Recent research has illuminated the profound ways in which climate change is impacting Earth's fundamental physical properties, reaching deep into its core. The ongoing melting of polar and glacial ice, driven by global warming, is causing water that was once concentrated at the polar regions to be redistributed toward the equator. This redistribution of mass affects the Earth's rotation, leading to a gradual increase in the length of our days.

A recent study published in the journals Nature Geoscience and Proceedings of the National Academy of Sciences provides compelling evidence of this phenomenon. The research suggests that the profound melting of ice has been significant enough to influence the Earth’s axis—the imaginary line around which the planet rotates. These shifts are not confined to surface-level changes; they are inducing alterations beneath the Earth's surface, impacting the dynamics of fluids within the planet’s molten core.

The findings of this study, along with similar research published in March, highlight the extensive impact of human activities on the Earth's fundamental physical properties. According to Benedikt Soja, an assistant professor of space geodesy at ETH Zurich and one of the study’s authors, "You can add Earth’s rotation to this list of things humans have completely affected." The change in Earth's rotational speed could potentially rival the influence of tidal forces exerted by the moon, provided that carbon emissions continue at their current elevated levels.

The speed at which Earth rotates is influenced by its shape and the distribution of its mass, governed by various counteracting forces. A useful analogy is the figure skater who spins on ice: when the skater’s arms are extended, the rotation is slower; when the arms are drawn in, the spin accelerates. Similarly, the friction from ocean tides, driven by the moon’s gravitational pull, has historically been the primary factor slowing Earth's rotation. Conversely, the gradual rebound of Earth’s crust in high-latitude regions, following the removal of Ice Age glaciers, has contributed to a speeding up of the planet's rotation.

Traditionally, these factors have been predictable influences on Earth's angular velocity. However, the rapid melting of ice caused by global warming introduces a new and potent force. If current carbon emissions persist, the impact of ice loss could eventually surpass the moon's influence on Earth’s rotation. "In the worst scenarios, then yeah, climate change would become the most dominant factor," Soja noted.

Another crucial element affecting Earth’s spin is the motion of fluids within its core. Scientists have long understood that these fluids can either accelerate or decelerate the planet's rotation, with variations occurring over 10- to 20-year intervals. Presently, the core is inducing a slight acceleration of Earth's spin, partially counteracting the deceleration caused by climate change. Nonetheless, as climate change continues to progress, it appears to be influencing the core’s dynamics as well.

The researchers constructed a 120-year model of polar motion to examine shifts in the Earth’s axis over time. Their findings indicate that the redistribution of mass due to melting ice has contributed to minor fluctuations in polar motion. Soja estimated that climate change is likely responsible for approximately 1 meter of axis shift over a decade.

These changes form part of a feedback loop where alterations in Earth's surface impact its interior. "The rotation changes slightly, and that, we believe, can indirectly have an effect on the core," Soja explained. Measuring this interaction directly is challenging due to the inaccessibility of the core.

The implications of these findings are extensive, affecting both timekeeping and space navigation. Accurate timekeeping is critical for maintaining Coordinated Universal Time (UTC). Research published in March suggested that climate change has delayed the need for a “negative leap second” to align global clocks with Earth’s rotation. Duncan Agnew, a geophysicist at the Scripps Institution of Oceanography, noted that the new research complements his earlier work, extending the findings into future climate scenarios.

Thomas Herring, a professor of geophysics at the Massachusetts Institute of Technology, who was not involved in the recent studies, found the research plausible. He explained that "large-scale" surface processes can indeed penetrate to the fluid core, influencing its behavior.

Overall, this research underscores the profound and far-reaching impacts of climate change, demonstrating that human activities are not only reshaping the Earth's surface but also affecting its internal dynamics and fundamental physical properties.