New research suggests human-caused climate change is altering the Earth’s rotation and changing the length of our days. This finding, published in the Proceedings of the National Academy of Sciences, underscores the consequences of global warming.
International scientists, led by researchers from ETH Zürich and NASA’s Jet Propulsion Laboratory, have found that melting polar ice due to climate change is altering Earth’s rotation speed, gradually lengthening each day. This trend is expected to accelerate if emissions persist.
Dr. Surendra Adhikari, a geophysicist at NASA’s Jet Propulsion Laboratory and one of the study’s authors, emphasized the importance of these findings. “This is a testament to the impact of ongoing climate change,” he said. “In barely 200 years, we will have altered the Earth’s climate system so much that we are witnessing its impact on Earth’s spin.”
Earth’s rotation changes could have significant implications for our technology-dependent world. GPS systems and other technologies rely on precise timekeeping, which could be affected by these changes.
Another cause of the Earth’s rotational slowdown is tidal friction triggered by the moon, according to a statement from ETH Zurich. The new research concludes, “If humans continue to emit more greenhouse gases and the Earth warms up, this would ultimately have a greater influence on the Earth’s rotational speed than the moon, which has determined the increase in the length of the day for billions of years.”
The Earth’s rotation speed is influenced by factors like the planet’s fluid core processes and the moon’s gravitational pull. Historically, the moon’s dominance increased the day’s length by milliseconds per century. New research suggests climate change is becoming a significant factor.
Dr. Benedikt Soja, a study author and assistant professor of space geodesy at ETH Zurich, explained the potential shift in dominance: “If the world continues emitting planet-heating pollution, climate change could become the new dominant factor, surpassing the moon’s role.”
The phenomenon is related to the Earth’s mass redistribution. As the planet warms, glaciers and ice sheets melt, causing water to flow from the poles toward the equator. This changes the planet’s shape, flattening it at the poles and causing it to bulge more in the middle, slowing its rotation.
Dr. Soja used a figure skating analogy, “It’s like a skater doing a pirouette, first holding her arms close and then stretching them out.” As the skater extends their arms, their spin slows – a principle that applies to Earth’s rotation.
The research team examined 200 years from 1900 to 2100, using observational data and climate models, and found that the impact of climate change on day length has increased significantly.
In the 20th century, climate change-induced sea level rise caused day length to vary by 0.3 to 1 milliseconds. Over the past two decades, scientists calculated an increase of 1.33 milliseconds per century, “significantly higher than in the 20th century,” according to the report.
If greenhouse gas emissions keep rising, the rate of change could increase more. The study projects that by the end of this century, climate change could increase the length of a day by 2.62 milliseconds – surpassing the moon’s natural impacts.
These changes may seem imperceptible to humans, they have important implications for technology and potentially for geological processes. Some studies have suggested a correlation between increased day length and earthquake frequency, but this connection requires further research.
The study reveals a intriguing phenomenon: the shift in Earth’s axis of rotation, known as polar motion. Mostafa Kiani Shahvandi, a doctoral student at ETH Zurich and lead author of the study, explained, “We present a complete explanation for the causes of long-period polar motion. In other words, we now know why and how the Earth’s axis of rotation moves relative to the Earth’s crust.”
Researchers predict a 10-meter movement per hundred years in the Earth’s axis of rotation, significant in geological terms, demonstrating the impact of human activity on our planet.
These findings have implications beyond Earth. Understanding rotational changes is crucial for space navigation, where slight deviations can lead to significant errors over vast distances. Dr. Soja highlighted, “Even if the Earth’s rotation changes slowly, it must be considered when navigating in space, like when sending a space probe to another planet.”
As our understanding of Earth systems grows, so does our awareness of their interconnectedness. The climate crisis could affect natural processes within the planet’s core by shifting its axis of rotation.
Dr. Soja concluded with a sobering reflection: “We have to consider that we are now dominating effects that have been in action for billions of years and influencing Earth’s orientation in space.”
