Graffiti

"I have set before you life and death, blessing and curse; therefore choose life"

— Moses

You may consider the discs 's to be the earth's self-healing tablets against the “human”-pleague. 

Their placement at the bottom of melting glaciers and under mass eroding topsoil most probably does not come accidentally. And whoever has placed those disques must have had a plan. And this plan says, “Stop every civilization that might have caused extreme climate change the same way as other civilizations were stopped before: Atlantis, Lemuria, Noah's Land, the Paradise, etc.

However, this plan came with some mercy built in. 

The destruction of humanity does not start automatically on its own but only by human beings fully aware of the consequences of what they are doing and morally rotten and immature enough to use such powerful mechanics for their own, egoistic advantage, and so starting a chain reaction that only can be halted—mercy point again—by global, ubiquitous intelligent collaboration.

The clever part is , that none of these discs contained all the information to build and execute the ferroconcrete dissolving mechanism but had to “come” together with at least some others, not physically by setting them just near to each other, neither for interaction nor to conclude from their shared “patterns” on their surface (which finally has not turned out to be of any relevance and just served for some kind of identification) but indirectly by scripting their energy, message or whatever you want to call it into their sourrounding water. 

And when such informed water came rinsing and floating down the rivers into the deep ocean, and when their individual structures finally united like a self-solving puzzle, the such created molecular-structure started spreading again river up to the sources where it was drunk or was bathed in and so has “imprinted” the detailed  imagination of the graffitties onto human brains, so that when this “idea” for a graffiti was applied on ferroconcrete walls, building or streets, have started their immediate dissolution upon some not yet known quantum-entanglement effects.