Climate change is messing with time
“The melting of polar ice due to global warming is affecting
Earth’s rotation and could impact on precision timekeeping,
according to a recent study.
The planet is not about to jerk to a halt, nor speed up so
rapidly that everyone gets flung into space. But timekeeping
is an exact science in a highly technological society, which is
why global authorities more than half a century ago felt
compelled by the slight changes in Earth’s rotation to invent
the concept of the ‘leap second’.
Climate change makes these calculations even more
complicated: Soon it may be necessary to insert a ‘negative
leap second’ into the calendar to get the planet’s rotation in
sync with Coordinated Universal Time.
Timekeeping is based on an astronomical basis. Earth is a
type of a clock. In simpler times, the planet would spin one full
revolution on its axis, and everyone would call it a day.
But Earth doesn’t spin at a perfectly constant speed. Our
planet is in a complicated gravitational dance with the moon,
the sun, the oceanic tides, Earth’s own atmosphere and the
motion of the planet’s solid inner core.
The planet’s fluctuating spin rate is carefully tracked by the
International Earth Rotation and Reference Systems Service.
In the early 1970s, Earth was clearly slowing down in its
rotation, and a gap was forming between atomic time and
astronomical time. Thus, was born the ‘leap second’ to adjust
for the fact that the ‘day’ was getting a bit longer.
The melting of the ice caps in Antarctica and Greenland
shifts mass — meltwater — toward the equator. That process
increases the equatorial bulge of the planet. Meanwhile, at
the poles, the land that had been pressed down by ice rises,
and Earth becomes more spherical.
According to the study, although the core is causing the
planet to spin faster, the planetary shape changes caused by
a warming climate are slowing that process. Absent this
effect, the overall acceleration of the planet’s rotation might
require timekeepers to insert a ‘negative leap second’ at the
end of 2026. Because of climate change, that might not be
necessary until 2029.”
Disponível em https://www.washingtonpost.com/science/2024/03/27/
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