Human engineering seems to have literally relocated the planet. Recent research published this month indicates that the worldwide surge in dam construction over the last two centuries has led to measurable movements of Earth’s poles. The findings suggest it has also resulted in a minor yet significant decrease in sea levels.
To fully grasp its impact on our planet, we must first examine how the Earth’s outer crust operates. The crust floats on what is essentially a layer of molten rock, allowing it to move when mass shifts across the planet’s surface. Scientists refer to this shifting as true polar wander.
While this occurrence does happen spontaneously — such as during the growth or melting of glaciers — researchers have demonstrated that human-made dams also result in the movement of Earth’s poles. A clearer way to visualize this is to think of sticking a lump of clay on a spinning basketball. As the ball rotates, it gradually adjusts to accommodate the new mass. Similarly, the outer crust of Earth readjusts itself and our geographic poles, leading to a slower drift of the planet.
This recent study analyzed data from more than 6,862 dams constructed between 1835 and 2011. Collectively, these dams hold enough water to fill the Grand Canyon twice, as noted by the researchers. Furthermore, this stored water is not merely stagnant; it actively influences our planet. These dams not only reduced the volume of the oceans (resulting in a global sea level drop of approximately 21 millimeters) but the water accumulation in these structures also led to mass shifts on land, causing the Earth’s poles to move by about 1.1 meters (3.7 feet).
The researchers pinpointed two significant phases of dam construction that have historically altered Earth’s poles. From the 1800s to the mid-1900s, dam construction in North America and Europe nudged the North Pole slightly toward Asia. However, after the 1950s, large dams in Africa and Asia shifted the pole back toward western North America. Although these movements of Earth’s poles might seem minor on a global scale, they are quite significant for our understanding of the planet and its diverse systems.
Firstly, the redistribution of water has a profound effect on how scientists predict sea level rise. Throughout the 20th century, sea levels increased by an average of 1.2 millimeters annually — but approximately a quarter of that was counterbalanced by dams retaining water on land. More crucially, the locations of stored water can alter the patterns of sea level rise. Certain areas may experience greater or lesser rises in sea level depending on where dams are situated.
This research represents just a fraction of an expanding body of evidence that human activities are fundamentally transforming Earth in significant ways. As climate change accelerates glacier melt and sea level rise, monitoring how mass moves across the planet will be essential for understanding not only our oceans but also the ongoing movements of Earth’s poles, particularly those instigated by human intervention.
