Many of us have plopped down on the couch after work and thought “that was a long day,” but we probably didn’t realize that it’s likely true – just in a different way than we thought.
Recently, a group of researchers from Switzerland published two studies that show the length of a day on earth really is increasing, due to climate change. It’s a correlation that might be hard to wrap your head around, so we’ll explain.
According to the researchers from ETH Zurich, climate change is causing the ice masses in Greenland and Antarctica to melt. As they melt, the ice masses turn to water that flows from these polar regions into the Earth’s oceans, especially into the equatorial region.
“This means that a shift in mass is taking place, and this is affecting the Earth’s rotation,” explained Benedikt Soja, Professor of Space Geodesy at the Department of Civil, Environmental and Geomatic Engineering at ETH Zurich. He led the research team and their work was supported by NASA.
Soja likened the effect to a figure skater doing a pirouette, “first holding her arms close to her body and then stretching them out,” causing a fast rotation to become slower. In physics this is related to the law of conservation of angular momentum.
“This same law also governs the Earth’s rotation,” said Soja. “If the Earth turns more slowly, the days get longer. Climate change is therefore also altering the length of the day on Earth, albeit only minimally.”
In particular, the study published in PNAS showed that that climate change increasing the length of the day by a few milliseconds from its current 86,400 seconds.
However minimal this is now, as climate change and global warming continue to impact the Earth their influence on its rotational speed will become stronger. Eventually, researchers expect these influences to have a greater impact on this speed than the moon.
For billions of years, the moon’s influence on tidal friction has determined the length of our days here on Earth. Per the National Oceanic and Atmospheric Administration, coastal areas experience two high and two low tides every 24 hours and 50 minutes because the Earth rotates through two tidal bulges caused by the gravitational pull of the moon.
According to ETH Zurich, Soja’s team was able to explain fully for the first time the various causes of long-term polar motion. They also created “the most comprehensive modelling to date,” using artificial intelligence fueled methods. Included in the model is the impact of movement within the Earth and the impact of melting ice on the Earth’s axis of rotation.
Since the processes studied by the authors are linked, changes to one element, such as the axis, can impact another, such as the core. They can also impact things like precise timekeeping an
“We humans have a greater impact on our planet than we realize,” said Soja. While he said we’re not in immediate danger, he noted that the research “naturally places great responsibility on us for the future of our planet.”