But that's precisely how it's supposed to work. That there is not (yet) sufficient political will to adopt these policies by statute does not in any way create

But that's precisely how it's supposed to work. That there is not (yet) sufficient political will to adopt these policies by statute does not in any way create a duty for the judiciary to act. Congress makes the laws. It's the judiciary's job to interpret them. At least so far, there is no law (in the US) with a generic obligation to protect future generations from environmental harm. I question how such a law could even work given that a great deal of human activity permanently alters the natural environment.