[pdubs1]

Your logic is faulty.

> "the mass die-offs we're seeing are because the world's coral reefs will be dead by 2050"

This does not make sense.

Let's break it down:

This is what you're saying:

"The [current thing happening] is due to [the occurrence of a future thing]."

Clearly, something in the present is not due a dependency on an event which has not happened yet.

What you should perhaps say is something more like:

"The [current thing happening] is due to [the same causality] as what will cause/is causing [the future occurrence]."