Victoria Dam, Sri Lanka
Over the past two centuries, humans have accumulated enough water in dams to slightly move the Earth’s poles away from the planet’s axis of rotation.
The outer solid layer of the earth rests on viscous rockso it can move on the magma below.
Whenever the mass is redistributed around the planet’s surface, as when the ice layers grow or shrink, this outer rock layer oscillate and move.
A new one, recently published in Geophysical Research Lettersfound that the construction of almost 7,000 dams Between 1835 and 2011 shifted the poles about one meter in total, and caused a decrease of about 21 mm at the global level of the sea – 1/4 of the expected climb in the twentieth century.
Together, these dams contain about 8.3 billion liters of water – an amount equivalent to the Amazon River dumps in the ocean for a year, and sufficient to supply the entire world population for 1,400 years.
Imagine we shot a piece of clay to one side of a rotating soccer ball: to maintain the momentthe part of the ball with the clay will move slightly towards its equator and move away from its axis of rotationexplain the authors of the study in a published in AGU.
When this happens on the earth and the outermost rock layer oscillates, different areas of the surface They end up being directly on the axis of rotation. Geographical poles then pass through different points on the surface – a process called True Polar Deriva.
The results of the study show once again how human activities can affect our planet. The polar displacement is smallbut it can help scientists understand how poles will move if the main glaciers and layers of ice melt due to climate change.
“When we retain water behind dams, Not only do we remove water of the oceans, thus leading to a global fall of sea level, as we also distribute mass differently around the world, ”he says Natasha Valencicresearcher at Harvard University and main author of the study.
The study shows that the change took place in two phases: From 1835 to 1954, dams in North America and Europe pushed the pole toward Russia and China. Between 1954 and 2011, dams in Asia and East Africa redirected him Back to North America and the South Pacific.
Although the movement of the pole will not properly trigger a glacial era, these changes influence sea level geometry.
“Let’s not get into a new glacial era“, Says Valencic.“ But the way water moves – or not – can reshape our planet in ways we are just starting to understand ”.
