“Most of us think a ‘green’ product is one with recyclable packaging, but the carbon footprint of shampoo is mostly in the hot water used,” says Denise Baden of the University of Southampton.

“Simple messages such as ‘most of us use too much shampoo and shampoo too often’ can prompt conversations about how shampooing less and at lower temperatures saves time, money, energy, water and is better for your skin and hair.”

[. . .]

Researchers say this demonstrates how hairdressers have an “untapped ability” to weave climate change into everyday conversations and actions.

Wow, I never thought about it like that before. If we got all the hairdressers in the world on board, that might have up to a 0.000002% impact on climate change.