It may seem to some that the days drag on and get longer. Although this is a subjective perception of time influenced by what a person is doing, according to Austrian and Swiss scientists, the days on Earth are really getting longer. Although this does not surprise scientists, they expect it due to the development of the Solar System, but the pace of this change is striking. According to experts, it is extremely fast and climate change is to blame.
Scientists from the University of Vienna and the University of Zurich found that the length of the day lengthens by 1.33 milliseconds per century. According to their analysis, this is a faster change than at any time during the last 3.6 million years of the planet’s history. According to the authors of the study, the main cause is climate change. The melting of the polar ice caps and mountain glaciers raises the sea level and at the same time slows down the rotation of the Earth.
The mechanism is compared to a figure skater. When he spreads his arms, he slows down the spin in a pirouette. Likewise, water from melting ice flows from the poles toward the equator, moving the planet’s mass further away from its axis of rotation. „While natural cycles have driven change in the past, the current rate of human-induced change is so high that it stands out in climate history.” said study co-author Professor Benedikt Soja from the University of Vienna.
“Only once – about two million years ago – has the rate of day length change been nearly comparable, but never before or since has the planetary figure skater raised her arms and sea levels as rapidly as between 2000 and 2020,” added Soja. Days on Earth were not exactly twenty-four hours long. The speed of rotation can be affected by, for example, the gravity of the Moon, processes deep below the Earth’s surface, or changes in the atmosphere. However, these small fluctuations are usually a natural part of planetary cycles.
However, according to previous studies by Professor Soja and his colleagues, human activity is beginning to affect the Earth’s rotation as strongly – or even more strongly – than natural factors. Mass shifts caused by melting glaciers and rising ocean levels increase the planet’s so-called moment of inertia. This leads to the slowing down of its rotation and the lengthening of the day. The changes are very small so far and people will not notice them. However, they can be a problem for systems that require extremely accurate timekeeping.
“Even if it’s only milliseconds, these changes can disrupt systems that need extremely precise time data. These include space navigation, GPS systems, and satellite navigation or atomic clock synchronization.” Professor Soja explained. If climate change continues, scientists expect further slowing of the Earth’s rotation. According to estimates, the days could lengthen by as little as 2.62 milliseconds per century since the 1980s.
