Reformed theology is a vision of God’s sovereignty over the planet that he made. He has an eternal purpose for it and he is not going to throw it away on the trash heap of the universe.
When 2 Peter 3 talks about the universe being burned up, I don’t think it means "junk that universe, let’s start over with another one." I think it means "cleansed" like a forest fire might cleanse Mount Saint Helens, and bang it is glorious again. He can shorten that down to minutes rather than decades.
This universe we live in is God’s. He made it and he made it good. It’s a mess right now both in sin and in catastrophes, and it isn’t always going to be this way. It is going to turn around someday. We are living on a planet in a universe that is going to always be here, and God will renew it. So it matters to him that we care for it. That’s one set of arguments.
The more important argument (neither of these arguments are unique to reformed theology) is loving our neighbor as we love ourselves. I don’t think the argument from the fact that this earth is going to be renovated someday is the best argument for why you should care about clean water. You care about clean water because you love your neighbor and your grandkids and people in general. You want to reduce suffering.
The way I talk about our commitment at Bethlehem to physical, social, and spiritual things is, I want us to care a lot about and work toward eliminating suffering—especially eternal suffering. That’s the order.
Suffering like, you drink this water and you get dysentery and you die. Well, let’s fix that if we can. If you release garbage from your city and it all goes into the river downstream, all the fish die, and the ecological thing gets all broken out of joint. Well, go do some filtering upstream.
I think the best argument for environmental concern is love for people, not love for mother earth. Who cares about mother earth as a mother? The earth is the Lord’s and the fullness thereof. It’s his and he meant it to serve people. He put us here to enjoy it. So, if we mess it up we are hurting people.
Those two things (the earth is going to be here forever and God cares about it, and loving people means you should care about how the environment hurts them) are why I think reformed theology (and other kinds of theology) teaches us to care for our environment.