The supreme court has absolute discretion regarding which cases it takes, and someone is always bringing new cases about pretty much every controversial issue in the hope that the supreme court will decide to take one of them. Then in theory the court rules according to the constitution, but there are enough different interpretations that one can be found to support almost any decision. Congress is too divided to override any decision that isn't literally insane.

I think the supreme court still spends most of its time doing what it is intended to do, but it has also become an instrument for making dramatic changes to the law while congress is too divided to do so. (Or else why would the political affiliation of the president nominating a new judge matter so much?)

But with all that out of the way, the point I'm trying to make is that it isn't unreasonable for the DOJ to argue that the constitution doesn't say anything about the climate when that is literally true. Maybe the court will rule that the constitution implies something related to climate change (although I wouldn't bet on that) but some commenters here are claiming that the DOJ is being ridiculous and I think these commenters are failing to make the is-ought distinction.