"The parents need to switch their thinking to the American way. "
That’s not going to happen, they’re ingrained in their thinking.
OP- at the risk of throwing a curve to the discussion, I’d consider telling them you’ve changed your plans to be a lawyer, unless you’ve already done this. That is a profession that Indian parents born in India will acknowledge has money, influence and prestige in the US (lawyer jokes aside). I’d also change major to poly sci (a lot of overlap with govt) and mention that in these times, that could be a good degree on its own. And emphasize the science part of poly sci, the courses in theory, models etc… Consider a minor in stats if you want to show you’re going to have some analytical skills. If they agree to all this, you may have to give up on the environmental stuff as part of the compromise, Or you’ll have to do as a “silent” minor, as others have suggested, almost in stealth mode, don’t bring that up. Then see what happens in three years. Good luck.