Recent analysis reveals that the climate crisis is causing the Earth’s days to lengthen, with the mass melting of polar ice reshaping the planet. This phenomenon showcases humanity’s significant impact on Earth, rivaling natural processes that have persisted for billions of years.
The extension of each day, although measured in milliseconds, has profound implications. It can potentially disrupt internet traffic, financial transactions, and GPS navigation, all of which rely on precise timekeeping.
Historically, the length of Earth’s day has increased over geological time due to the gravitational pull of the moon on the planet’s oceans and land. However, the rapid melting of Greenland and Antarctic ice sheets, driven by human-caused global warming, is redistributing water from high latitudes into the equator-bound oceans. This redistribution makes the Earth more oblate, or “fatter,” thereby slowing the planet’s rotation and further lengthening the day.
This human-induced change is comparable to the natural processes that have shaped Earth for billions of years. Prof Benedikt Soja of ETH Zurich in Switzerland emphasized, “We can see our impact as humans on the whole Earth system, not just locally, like the rise in temperature, but really fundamentally, altering how it moves in space and rotates.”
Our reliance on atomic clocks for precise timekeeping makes this change critical. The exact duration of a day varies due to lunar tides, climate impacts, and other factors like the Earth’s crust rebounding after the last ice age’s ice sheets retreated. These variations need to be accounted for to maintain the accuracy required for internet, communication, and financial systems, as well as for satellite and spacecraft navigation.
The study, published in the Proceedings of the National Academy of Sciences of the USA, used observations and computer reconstructions to evaluate how melting ice affects day length. Between 1900 and 2000, the Earth’s rotation slowed by 0.3 to 1.0 milliseconds per century (ms/cy). Since 2000, as ice melting accelerated, this rate increased to 1.3 ms/cy. This rate is expected to remain around 1.0 ms/cy in the coming decades, even with significant reductions in greenhouse gas emissions. Without such reductions, the slowing rate could reach 2.6 ms/cy by 2100, surpassing lunar tides as the primary factor in long-term day length variations.
Dr. Santiago Belda of the University of Alicante in Spain, not involved in the research, noted, “This study confirms that the worrying loss of ice in Greenland and Antarctica directly impacts day length, causing our days to lengthen. This variation has critical implications not only for how we measure time but also for GPS and other technologies that govern our modern lives.”
The research underscores the urgency of addressing climate change to mitigate its far-reaching impacts on our planet and technological infrastructure.