As the world grapples with the widespread effects of climate change, an unexpected consequence has emerged: its impact on global timekeeping. Geophysicist Duncan Agnew of the Scripps Institution of Oceanography has highlighted a surprising finding that the melting ice sheets on Greenland and Antarctica are affecting Earth’s rotation.
The massive ice loss, primarily driven by global warming, is redistributing mass towards the equator, causing the planet to bulge outward at the waistline. This redistribution of mass is significant enough to slow down Earth’s rotation. The consequences of these changes are profound, as they directly impact the precision of time measured against Earth’s spin.
Internationally, time is governed by the coordinated universal time (UTC), which is synchronized with atomic clocks. These clocks are incredibly accurate, but they need regular adjustments to align with Earth’s rotation. Factors like gravitational interactions with celestial bodies and tectonic movements have traditionally influenced Earth’s rotational speed, but now, climate change is becoming a predominant factor.
The current system compensates for discrepancies in Earth’s rotation with the addition of “leap seconds,” a practice introduced in 1972 to adjust UTC. However, inconsistencies in when these adjustments occur—due to their dependence on geophysical and astronomical observations—pose challenges for industries relying on precise time, such as financial markets and satellite navigation.
Recognizing these challenges, a global consortium of metrologists in 2022 proposed phasing out leap seconds in favor of adding larger intervals of time less frequently, aiming to discuss this further in their 2026 meeting.
Interestingly, the slowdown in Earth’s rotation due to melting ice has extended the period between necessary time adjustments. Agnew notes that this change has pushed back the need for a leap second, which was last added in 2016. However, this is a temporary reprieve. The underlying acceleration of Earth’s outer layers, due to the slowing rotation of the core, will eventually necessitate a reversal in timekeeping adjustments—from adding to removing seconds from UTC.
The implications of these findings are significant as they underscore the pervasive impacts of climate change, extending even into the realm of timekeeping. The ongoing research by Agnew and his colleagues serves as a reminder of the interconnectedness of natural phenomena and human systems, and the need for adaptive strategies in response to our changing planet.
This evolving situation highlights not just the physical impacts of climate change but also the intricate adjustments humanity must make in systems as fundamental as timekeeping. As global discussions continue, the task of rethinking our approach to measuring time reflects the broader challenge of adapting to a rapidly changing world.
