Thirty-two out of 107 delegates voted at the party's online annual general meeting today to vacate Shaw's position, more than the 25 percent threshold necessary under the Greens' rules.
The vote means any Green Party member can now put their name forward for the role over the next week before another vote within five weeks.
Speaking at Parliament this evening, Shaw said he was "inclined" to stand again, but would first seek feedback from his caucus colleagues and the wider membership.
"This is obviously a bit of a surprise. I've got to work through a few things," Shaw said.
"I still got 70 percent of the delegates supporting me and I've had quite a lot of supportive messages in the very brief time that the news has been out. But I do want to take some soundings just to get a proper sense check."
Shaw said he was still processing the outcome and would spend some time with his family tonight.
"It is hard when there is a group that's organising against you. But... I have been so focused on my job as Minister for Climate Change, doing what we need to do to fight the climate crisis, that I really don't have a lot of time for factional organising."
Co-leader Marama Davidson - who was reconfirmed by delegates - said she was personally shocked by the action against Shaw.
"I certainly wasn't expecting this," Davidson said. "I feel saddened for my friend, as you would feel for anyone who loses their title and role at this time."
Davidson, though, declined to give a full-throated endorsement of Shaw staying on, saying she would not pre-empt his decision or the party's. She did say Shaw had "slogged his guts out" in the role.
"I'm simply here to support the work that James has done to date... we've been able to keep our support quite well above our election night support numbers."
Shaw said he had spoken to Prime Minister Jacinda Ardern this afternoon and she had confirmed he would retain his position as Climate Change Minister regardless of the leadership decision.
"This is a temporary blip. It does not have any impact on the work that we're doing as ministers or the work of our MPs," Shaw said.
The party caucus would meet as usual on Tuesday morning with no current plans to meet before then.
The Green Party constitution was recently changed meaning Shaw's position could be filled by a person of any gender.
Shaw was elected to the party's leadership in 2015 after Russel Norman announced his retirement.
Last year, Shaw comfortably defeated a challenge to his co-leadership from activist James Cockle. In that contest Shaw received 116 votes to Cockle's four.
by Craig McCulloch
