet
Between 2000 and 2018, the lengthening of day attributed specifically to melting ice and groundwater depletion reached 1.33 milliseconds per century. In the prior hundred years, that same contribution never exceeded 1.0 millisecond per century. The full findings are detailed in a NASA Earth science report published in July 2024.
The physics is intuitive. When the massive ice sheets of Greenland and Antarctica melt, the water does not stay at the poles. It flows into the equatorial ocean. This redistributes mass toward Earth’s midsection, flattening the planet’s shape by a tiny but measurable amount. A flatter sphere spins more slowly. The principle is identical to an ice skater extending their arms to reduce their rotation speed.
The research team relied on satellite data from NASA’s GRACE mission and its follow-on GRACE-FO to measure these mass changes with precision. They combined those observations with historical mass-balance studies to reconstruct the trend back to 1900.
The conclusion is stark. If greenhouse emissions continue to rise along current trajectories, the climate-driven lengthening of day could reach 2.62 milliseconds per century by the year 2100. At that point, human-driven ice melt will overtake the Moon’s tidal friction as the primary brake on planetary rotation. For the first time in Earth’s history, the dominant force shaping the length of a day will not be celestial. It will be terrestrial.
Why Milliseconds Matter to Modern Life
A few thousandths of a second sounds like an abstraction. To a GPS satellite, it is a catastrophic error.
Global positioning systems function by timing how long it takes a radio signal to travel from a satellite to a receiver on the ground. Light travels roughly 300 meters in one microsecond. If the atomic clocks that govern GPS drift out of alignment with Earth’s actual orientation in space by even a tiny fraction of a second, the resulting position error can span city blocks.
Organizations like the International Earth Rotation and Reference Systems Service publish regular bulletins tracking the difference between precise atomic time and the planet’s irregular rotation. Since 1972, timekeepers at the National Institute of Standards and Technology have added 27 leap seconds to Coordinated Universal Time to keep the two systems synchronized. The last leap second was inserted on December 31, 2016.
The accelerated melting of polar ice introduces a new and unpredictable variable into those calculations. As Adhikari’s team noted, the planet’s spin is no longer a purely astronomical problem. It is now a climate problem.
The Axis Is Wandering in Response
The same redistribution of mass that slows the rotation also shifts the location of the spin axis itself. Scientists refer to this phenomenon as polar motion.
Using machine-learning algorithms to analyze 120 years of measurements, the research team found that 90 percent of recurring fluctuations in the axis position could be explained by changes in groundwater, ice sheets, glaciers, and sea level. The axis has wandered by approximately 30 feet over the past century.
A sudden eastward drift that began around 2000 was traced directly to accelerated melting in Greenland and Antarctica and to groundwater depletion in Eurasia. The evidence converges on a single point. Climate-driven changes in surface mass are now detectable at the scale of the entire planet.
The Long Goodbye to 24 Hours
A study from the University of Toronto published in Science Advances offers a useful reminder of how unusual this moment is. Led by theoretical astrophysicist Norman Murray, the research showed that for more than a billion years, the length of Earth’s day held steady at 19.5 hours. An atmospheric tide driven by the Sun resonated with the planet’s rotation, perfectly counteracting the Moon’s braking effect. That natural stalemate ended long before humans arrived.
The current acceleration is not natural. It is a direct consequence of ice loss driven by rising global temperatures. The length of day will reach 25 hours eventually, but it will arrive on a planet shaped by forces we are only beginning to measure.
For a simple comparison of how day lengths vary across the solar system, NASA’s Space Place offers a clear breakdown of planetary rotation periods.
Enjoyed this article? Subscribe to our free newsletter for engaging stories, exclusive content, and the latest news.
