The NHL is pledging to turn down the lights this weekend.
The league plans to observe Earth Hour on Saturday evening, with all 30 teams having committed to scaling back the energy used in their arenas between 8:30 p.m. and 9:30 p.m. local time.
There are 10 games scheduled that evening.
The NHL says all non-essential lighting in its arenas will be turned off.
The World Wildlife Fund started Earth Hour five years ago in Australia and has seen it grow to become the world's largest global climate change action.