Study: Melting polar ice slows Earth’s rotation, alters timekeeping

A recent study suggests that human-induced climate change, specifically the melting of polar ice, has marginally decelerated the Earth’s rotation, potentially impacting time measurement methods. Despite this slowdown, the Earth still rotates slightly faster than in the past, marking a historic occurrence where global timekeepers might need to subtract a second from clocks.

The study, published in the Nature journal, proposes the necessity of a “negative leap second” around 2029 to synchronize universal time with the altered rotation. Without the influence of melting ice, this adjustment would have been required as early as 2026.

According to Duncan Agnew, the study’s author from the Scripps Institution of Oceanography at the University of California, Greenland and Antarctica’s ice melting redistributes the Earth’s mass, affecting its rotation. This redistribution slows the planet’s rotation as the concentration of mass shifts away from the poles towards the equator.

Agnew illustrates this phenomenon using the analogy of a figure skater: when a skater extends her arms or legs, she slows down, but when she draws them inward, she spins faster. Similarly, the melting ice alters the Earth’s rotational speed.

The accelerating trend of polar ice melting, primarily driven by human activities, suggests that human-induced climate change is contributing to the Earth’s altered rotation. Agnew notes the unprecedented nature of these changes, highlighting the measurable impact humans have on the Earth’s rotational dynamics.

The study underscores the significance of melting polar ice as a novel factor affecting the Earth’s spin, alongside other influences such as ocean tides and fluid movement within the Earth’s core.