Nations that changed from the Axis powers to the Allies
The biggest hydroelectric project in the world, the Three Gorges Dam, sits on the Yangtze River in the Hubei province of China. It took decades to build and, despite its incredible capacity for power generation, it has been shrouded in controversy. From an increased risk of landslides, to the displacement of local residents, many have found something to complain about when it comes to the Three Gorges Dam.
One topic that has left people scratching their heads, however, is the dam's potential ability to change the length of our days. Curious? Check out this gallery to find out more.
Located along the Yangtze River in Hubei province, China, the Three Gorges Dam is the largest hydroelectric project in the world.
It was no mean feat to build: standing at 2,335 meters (7,660 feet) long and 185 meters (607 feet) high, it was completed in 2012 after nearly two decades of construction.
It was also designed to increase shipping capacity on the Yangtze River and to provide flood storage space, thereby reducing the potential for flooding downstream.
Historically, the Yangtze Plain has struggled with flooding. In 1931, for example, floods on the river caused the deaths of four million people.
In general, China considers this major hydroelectric project to be a success. Indeed, it has state-of-the-art turbines and is moving towards limiting greenhouse gas emissions.
However, it has also caused significant environmental, social, and ecological changes, some of which have sparked controversy both in China and worldwide.
On the one hand, the building of the Three Gorges Dam required huge numbers (roughly 1.5% of the Hubei population) to be displaced.
On the other hand, experts have also expressed concerns about an increased risk of landslides and interruptions to surrounding wildlife, in particular endangered species.
Perhaps the most curious impact of the Three Gorges Dam, however, lies in its potential power to alter the Earth's rotation.
This topic was first raised in a 2005 NASA post, where geophysicist Benjamin Fong Chao drew attention to the fact that the dam holds enough water to shift the distribution of the Earth's mass.
When you consider that the distribution of an object's mass impacts its rotational speed (the principle of moment of inertia), this suggests that the dam could also impact the Earth's rotational speed.
Indeed, Chao calculated that due to its size, the reservoir of the Three Gorges Dam could increase the length of a day by approximately 0.06 microseconds.
In addition, it could also make the Earth slightly more round in the middle, and slightly flatter on the poles.
While these changes may seem tiny and insignificant, they do serve as a reminder, as Chao mentioned, that human engineering can have a planet-scale impact.
However, human engineering is not the only factor that can influence the Earth's spin. For years now, NASA scientists have been looking at how natural disasters can impact the Earth's rotation.
In fact, according to NASA research, this single extreme weather event shortened the length of a day by 2.68 microseconds. That's considerably more than the Chinese dam would lengthen a day by.
Climate change is another factor that influences the Earth's rotation by serving to redistribute its mass.
As global temperatures increase, polar ice caps melt and sea levels rise. As a result, an increasing volume of water is accumulating near the equator.
This results in a changing distribution of mass, which could, in theory, slow down the Earth's rotation.
Until now, these changes to the Earth's rotation have been so tiny that they are imperceptible and irrelevant to daily life. However, that may not always be the case.
Already, experts are talking about a need to recalibrate time-keeping mechanisms that are used for ultra-precise measurements, such as atomic clocks.
Indeed, although it may seem trivial, the cumulative effect of timekeeping errors could impact modern technologies, such as GPS systems and satellite communications.
Some scientists have even called for a "negative leap second" (i.e. a minute with 59 rather than 60 seconds) to be introduced in the next few decades.
The idea is that the extra second would compensate for the gradual and cumulative changes in day length as a result of natural disasters or man-made structures.
For now, it seems clear that the Three Gorges Dam is not impacting our day length in any meaningful way. It does serve as a reminder, however, of the way in which human engineering impacts the Earth.
Sources: (Firstpost) (Business Today)
See also: China's magnificent city of ice
The huge dam in China that is making our days longer
The terrestrial impact of the Three Gorges Dam
LIFESTYLE Science
The biggest hydroelectric project in the world, the Three Gorges Dam, sits on the Yangtze River in the Hubei province of China. It took decades to build and, despite its incredible capacity for power generation, it has been shrouded in controversy. From an increased risk of landslides, to the displacement of local residents, many have found something to complain about when it comes to the Three Gorges Dam.
One topic that has left people scratching their heads, however, is the dam's potential ability to change the length of our days. Curious? Check out this gallery to find out more.