Earth Is Getting Rounder-and You Can Guess Why

Key Points:

• Earth is not a perfect sphere but an oblate spheroid, bulging at the equator and flattened at the poles; recent research shows that climate change is causing the planet to become rounder at an accelerated rate.
• A study published in JGR Solid Earth found that polar ice melt and redistribution of meltwater are causing the poles to rise by about 0.5 to 1 millimeter per year and the equatorial bulge to shrink at a similar rate, with these changes accelerating over recent decades.
• The melting of polar ice reduces pressure on Earth's crust at the poles, causing uplift, while increased meltwater at the equator adds pressure, causing subsidence, leading to a measurable change in Earth's shape.
• Although these shape changes are small relative to Earth's size, they reflect significant human-driven impacts on the planet's physical characteristics, including its axis, rotation, and gravitational field.
• The study emphasizes the profound influence of fossil fuel-driven climate change on Earth's fundamental properties, though these shape changes do not pose immediate threats to life.