Scientists from countries such as Switzerland and the United States have used artificial intelligence (AI) technology to monitor the impact of climate change on the Earth's rotation. According to the research results, they believe that human caused climate change is constantly disrupting the Earth's rotation, leading to an increase in daily duration (day length). As climate change intensifies, this trend will continue to accelerate. The relevant paper was published in the recently published issue of the Proceedings of the National Academy of Sciences in the United States. Researchers warn that changes such as longer days may not be easily noticeable at first, but they could have serious chain reactions, including forcing people to introduce negative leap seconds, affecting space navigation, and even altering the state of the Earth's core. The duration of a day on Earth has been constantly changing. Currently, a day on Earth lasts approximately 24 hours (86400 seconds), but this duration is not fixed. About 1 billion years ago, it may only take 19 hours for the Earth to complete one rotation. On shorter time scales, the duration of the day also fluctuates frequently. For example, in 2020, the Earth's rotation speed was faster than at any time since records began in 1960. In 2021, the Earth's rotation speed slowed down again, but on June 29, 2022, humanity experienced the shortest day in history. On that day, the Earth's rotation speed set a record for the fastest, 1.59 milliseconds less than the standard time. However, in the long run, the speed of Earth's rotation has been slowing down for thousands of years, with daily growth increasing. A report in the Journal of the Royal Society of Mathematics and Physics in the UK pointed out that over the past 27 centuries, the average daily length has increased by about 1.8 milliseconds per century. The main reasons for this phenomenon include tectonic plate movement, changes in core rotation, and the influence of lunar gravity. Among them, the moon currently has the greatest impact. Specifically, the moon exerts a pulling force on the Earth, causing tidal effects that gradually slow down the Earth's rotation speed, resulting in longer days. In addition, scientists have gradually realized that human caused climate change is also interfering with the Earth's rotation, leading to longer days. In the past few decades, human activities have caused global warming, accelerating the melting of glaciers and ice sheets in the polar regions of the Earth, especially Greenland and Antarctica. Melted water flows from the Earth's poles towards the equator and gathers here. This changed the shape of the Earth, with the poles flattening and the middle slightly bulging. Due to more weight being distributed further away from the center of the Earth, the rotation speed of the Earth slows down. The principle is similar to that of an ice skater rotating around their own axis on the ice, extending their arms from the top of their head to the sides of their body will slow down the rotation speed. In the latest study, scientists from ETH Zurich, Caltech, and the University of Alberta used advanced AI programs to predict how the Earth's rotation will change over time, combining real-world data with physical laws. Benedikt Suja, a geodesist at the Swiss Federal Institute of Technology in Zurich, said that their simulation results show that the melting of polar glaciers caused by global warming is changing the speed of Earth's rotation, leading to longer days. With the intensification of climate change, this trend will further accelerate. Suja said that climate change is currently increasing the length of days on Earth by about 1.3 milliseconds per century. But based on existing global temperature models, by the end of the 21st century, climate change will increase the length of days on Earth by 2.6 milliseconds per century, becoming the biggest factor affecting Earth's rotation. Suja pointed out that one of the most likely impacts of a longer day on precise timing and space navigation is the need to introduce negative leap seconds. This means that on certain days in the future, we will need to subtract one second from global standard time to accommodate longer days. In 1971, the International Conference on Weights and Measures passed a resolution to use Coordinated Universal Time to measure time. When the difference between Coordinated Universal Time and Universal Time exceeds 0.9 seconds, the International Earth Rotation Service (IERS) is responsible for moving Coordinated Universal Time forward or backward by 1 second, which is called a leap second. There is a difference between positive and negative for 'leap second', which means adding 1 second. At that time, atomic clocks around the world will display the peculiar time of 'X: X: 60'. And 'negative leap second' means subtracting 1 second, which means the day ends at 23:59:58. On March 28th of this year, Duncan Carl Agnew, a scientist at the University of California, San Diego, published a paper in the journal Nature stating that negative leap seconds may appear as early as 2029. Some scientists are concerned that introducing negative leap seconds may disrupt the timing of computers and smartphones, as many computer programs default to positive leap seconds and require reprogramming of computer systems, a process that is prone to errors. Sujia also pointed out that the increase in daily length may have an impact on space positioning and navigation. Even a small time error can have a significant impact when sending a space probe to another planet. The Sujia team warns that changes in the Earth's rotational axis may also alter the rotation speed of the Earth's core, thereby affecting the rate of increase in daily length. However, scientists still need to conduct in-depth research to explore this potential interaction. (New Society)