Human activity is changing Earth's tilt and rotation

Scientists have found that using underground water has more of an impact on Earth’s tilt than melting polar caps

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Even though we can't feel it, most of us are aware that our planet spins like a top during its interminable journey around the Sun..

Rather than revolving about a vertical axis, however, Earth has always been off-kilter, spinning about an axis (or pole of rotation) that's tilted at 23.44°. The amount of tilt also known as obliquity - is never constant, and displays natural short-term oscillations and longer-term cycles.

Earth's tilt can also be changed by shifting huge amounts of mass around the planet. And this is happening right now, on an extraordinary scale, due to us.

As global heating drives the melting of the polar ice sheets, it decants colossal volumes of water into the oceans. In a recent paper, scientists have revealed that this redistribution of mass is very slightly modifying the world's tilt.

But there's more. In itself, polar melting isn't sufficient to account for all of the tilt change-something else has to be happening too. The answer, the authors of the paper say, is beneath our feet.