Any number of MacGuffins or standard scifi tropes would likely do, to serve as impetus from otherworldly conquerers. But this story gave me a pretty good idea as to why aliens in GWW might have reason to take over our planet--and not care if the surface was scorched clean by death rays. As it turns out, the Earth may hold up to three times more water reserves than previously thought--deep underground.
|The V mini-series from the 80s was right all along!|
The water is locked up in a mineral called ringwoodite about 660km (400 miles) beneath the crust of the Earth, [emphasis mine] researchers say. Geophysicist Steve Jacobsen from Northwestern University in the US co-authored the study published in the journal Science and said the discovery suggested Earth’s water may have come from within, driven to the surface by geological activity, rather than being deposited by icy comets hitting the forming planet as held by the prevailing theories.So the Earth is, in fact, an even bigger source for water in the solar system. Not to mention the fact that the reserves could be inspiration for the "great cataclysm" itself. It makes sense, from a narrative standpoint why the subterranean-dwelling valids would want to jealously protect the Earth's remaining, untouched resources.
“Geological processes on the Earth’s surface, such as earthquakes or erupting volcanoes, are an expression of what is going on inside the Earth, out of our sight,” Jacobsen said.
What more can I say, science is cool!