Earth is becoming more rounded as polar ice melts, with rising poles and shrinking equatorial bulge, revealing climate change's impact on the planet's shape.
Earth's shape changing due to melting ice
Direct satellite measurements show that Earth is becoming more rounded as polar ice caps melt due to climate change. This process has accelerated since the 1990s, despite Earth's long-term flattening caused by its rotation.Historical factors shaping Earth
Since its formation, Earth’s shape has evolved due to various factors, including crust and mantle movements, as well as its rotation. These factors contribute to Earth being slightly flattened at the poles and bulged at the equator.Impact of melting ice on Earth's form
The melting of polar ice caps and glaciers can alter the distribution of water masses, influencing the planet's shape. Climate projections suggest glaciers could lose 25 to 29 percent of their volume by 2100 in a low-emission scenario, and up to 46 to 54 percent in a high-emission scenario.Tracking Earth's shape changes
A study at Aristotle University of Thessaloniki proposes using GNSS data to estimate Earth’s flattening. Researchers found that polar regions are rising slightly, while the equatorial bulge decreases by about 1 millimeter per year between 2011 and 2015.Limitations and improvements in data collection
GNSS data allow observation of Earth's surface movements but have uneven global coverage, especially in polar and remote areas. Researchers developed a method to better analyze these data and track Earth's shape changes.Acceleration of Earth's shape changes
The rate of Earth's flattening has increased compared to previous decades. Between 2011 and 2015, the decrease in flattening was about 1 millimeter per year, compared to 0.5 millimeters per year between 1997 and 2000.Mechanisms behind Earth's shape changes
The melting of polar ice reduces pressure on the Earth’s crust, causing the ground to rise. This is similar to elastic dough regaining its shape after being pressed. Water redistribution to equatorial regions also affects the Earth's crust and gravitational field.Non-uniform responses to mass redistribution
The changes in Earth's shape do not fully correspond to changes in its gravitational field. This indicates that the Earth's response to mass redistribution varies depending on mass distribution and geophysical factors.Climate change's direct impact on Earth
These observations highlight the direct effects of human-induced climate change on Earth's physical shape. Monitoring these changes can provide insights into how human activities affect ice caps and the planet’s long-term behavior.
