A more likely scenario if humans do not significantly reduce greenhouse gas emissions, he added, would be a world in which some places disappear below sea level, many others become too hot for humans to comfortably inhabit, and hazards like heat waves, droughts and storms become more common.

Some also note that climate change data are already being recorded by scientists and other researchers.

“It’s not easily accessible or comprehensible to most people,” Daniel Kevles, a historian of science at Yale University, said of the black box. Though it may have some merit as a document for the future, he added, “I’m not all that impressed with regard to its consequential impact for warning us.”

Though the information can be found elsewhere, the creators insist, it is not stored for posterity in one immutable place.

How future visitors will be able to retrieve the contents of the box also remains unclear.

The creators say they are working on it. One option is to encode the contents in various formats, such as in script or binary code that would be unraveled. The creators say that if the planet is nearing cataclysm, instructions for opening the box would be etched on its exterior. The message can’t be included beforehand, they say, because of the risk that vandals would attempt to crack it open.

“It’s in Beta,” said Michael Ritchie, who runs a production company based in Sydney, Australia, that is managing the project. For now, “people are on notice,” Mr. Ritchie said, adding, “We want to make sure that we don’t crash this earth.”