by Humanity is quickly waking up to the fact that time is running out to take action to mitigate the effects of climate change. Ironically, climate change itself, primarily caused by the release of greenhouse gases through the burning of fossil fuels, may help delay a time-related crisis.
Currently, we keep official time using about 450 ultra-precise atomic clocks to keep Coordinated Universal Time (UTC), which was first defined in 1969. A more traditional historical time method uses the Earth’s rotation. But because the Earth’s rotation changes, since 1972, the alignment between these two measurements has been maintained by adding 27 “leap seconds” to the official time standard.
However, new research led by University of California geologist Duncan Agnew suggests that the melting of ice in Greenland and Antarctica due to global warming may affect the Earth’s angular velocity, the rate at which it turns. the planet, and lengthening the day accordingly, although so small it is imperceptible to humans – but not to computers that rely on accurate time.
“Global warming is already affecting global warming,” Agnew and colleagues write in a paper published in Nature on Wednesday (March 27).
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The Earth’s angular velocity is decreasing faster than before due to melting ice, which may require a “negative leap second” or leap second, taking it three years later than the scientists had hope.
The problem with this is that activities such as network computing and financial markets require the consistent, standardized and precise time scale provided by UTC, and the second negative leap has never been tested before.
“A second negative jump has never been sent or tested, so the problems it could cause are unprecedented,” wrote Patrizia Tavella, a meteorologist in the Weather Department of the Bureau International des Poids et Mesures (BIPM). the recent research in the accompanying News & Views paper. “Agnew’s suggestion that the change could be delayed is indeed gratifying.”
Tavella thinks that postponing the second negative leap from 2026 to 2029 could help meteorologists better calculate Earth’s rotation. This improved information would help better assess whether a negative second is really needed and the assessing associated risks.
The Earth is a bad timekeeper
The rate of rotation of the planet has always fluctuated, but before the introduction of timing and accurate technology, its only detrimental effect was to change the timing of eclipses and other astronomical events relative to records created and the ancient astronomers recorded.
“On a millennial time scale, changes in Earth’s rotation reflect the combined effect of all three geophysical processes,” wrote Jerry Mitrovica at Harvard’s Department of Earth Sciences and Planetarium in the Nature News & Views piece.
Mitrovica said one of these elements is the coupling between the Earth’s iron core and its rocky mantle and outer crust. This means that any change in the angular momentum of the core must be balanced by a change of equal magnitude but of opposite sign in the mantle and crust. So if the core slows down, to keep the Earth’s rotation consistent, the outer parts of the planet must speed up by the same amount. However, both the central and upper layers are losing angular momentum.
In the past, this core-maintenance coupling increased the Earth’s rotational period by 6 millionths of a second per year. Although this rate slowdown seems trivial, atomic clocks actually depend on it.
Agnew and his colleagues turned to satellite gravity data to determine the decrease in Earth’s angular momentum and its effect on timekeeping.
This showed that the increased melting of ice caps in Greenland and Antarctica changed the mass distribution of our planet’s surface and reduced the angular velocity of the Earth’s outer solid layers faster and that the angular velocity of the mostly liquid core continues to decrease consistently.
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“His analysis shows convincingly that core-mantle coupling resulted in accelerated rotation, but also significant deceleration due to the melting of the polar ice sheets that began near the end of the twentieth century,” Mitrovica wrote. “This man-made process is slowing rotation by moving a mass of melted ice from the poles to lower latitudes.”
Agnew and colleagues point out that while UTC will now not need a negative second until 2029, the problem this change creates for computer network timing requires changes to the way UTC is aligned with rotation of the Earth earlier than currently planned.
“If international timekeeping guidelines do not change soon, the numerous technological foundations of human society must be updated in preparation for this unprecedented event and for a 23:59:59 event one day in the not too distant future distant,” concluded Mitrovica. .
