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The climate crisis is leading to lengthier days, according to recent analyses, as the significant melting of polar ice reshapes our planet. This phenomenon serves as a compelling illustration of how human activities are altering Earth’s natural processes, rivaling changes that have occurred over billions of years.
While the increase in the length of each day is measured in milliseconds, this seemingly minor shift has the potential to disrupt critical systems such as internet traffic, financial transactions, and GPS navigation, all of which depend on accurate timekeeping.
Historically, the Earth’s day has been gradually lengthening due to the gravitational influence of the moon on the planet’s oceans and land. However, the ongoing melting of the Greenland and Antarctic ice sheets—driven by human-induced global warming—is redistributing water from high latitudes into the world’s oceans. This process results in an increase in water volume near the equator, causing the Earth to become more oblate (or bulging), which in turn slows its rotation and further extends the length of the day.
Recent research has also highlighted the broader planetary impacts of human activity, revealing that the redistribution of water has caused a shift in the Earth’s axis of rotation—altering the positions of the north and south poles. Other studies have indicated that human carbon emissions are contributing to a reduction in the stratosphere’s thickness.
“We can observe humanity’s influence on the entire Earth system, not just in localized phenomena such as temperature increases, but in fundamentally altering how the planet rotates and moves through space,” stated Professor Benedikt Soja from ETH Zurich in Switzerland. “Our carbon emissions have accomplished this transformation in just 100 to 200 years, whereas the natural processes that previously governed these changes have spanned billions of years. This is truly remarkable.”
Human timekeeping relies on atomic clocks, which are exceptionally precise. Nevertheless, the duration of a day, defined as one complete rotation of the Earth, can vary due to factors such as lunar tides, climate changes, and the gradual rebound of the Earth’s crust following the retreat of ice sheets from the last ice age.
These variations must be accounted for, as Soja emphasizes: “All the data centers that facilitate the internet, communications, and financial transactions are predicated on precise timing. Accurate timekeeping is also essential for navigation, particularly for satellites and spacecraft.”
The study, published in the Proceedings of the National Academy of Sciences of the USA, employed observations and computer simulations to evaluate the effect of melting ice on the length of the day. Between 1900 and 2000, the rate of lengthening varied from 0.3 to 1.0 milliseconds per century (ms/cy). However, since 2000, with the acceleration of ice melting, this rate has increased to 1.3 ms/cy.
“This current rate is likely the highest it has been in several thousand years,” the researchers noted. “It is expected to stabilize at approximately 1.0 ms/cy for the next few decades, even if greenhouse gas emissions are significantly reduced. Should emissions remain unchecked, the slowing rate could rise to 2.6 ms/cy by 2100, surpassing lunar tides as the primary contributor to long-term variations in day length.”
Dr. Santiago Belda from the University of Alicante in Spain, who was not involved in the research, remarked: “This study represents a significant advancement because it confirms that the alarming loss of ice in Greenland and Antarctica directly impacts day length, causing our days to grow longer. This variation has critical implications not only for our methods of measuring time but also for GPS and other technologies integral to our modern lives.”
