Activist and iwi leader Mike Smith has won the right to sue the likes of Fonterra for their role in causing climate change, in a Supreme Court ruling delivered this morning.

He wants them to either stop polluting, or start bringing emissions down quickly.

Greenpeace Executive Director Russel Norman says it means Fonterra may have to pay for some of the harm they're causing.

"Climate pollution means more cyclones and more extreme weather events, that harms a lot of people. Currently they don't pay for that, but if this court case was successful- when it goes to court, then they'd have to pay."

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