The leap second is being affected by climate change, scientists warn – The Washington Post

Melting polar ice is affecting Earth's rotation and might lead to a "negative leap second."
March 27, 2024
man and woman standing cracked sea ice under gray sky
Photo by Roxanne Desgagnés, Unsplash


  • Climate change is caused by the melting of the polar ice caps, causing Earth’s rotation to be affected.
  • Scientists may have to consider inserting a “negative leap second” into the calendar to ensure Earth’s rotation stays in sync with Coordinated Universal Time.
  • The gravitational dance Earth is in with various celestial bodies and its core make timekeeping a challenging science.


  • The planet’s fluctuating spin rate is carefully tracked by the International Earth Rotation and Reference Systems Service (formerly the only slightly less bombastically named International Earth Rotation Service). In the early 1970s, Earth was clearly slowing down in its rotation, and a gap was forming between atomic time and astronomical time. Thus was born the “leap second” to adjust for the fact that the “day” was getting a bit longer.
  • …although the core is causing the planet to spin faster, the planetary shape changes caused by a warming climate are slowing that process. Absent this effect, Agnew wrote, the overall acceleration of the planet’s rotation might require timekeepers to insert a “negative leap second” at the end of 2026. Because of climate change, that might not be necessary until 2029, he found.

Read the full post at Google News - Climate.

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