New Research Reveals Ancient Atmospheric Tides Kept Earth’s Rotation Steady
A team of astrophysicists from the University of Toronto has made a groundbreaking discovery that sheds light on the mystery of Earth’s day lengthening. The researchers have found evidence that from approximately two billion years ago until 600 million years ago, an atmospheric tide driven by the sun counteracted the moon’s gravitational pull, effectively keeping Earth’s rotational rate steady and the length of the day at a constant 19.5 hours.
The findings, published in the journal Science Advances, have important implications for climate change and the reliability of climate modeling instruments. The researchers used geological evidence and atmospheric research tools to demonstrate the crucial link between the atmosphere’s temperature and Earth’s rotational rate.
The moon’s gravitational pull on Earth’s oceans creates tidal bulges, which in turn slows down the planet’s rotation. This has been responsible for the gradual lengthening of our day over billions of years. However, the sun also has an impact on Earth’s rotation. Sunlight produces an atmospheric tide with similar bulges that speed up the planet’s rotation.
For most of Earth’s history, the lunar tides have been stronger than the solar tides, resulting in a slowing rotational speed and longer days. But during the billion-year period under study, the atmosphere’s temperature and Earth’s rotational rate aligned in a way that the atmospheric tide was reinforced, countering the lunar tide. This effectively paused the gradual lengthening of the day.
According to Norman Murray, a theoretical astrophysicist involved in the research, without this pause, our current 24-hour day would stretch to over 60 hours. The stability of Earth’s rotation during this period is crucial for the development and maintenance of life as we know it.
The researchers used global atmospheric circulation models, the same ones used to study climate change, to predict the atmosphere’s temperature during the studied period. This highlights the reliability of these models and provides support for their use in understanding global warming.
Murray also warns of the implications of our current warming atmosphere. As Earth’s temperature increases, the resonant frequency of the atmosphere changes, moving it farther away from resonance. This results in less torque from the sun, leading to a faster lengthening of the day.
The recent findings contribute additional perspective to the urgent issue of climate change. By understanding the intricate interplay between Earth’s rotation, atmospheric tides, and temperature, scientists can better grasp the potential consequences of global warming on our planet’s rotational stability.
Further research in this field will continue to deepen our understanding of Earth’s complex climate system and inform efforts to mitigate the effects of climate change.