It has happened twice in July, it will repeat itself. Is that the earth is turning faster and scientists are evaluating what to do
Earth is turning faster: scientists evaluate unprecedented action
by Jacopo PriscoCNN
The earth is turning faster this summer, making the days slightly shorter and attracting the attention of scientists and who timates time.
July 10th has been the shortest day of the year so far, lasting 1.36 milliseconds less than 24 hours, according to data from the Earth’s International Rotation Service and the US Naval Naval Observatory, compiled by the site. This Tuesday we had a day with less than 24 hours and will happen again to August 5: Tuesday was 1.34 milliseconds shorter than 24 hours and on August 5 will be and 1.25 milliseconds.
The duration of one day is the time the planet is slow to complete a complete rotation on its axis – 24 hours or 86 400 seconds, on average. But in fact, each rotation is slightly irregular due to a number of factors, such as the gravitational force of the moon, the seasonal changes in the atmosphere and the influence of the earth’s liquid nucleus. As a result, a complete rotation usually takes a little less or a little over 86,400 seconds – a discrepancy of only milliseconds that has no obvious effect on daily life.
However, these discrepancies can, in the long run, affect computers, satellites and telecommunications, which is why even the smallest deviations are controlled through atomic watches, which were in 1955. Some experts believe this can lead to a scenario similar to the Y2K problem, which threatened to stop at
Atomic clocks count on the oscillations of the atoms within the clock itself to calculate 24 hours with the maximum degree of precision. We call the resulting time UTC, or coordinated universal time, which is based on and is the worldwide standard for time counting, as well as the time for which all our phones and computers are configured.
Astronomers also accompany the earth’s rotation – using satellites that check the planet’s position in relation to fixed stars, for example – and can detect minimal differences between atomic clock time and the time the earth really leads to complete rotation. Last year, on July 5, 2024, Earth lived the shortest day ever recorded since the advent of the atomic clock 65 years ago, with 1.66 milliseconds than 24 hours.
“Since 1972, a tendency for slightly faster days has been registered,” says Duncan Agnew, emeritus geophysics professor at the scripps institution of Oceanography and a geophysical researcher at the University of California, San Diego, USA. “But there are fluctuations. It’s like watching the action market. There are long -term trends and then there are peaks and falls.”
In 1972, after decades of relatively slow rotation, Earth’s rotation had accumulated such a great delay in the atomic time that the Earth’s international rotation service and reference systems required the addition of a “second leap” to UTC. This is similar to the leap year, which adds an extra day to February of four years to take into account the discrepancy between the Gregorian calendar and the time the earth is slow to complete an orbit around the sun.
Since 1972, UTC have been added to a total of, but the pace of addition has been slow due to the acceleration of the earth; Nine seconds were added throughout the 1970s, but no new bisextal seconds have been added since 2016.
By 2022, the General Conference on Weights and Measures (CGPM) in favor of eliminating the second leap by 2035, which means that a second one will never be added to the clocks. But if the earth continues to rotate faster for a few more years, according to Agnew, it may eventually be necessary to remove a second from UTC. “There has never been a second negative interchange,” he says, “but the probability of having one between now and 2035 is about 40%.”
What is making the earth rotate faster?
Short -term changes in earth rotation, Agnew, come from the moon and the tides, which make her turn more slowly when the satellite is over the equator and faster when he is at higher or lower altitudes. This effect is aggravated by the fact that during the summer, the earth rotates naturally faster – the result of the slowdown of the atmosphere itself due to seasonal changes, such as the displacement of the jet current to north or south; The laws of physics dictate that the global angular moment of the earth and its atmosphere must remain constant, so the speed of rotation lost by the atmosphere is recovered by the planet itself. Similarly, the last 50 years the earth’s liquid core has also been slowing down, while the solid earth around it is accelerating.
By analyzing the combination of these effects, scientists can predict if one approaching day may be particularly short. “These fluctuations have short -term correlations, which means that if the earth is accelerating one day, it also tends to accelerate the next day,” says Judah Levine, a physicist and member of the National Institute of Standards and Technology in Time Division and Frequency. “But this correlation disappears as it advances to increasing intervals. And when one year is reached, the forecast becomes quite uncertain. In fact, Earth’s international rotation service and reference systems does not make predictions more in advance than one year.”
Although one day less makes no difference, says Levine, the recent trend of shorter days is increasing the possibility of a second negative leap. “When the system of second interchange was defined in 1972, no one thought that the second negative would exist,” he notes. “It was just something that was included in the standard because it had to be done to be complete. Everyone supposed that it would only be needed positive bisexcts, but now the shortening of days makes (seconds negative bisextes) risk happening, so to speak.”
The perspective of a second negative leap arouses concerns because there are still problems with positive bisexts after 50 years, explains Levine. “There are still sites that do it badly or do it at the wrong time – or who do it with the wrong number and so on. And this is with a second positive leap, which has been done times without account. There is a much greater concern with the second negative interim, because it has never been tested, has never been experienced.”
Since many fundamental technological systems depend on clocks and time to work, such as telecommunications, financial transactions, electrical networks and GPS satellites, just to name a few, the advent of the second negative leap is, according to Levine, something similar to the problem of Y2K – the moment when the world was to be done to be a kind of judgment day because the computers could not achieve because computers could not succeed because computers could not succeed because computers could not succeed Negotiate the new format of the date from “99” to “00”.
THE ROLE OF DEGELO
Climate change is also a factor that contributes to the issue of the second interspersing, but in a surprising way. Although global warming has had considerable negative impacts on Earth, with regard to our timing, it served to counteract the forces that are accelerating the rotation of the earth. A study published last year by Agnew in the magazine describes in detail the way the ice that melts in Antarcecid and Granelândia is spreading across the oceans, slowing the spinning of the earth – like a skater that spins with his arms over his head but slows down if the arms are bent along the body.
“If the ice had not melted, if we had not had global warming, we would already have a second negative leap, or we would be very close to having it,” says Agnew. , the melted water of the Granelândia and Antarcticide ice sheets is responsible for one third of the overall rising sea level since 1993.
The mass change of this melted ice is causing changes not only in Earth’s speed of rotation, but also in its axis of rotation, according to an investigation led by Benedikt Soja, assistant professor at the Department of Civil, Environmental and Geomatic Engineering at the Swiss Federal Institute in Zurich, Switzerland. If heating continues, its effect can become dominant. “By the end of this century, in a pessimistic scenario (where human beings continue to emit more greenhouse gases), the effect of climate change could exceed the effect of the moon, which has actually boosted Earth’s rotation in the last thousands of millions of years,” says Soja.
At this time, having more time to prepare the action is useful, given the uncertainty of long -term forecasts on Earth’s rotation behavior. “I think the fastest rotation is still within reasonable limits, so it can be a natural variability,” says Soja. “Maybe in a few years we can again watch a different situation and, in the long run, the planet can slow back. That would be my intuition, but it is never known.”
