A new landmark study published in the Proceedings of the National Academy of Sciences has found the reasons for this phenomenon
Of the several million arguments on rising temperatures, melting ice caps, and violent weather events over climate change, here is a new and surprising consequence of global warming that is just making headlines: the lengthening of the day. Recent research into climate change portrays it as making the Earth rotate slower, consequently increasing the length of our days. The discovery represents a small window into the complex interlinkages of our planet's systems and just how great an effect our actions have on the natural world.
A new landmark study published in the Proceedings of the National Academy of Sciences has found the reasons for this phenomenon. This research explains how the melting of the polar ice caps of Greenland and Antarctica is redistributing water and increasing mass towards the equator. This change in mass redistribution affects the rotation of our Earth, just like a figure skater does by shifting her arms to change the rate of how fast she spins.
Surendra Adhikari, a co-author of the study from NASA's Jet Propulsion Laboratory, explains, It's like when a figure skater does a pirouette, holding her arms close to her body and then stretching them out."
"The initially fast rotation becomes slower because the masses move away from the axis of rotation, increasing physical inertia," she added.
Traditionally, a day's length is benchmarked on the so-termed standard of 86,400 seconds, but recent observations show this baseline has stretched by a few milliseconds. The authors used various sophisticated techniques to monitor the subtle yet significant changes. They used some of the most demanding technologies available, including Very Long Baseline Interferometry (VLBI), which is how long radio signals take to reach separate locations on Earth. It also used the Global Positioning System for accurate measurements of Earth's rotation, with an accuracy of about one hundredth of a millisecond. It used ancient eclipse records from thousands of years ago.
The findings are not just a result of scientific curiosity, however. They have important implications for our understanding of Earth's future. Adhikari and his colleagues calculate that by the end of the 21st century, climate change could make days 2.2 milliseconds longer under a high-emission scenario. Such an increase exceeds the current main disturbing factor of lengthening the day: the tidal acceleration of the Moon resulting from the action of tidal forces, which over millions of years has been slowing down the Earth's axial rotation by about 2.40 milliseconds per century.
While a few millisecond shifts may sound innocuous, they have far-reaching implications. For space missions, Earth's orientation is simply critical. The tiniest deviation in Earth's orientation might translate into highly incorrect navigation by spacecraft that are bound to probe the depths of our solar system and beyond.
The authors also identify a selected portion of how climate change is causing changes on Earth beyond these immediate concerns of temperature and sea level rise. Changes in mass, such as moving from the poles to the equator, alter Earth's physical properties and thereby introduce variables into the complex systems that govern Earth's rotation.
The finding that artificial climate change is stretching our days may seem minor, but it's part of a much bigger story: we are setting chain reactions in motion throughout Earth's systems. As if the effects of global warming weren't enough to contend with, this study serves as a reminder that every single aspect of the climate crisis is intertwined.
