Scientists say the phenomenon is clear evidence that human actions are changing the Earth, on par with natural processes that have existed for billions of years.
The change in the length of a day is only measured in milliseconds, but is enough to disrupt internet traffic, financial transactions and GPS navigation, all of which depend on accurate time tracking.
The change in the length of a day is only measured in milliseconds, but it is enough to disrupt modern life. Photo: Bloomberg
The length of Earth's days has steadily increased over geologic time due to the Moon's gravitational pull on the planet's oceans and land. However, the melting of ice sheets in Greenland and Antarctica due to human-caused global warming has redistributed water stored at high latitudes into the world's oceans, resulting in more water in the seas near the equator. This makes the Earth flatter - or fatter - which slows the planet's rotation and lengthens the days even further.
Humanity's impact on the planet has also been recently demonstrated by research showing that water redistribution has shifted the Earth's axis of rotation - the north and south poles. Other studies have also shown that humanity's carbon emissions are shrinking the stratosphere.
“We can see the impact of humans on the entire Earth system, not just locally, like rising temperatures, but really fundamentally, changing the way the Earth moves in space and rotates,” said professor Benedikt Soja of the Swiss Federal Institute of Technology.
“Because of the huge amount of carbon emissions, we have done this in just 100 or 200 years. Whereas previous management processes took billions of years, and that is incredible,” he added.
The study, published in the Proceedings of the National Academy of Sciences, used observations and computer reconstructions to assess the impact of ice melt on the length of the day. The rate of slowing varied from 0.3 to 1.0 milliseconds per century (ms/cy) between 1900 and 2000. But since 2000, as the melt rate increased, the rate of change has also increased to 1.3ms/cy.
“This current rate is likely to be higher than at any time in the past several thousand years,” the researchers said. “This rate is expected to remain at approximately 1.0 ms/cy for the next several decades, even if greenhouse gas emissions are severely limited.”
If emissions are not cut, the rate of slowing will increase to 2.6 ms/cy by 2100, surpassing the Moon as the largest single contributor to long-term variations in the length of days on Earth.
“This change in the length of day has important implications not only for the way we measure time, but also for GPS and other technologies that govern modern human life,” said Dr Santiago Belda of the University of Alicante in Spain.
Nguyen Khanh (according to Guardian)
Source: https://www.congluan.vn/khung-hoang-khi-hau-dang-khien-ngay-dai-hon-post303850.html
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