Preheat oven to 425 degrees. Place parsnips on a rimmed baking sheet and toss with 2 tablespoons safflower oil. Spread in a single layer on the pan and roast until beginning to brown around the edges, about 15 minutes. Meanwhile, combine ginger, rosemary, tamari, orange juice, and remaining safflower oil in a small bowl.
Turn the parsnips and push to edges of the pan, making space for the salmon. Add fillets, skinned-side up, to the hot pan and return pan to oven immediately. Cook until fillets are opaque on tops and bottoms and flake slightly in center when pressed, 12 to 15 minutes, flipping halfway through. Transfer salmon to plates and pour ginger dressing onto hot pan; gently toss parsnips in dressing. Divide parsnips among plates and spoon dressing from the pan onto them and fish.