The glaciers are retreating, the snow is falling later and more lightly and melting sooner in the spring. If you're going skiing in the alps - TAKE THE TRAIN - it's at least ten times less polluting. And you get an extra day on the slopes...
Updates
I have to second this. Additionally, to halve the cost, don't go direct. Switch at Lille on the way out and at Paris on the way back.
Is this your business?