Unconstrained by diplomacy, I would put it this way: If we insist on ruining the planet, we can no longer call ourselves the most intelligence species. We have the tools, but we're not fully using them. We know what to do, but we're not doing it.
For decades, our collective "ecological footprint" has exceeded what the Earth can sustainably provide, now by over 50 percent. This may be our last best chance to deal seriously with the global environmental crisis before it is too late.