Why some global warmth is a very good thing

Continents floating on hot molten Earth's core.

Harry Fuller Executive editor, CNET News.com
Harry Fuller escaped from television work to be executive editor at CNET News.com.
Harry Fuller
Our restless earth USGS

Got a floaty feeling? Well, it's not something you ingested and it's not your imagination. Almost all of the Earth's continents are above sea level because they float on molten material beneath the Earth's crust. That's the word from geologists at the University of Utah.

But their stunning conclusion: it's heat from inside the Earth that keeps most of North America afloat. They say the rocks of the Earth's crust are heated from beneath by molten rocks. That makes the crust not only hotter but less dense, thus it floats higher. Without this heat inside the Earth most of North America would sink below sea level. Let's hear it for geological warming.

The Utah study says New York City would be more than 1,400 feet below the Atlantic. Needless to say, New Orleans would be over 2,400 feet below sea level, and so would Miami.

One of their conclusions: it isn't the physical smashing together of tectonic plates that raises mountains. This study suggests the collision of two tectonic plates generates intense heat, which in turn makes that section of the Earth's crust more buoyant and it thus floats higher on the molten rock below. Think of the Himalayas as just some fluffy crust atop a boiling cauldron.