Study Finds Human-Driven Sea-Level Rise Now Lengthening Earth’s Day

In 1695 Edmond Halley first suspected lunar tides were braking Earth’s spin; 20th-century astronomers quantified that drag at ≈2.3 ms per century. The new analysis suggests that within a single human lifetime, greenhouse-driven sea-level rise may rival and surpass that multi-billion-year lunar torque—something not glimpsed even during the rapid deglaciation 12,000 years ago. Much like the post-industrial carbon spike that now dwarfs natural CO₂ swings recorded in ice cores, this rotational perturbation reflects the broader Anthropocene pattern: human activity compressing geologic-scale forces into decades. The conclusion rests on proxy data and machine-learning reconstruction, so its precision depends on noisy foraminifera chemistry and model assumptions—caveats that future core samples or satellite gravimetry could refine. Yet if the estimate holds, millisecond drifts will accumulate, forcing new leap-second policies, GNSS recalibrations, and perhaps a redefinition of “24 hours” well before 2126—underscoring how climate change is beginning to rewrite even the celestial rhythms that have governed timekeeping for millennia.