This story was originally published by the Guardian and is reproduced here in collaboration with the Climate Desk.
The analysis shows that the climate crisis is causing the length of each day to lengthen as the mass melting of polar ice reshapes the planet.
The phenomenon is a remarkable example of how human actions are transforming the Earth, scientists said, and competing with natural processes that have existed for billions of years.
The change in day length is on the order of milliseconds, but that’s enough to potentially disrupt internet traffic, financial transactions and GPS navigation, all of which rely on accurate timekeeping.
The length of an Earth day has been steadily lengthening over geologic time due to the Moon’s gravitational drag on the planet’s oceans and land. However, melting glaciers in Greenland and Antarctica due to human-caused global warming has redistributed water stored at high latitudes to the world’s oceans, leading to more water in seas closer to the equator. This makes the Earth flattened – or fatter – slowing the planet’s rotation and lengthening the day even more.
Humanity’s planetary impact has also recently been demonstrated by research showing that the redistribution of water has caused the movement of the Earth’s axis of rotation – the north and south poles. Other work has revealed that human carbon emissions are shrinking the stratosphere.
“As humans, we can see our impact on the entire Earth system, not just locally, like the rise in temperature, but really fundamentally by changing how it moves in space and rotates,” said Professor Benedikt Soja of ETH Zurich in Switzerland, one of the them. the world’s leading universities in the field of science and technology. “Given our carbon emissions, we could do it in just 100 or 200 years. Whereas the governing processes used to take place over billions of years, and that’s striking.”
Human timekeeping is based on atomic clocks that are extremely accurate. However, the exact time of day – one rotation of the Earth – varies due to lunar tides, climatic effects and some other factors, such as the slow rebound of the Earth’s crust after the retreat of the ice sheets formed in the last ice age. .
These differences need to be taken into account, Soja said: “All data centers that run the Internet, communications and financial transactions are based on precise timing. We also need accurate time knowledge for navigation, especially for satellites and spacecraft.
“Given our carbon emissions, we could do it in just 100 or 200 years. Whereas the governing processes used to take place over billions of years, and that’s striking.”
Research published in Proceedings of the National Academy of Sciences of the USA, used observations and computer reconstructions to assess the effect of ice melt on day length. The rate of deceleration varied between 0.3 and 1.0 milliseconds per century between 1900 and 2000. But since 2000, as melting accelerated, the rate of change also accelerated to 1.3 milliseconds per century.
“This current rate is probably higher than at any time in the past several thousand years,” the researchers said. “It is projected to remain at around 1.0 milliseconds per century for the next few decades, even if greenhouse gas emissions are significantly reduced.” If emissions are not reduced, the rate of slowdown will increase to 2.6 milliseconds per century by 2100, overtaking monthly tides as the single largest contributor to long-term changes in day length, they said.
Dr. Santiago Belda of the University of Alicante in Spain, who was not part of the research team, said: “This study is a major advance because it confirms that the alarming ice loss that Greenland and Antarctica are experiencing has a direct impact on the length of the day, causing our days are lengthening. This change in the length of the day has profound implications not only for how we measure time, but also for GPS and other technologies that govern our modern lives.”