While it feels like we’re standing very still and stable when we’re sitting idle or standing, Earth is actually spinning at around 1,000 miles an hour.
This concept may make Earth sound like an unstoppable force, as trying to slow down something spinning at 1,000 miles an hour that weighs thirteen septillion pounds seems impossible. However, NASA has recently shared some surprising and cool findings – megastructures can affect the rotation speed of Earth!
China’s Three Gorges Dam is an enormous structure, but the key to its impact on the Earth’s rotation speed lies in how much water it can hold.
Three Gorges Dam
The Three Gorges Dam has a reservoir that holds nearly 40 billion cubic meters of water. This amount of water in one place redistributes Earth’s mass and increases its moment of inertia, which resists rotational change.
In a fascinating study, NASA has confirmed that this redistribution of weight has lengthened each day, albeit by a minuscule amount at 0,06 microseconds.
This amount of time is incomprehensible to humans, but it does prove that large-scale engineering projects can have an impact on an otherwise seemingly all-powerful and immovable force like the Earth’s rotation.
Historical Context
The rotation of the Earth has changed in the past over long periods when massive events have shifted the distribution of water and land on Earth.
The processes of continents shifting would take millions of years and change Earth’s rotational speed slowly, but now, we’ve found that we can do it in just decades if a big enough dam redistributes enough water.
Once the Three Gorges Dam was built in 2012, scientists took note of how it affected Earth’s rotation. This new kind of impact that humans are having on the Earth is a fascinating one, as most people didn’t think we could change the length of days, no matter how small.
Why Big Dams Matter
To better understand this concept, think of Earth as a figure skater spinning. When the skater puts out their arms, they will spin slower. With the Three Gorges Dam retaining 40 billion tons of water, it’s like it’s stretching out its metaphorical arms.
This much water being farther from the center slows down the rotation by a fraction, but enough to be measurable to scientists who strive to find every conceivable impact that we are having on the planet.
This isn’t the first case of a man-made structure changing the Earth’s rotation.
Other Human Impacts
There are other structures on Earth that have affected Earth’s rotation. Pumping groundwater and redistributing lakes by draining them and moving the water elsewhere in the world has had an impact on the Earth’s axis by about 80 centimeters since 2000.
Other changes to the Earth have had an even larger impact on the length of days than that of the Three Gorges Dam. The Aral Sea in Central Asia’s sinking has slowed the Earth’s spin, and everything mentioned is all contributing together to make days longer.
Even with all of these factors, the amount of extra time in a day is still unnoticeable without scientific measurements.
What This Means Globally
Three Gorges Dam isn’t going to be the last dam that China built. They are going to build even bigger dams that are part of their global development plans.
If each of these dams has a similar impact on Earth’s weight distribution, like the Three Gorges Dam, then these could add up over time, but it would take millions to make days conceivably and problematically longer.
If this ever did occur, global clocks would have to be adjusted to account for the extra time in a day, showcasing that local construction could theoretically have worldwide time affected.
An Environmental Impact
Longer days could have unexpected and unprecedented effects on global wildlife. Historically, major rotational slowdowns have coincided with dramatic evolutionary events.
Changes in day length would alter the cycles of light and darkness, which could potentially disturb animal behaviors, such as bird migration, predator hunting, and animal reproduction.
Temperature patterns would also change, impacting everything from food availability to plant growth. Some species could be favored during these shifts while others could be pushed towards extinction, showcasing the real impact we could have if we manage to change the rotational speed of the Earth enough.
The Future
As China and other nations look towards hydroelectric power, the effect on the Earth’s rotational speed could become more noticeable.
With climate factors melting the ice at both poles, further weight will be redistributed on Earth, all playing a part that could make days noticeably longer in the future. This is a big deal that impacts everyone, from global nations to local communities.
Longer days could be fixed via a change in clocks, but there could be other implications for faster-rotating Earth that scientists are yet to discover.
What Could Be Done?
If enough dams are being built in the future to have a real impact on the Earth’s rotational speed, there are solutions to counteract the effects. If engineers could track how the distribution of water affects the rotational speed, then water could be adjusted and managed accordingly.
Dams could change when and how much water they release, coordinating with other dams to reduce their impact.
Governments could pass legislation that require huge projects like these have to study the potential impacts on Earth’s rotational speed.
Opening Our Eyes
The Three Gorges Dam has opened our eyes to a fascinating concept that many didn’t know was possible. Humans have the power to change time – in a sense.
The size of the effect on Earth’s spin may be an inconsequential metric right now, but it proves that we can still have an impact, and it could get larger in the future.
As urbanization and industrial efforts continue to expand in every nation, we need to balance the impact we have with the effect on the environment.
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