Climate change's impact on the speed of Earth's rotation may lead to a global time plight

One of the major concerns that has been shaking the world for the past few decades is global warming. Though countries are driving towards sustainable and climate-friendly operations in every walk of life, we're still a long way from reversing the impacts of global warming. As a result, we are now expecting a substantial influence on global timekeeping. A recent study titled: "A global timekeeping problem postponed by global warming," published in Nature Journal, mentions this issue. Turns out, if the Earth keeps heating up, a negative leap second might be added to the time settings in a few years.

Coordination in timekeeping exists worldwide, which is significant for the accurate functioning of computer networks. One crucial aspect of this global timekeeping is including an extra second, which is referred to as a "leap second" every few minutes. So, once in a while, a minute lasts for 61 seconds. As per the Naval Meteorology and Oceanography Command in the U.S., the leap seconds can be either positive or negative and so far, all leap seconds have been positive ever since leap second was taken into account for the first time in 1972 when computer networks were evolving. As of January 2020, there have been 28 leap seconds in the 48 years. But now, as per the study conducted by Duncan Carr Agnew, a geophysicist at Scripps Institution of Oceanography at UC San Diego, global timekeeping would require including a negative leap second around 2028 due to rising sea levels.

In 2023, it was observed that the difference between the days defined by Earth's rotation and by an atomic clock was only 80 microseconds. A leap second is the result of accumulation of this time difference over a few years. So, last year, the time difference added up to just 0.03 seconds, which was less in comparison to previous observations. As per the study, this signified that the Earth's rotation was slower than it was before. So, why did the Earth slow down? There were two causes. The first one was global warming, which caused the melting of polar ice caps, leading to a rise in ocean levels. So, the mass has now shifted from the poles to the equator region, leading to a slower rotation of the planet since 1990.

"Even a few years ago, the expectation was that leap seconds would always be positive and happen more and more often," stated Agnew and added, "But if you look at changes in the Earth's rotation, which is the reason for leap seconds, and break down what causes these changes, it looks like a negative one is quite likely. One second doesn't sound like much, but in today's interconnected world, getting the time wrong could lead to huge problems." However, even if we eliminate the impacts of global warming, the negative leap second might be included because of the second reason - the change in motion of the Earth's core. The movement of a huge mass of molten iron layers in the planet's core interacts to create the Earth's magnetic field. The core's motion also decides if the Earth would spin on its axis faster or slower. Recent observations have identified that the core has slowed down substantially, leading to the rest of the solid part of Earth spinning faster. 

As solid Earth rotates faster, one day has become 0.0025 seconds shorter now compared to 50 years ago. If the core's slower motion continues, days will get shorter inevitably in the future, irrespective of how global warming impacts the planet. The atomic-time day displayed in our smartphones and computers will need a negative leap second to be added every so often. Considering all potential influencing factors, by 2028, the negative leap second might be added. If not for global warming, this negative leap second would have been included three years earlier. Among the massive threats that global warming poses, delaying this global timekeeping crisis is a small but notable advantage.