In 2022, international timekeepers voted to phase out the leap second\u2014an extra tick of time added to account for Earth\u2019s erratic rotation. But as our planet\u2019s spin grows weirdly faster, timekeepers are seriously considering introducing a larger fix: the leap hour.<\/p>\n
Every four years, scientists and timekeeping authorities convene at the General Conference on Weights and Measures<\/a> (CGPM) to discuss relevant news about standards for maintaining the Coordinated Universal Time (UTC). After abandoning leap seconds in 2022, the conference resolved to decide on an alternative with a higher time limit by 2035. However, due to recent upticks in Earth\u2019s rotation rate, timekeepers are having to reckon with negative leap seconds\u2014the consequences of which are prompting authorities to find a solution before the 2035 deadline.<\/p>\n And one viable solution is to replace the leap second with the leap hour. Timekeepers will vote on this idea during the next CGPM<\/a>, which will be held in October this year.<\/p>\n \u201cWe estimated that if we wait till 2035, we have 30 percent risk of a negative leap second,\u201d Patrizia Tavella, director of the time department at the International Bureau of Weights and Measures (BIPM), told Scientific American<\/a>.<\/p>\n Why the hurry? <\/p>\n A full day on Earth\u2014the time it takes for our planet to complete one rotation on its axis\u2014lasts approximately 86,400 seconds. But factors such as the Sun\u2019s position or the Moon\u2019s orbits can create small variations, which humanity is much more privy to thanks to advances in scientific technology. In 1972, the BIPM introduced a leap second to account for the tiny discrepancies between UTC and UT1, or astronomical time.<\/p>\n To most of us, a difference of a couple milliseconds probably seems insignificant. But to people working with high-precision systems in communications, GPS, banking, etc., even the tiniest error margins can mess up entire networks. For instance, a leap-second-related bug caused<\/a> failures in Cloudflare\u2019s DNS service when a leap second was added to UTC at midnight on January 1, 2017.<\/p>\n In other words, ironically, leap seconds were created to fix time discrepancies but ended up creating a \u201ctechnical nightmare\u201d at odds with modern society\u2019s highly computerized infrastructure, according to a report<\/a> on the 2022 resolution by The New York Times.<\/p>\n Entering the negative <\/p>\n In that sense, some experts believed that the leap second has \u201calways been a problem,\u201d as Judah Levine, a former physicist for the time division at the U.S. National Institute of Standards and Technology, told Scientific American. But the problem became more potent as, starting in 2016, Earth started to spin unusually fast<\/a>.<\/p>\n For instance, on July 4 of 2024, Earth set a new record by completing its daily spin 1.66 milliseconds faster than usual. Around one year later on July 10, 2025, it spun 1.36 milliseconds faster than usual, with other shorter-than-usual days occurring on July 9 and July 22. This has led experts to warn<\/a> about a \u201cnegative\u201d leap second\u2014subtracting a second from UTC\u2014to keep UTC aligned with UT1 as early as 2029.<\/p>\n