With climate change, the days will become longer literally, not just figuratively. This is the main conclusion of a study published this Monday in the PNAS magazine by the team of Mostafa Shahvandifrom the Swiss Federal Institute of Technology in Zurich (ETHZ), which concludes that the length of the day on Earth is increasing at an unprecedented rate, which will double by the end of this century if we do not reduce greenhouse gas emissions.
The cause is a redistribution of mass caused by rising sea levels and warming temperatures, which has caused the planet to spin more slowly and day length to increase from 0.3 to 1 millisecond per century before 2000 to about 1.33 milliseconds over the past 20 years. If greenhouse gas emissions continue to rise, the researchers warn, climate change could lead to an increase of 2.62 milliseconds per century by 2100, outweighing the effect of tidal friction from the Moon on planetary rotation.
More impact than we think
While it is true that 2.62 milliseconds per century is not something we will notice in our daily lives, it will affect different technological systems such as GPS systems, the measurement of coordinated universal time and space travel. “Although the Earth’s rotation changes very slowly, this effect must be taken into account in space navigation, for example, when sending a space probe to another planet,” he explains. Benedikt SojaProfessor of Space Geodesy at ETHZ and senior author of the study. “A small deviation of just one centimetre on Earth can add up to hundreds of metres over the enormous distances involved. Otherwise, it would not be possible to land in a specific crater on Mars,” he says.
According to the authors, these findings reveal the planetary impact of modern climate change on Earth. “Humans have a greater impact on our planet than we realize and this naturally imposes a great responsibility on us for the future of our planet,” says Soja. Specifically, climate change is causing the ice masses of Greenland and Antarctica to melt and water from the polar regions to flow into the world’s oceans, especially towards the equatorial region.
“It’s like when a figure skater does a pirouette, first with his arms close to his body and then stretching them out,” explains the researcher. “The rotation, which was initially fast, becomes slower because the masses move away from the axis of rotation, increasing physical inertia. In physics, we talk about the law of conservation of angular momentum, and this same law also governs the rotation of the Earth. If the Earth rotates more slowly, the days become longer. Therefore, climate change is also altering the length of the day on Earth, even if only minimally.”
Altering the axis of rotation
As bad news never comes alone, the same researchers published a few days ago another study in the journal Nature Geoscience in which they show, from the models, that the changes in mass on the surface are also modifying the axis of rotation. This means that the points where the axis of rotation meets the Earth’s surface move. The reason is that deep in the Earth’s mantle, where rock becomes viscous due to high pressure, displacements occur over long periods of time. And there are also heat flows in the liquid metal of the Earth’s outer core, responsible both for generating the Earth’s magnetic field and for causing changes in mass.
Climate change may even be affecting processes deep inside the Earth and have a greater scope than previously assumed.
Mostafa Shahvandi
— Researcher at the Swiss Federal Institute of Technology Zurich (ETHZ)
“For the first time, we have presented a complete explanation of the causes of long-period polar motion,” says Shahvandi. “In other words, we now know why and how the Earth’s rotation axis moves relative to the Earth’s crust.” This means, according to the researchers, that climate change is causing the Earth’s rotation axis to move, and it appears that the feedback from the conservation of angular momentum is also changing the dynamics of the Earth’s core. “Therefore, ongoing climate change might even be affecting processes in the Earth’s interior and be more far-reaching than previously assumed,” Shahvandi concludes.
A shake to the clocks
The new work joins other recent studies, such as the analysis published in March 2024 by the University of California San Diego (USCD) geophysicist Duncan Agnewin which he warned that these changes in the speed of rotation of the planet will force us to make adjustments in our way of measuring time and the scientists who are in charge of maintaining the Coordinated Universal Time (UTC) will have to introduce periodic adjustments so that the time measured by atomic clocks does not become out of sync.
For Santiago Beldaa distinguished researcher in the Geodesy and Spatial Dynamics Group at the University of Alicante, this study is a major breakthrough because it confirms that the worrying loss of ice that both Greenland and Antarctica are experiencing has a direct impact on the length of the day, causing our days to become longer. “This fact has been demonstrated and quantified rigorously, using a multitude of geodetic observations and models that attempt to reliably describe where the water from the melting of the polar zones is moving,” he explains in statements to SMC Spain.
“This increase in day length, caused by a decrease in the speed of the Earth’s rotation, has been accentuated in recent years (from 2000 onwards) by the effects of climate change and greenhouse gases, where ice melting is even greater due to the alarming increase in temperature that our planet is experiencing,” he concludes. “This variation in day length has critical repercussions not only on our way of measuring time, but also on GPS and other technologies that govern our modern life.”
Source: www.eldiario.es
