Mars could have a devastating sea level rise.

A spacecraft orbiting Mars has scanned huge deposits of ice at its south pole so plentiful they would blanket the planet in 36 feet of water if they were liquid, scientists said on Thursday.

The scientists used a joint NASA-Italian Space Agency radar instrument on the European Space Agency Mars Express spacecraft to gauge the thickness and volume of the ice, which covers an area larger than Texas.

The deposits, up to 2.3 miles thick, are under a polar cap of white frozen carbon dioxide and water, and appear to be composed of at least 90 percent frozen water, with dust mixed in, according to findings published in the journal Science.

And that ain't the half of it.

Dr. Plaut, part of an international team of two dozen scientists, said a preliminary look at this data indicated the ice deposits at the north pole were comparable to those at the south pole. . .

Dr. Plaut said the amount of water in the Martian past might have been the equivalent of a global layer hundreds of meters deep, while the polar deposits represent a layer of perhaps tens of meters.

“We have this continuing question facing us in studies of Mars, which is: where did all the water go?” Dr. Plaut said.

“Even if you took the water in these two ice caps and added it all up,” he said, “it’s still not nearly enough to do all of the work that we’ve seen that the water has done across the surface of Mars in its history.”

Blown away by solar wind? Mined by aliens? Still there but under the surface? Fiction fodder.