Shaw went on to thank Greens members and supporters.
“In 2017, the Greens became a party of Government, with ministers, for the first time,” he said.
“We also made political history by increasing our support at the end of each of our two terms – a feat no other Government support partner had achieved.
“In Government, we passed the landmark Zero Carbon Act with unanimous support across Parliament, becoming one of the first countries in the world to place the Paris Agreement’s 1.5C target in national legislation.”
Shaw last year, before the election, told Newshub Nation his time as Greens co-leader was “open-ended”. He said the Greens were “not yet done… I would argue that we are only just getting going, there is so much more that we need to do”.
However, he told reporters on Tuesday he felt “my time here and my work here is complete”.
“I’m really satisfied with it,” Shaw added.
“When I first stood for the co-leadership… what I committed to was taking the Greens into Government and then safely out the other side.
“My assessment is that, actually, we are more stable… we’re doing really well right now. We’ve got a great caucus, I was really pleased with the process that we had on the other side of the election with the induction and the way that new caucus has come together.”
Shaw was first elected the party’s deputy leader in 2015 alongside Metiria Turei after Russel Norman stepped aside.
During his time in Government, he’s been a Minister of Climate Change and Statistics. Shaw said New Zealand could be “proud that it has an enduring climate change framework, with long-term targets and institutions that will guide us over several decades and changes of Government”.
“Now is the time for a new co-leader to work alongside Marama to take this new caucus into the future.”
A new co-leader was expected to be announced on March 10 with nominations open from Wednesday.
Shaw wouldn’t say who, if anyone, he’d endorse as the person to replace him. Asked if he’d put forward his support for No.3 MP Chlöe Swarbrick, Shaw said he wasn’t going to “publicly endorse any candidate for the co-leadership”.
“I’m not going to make any announcements on behalf of anybody today – that really is up to them.
“It really is up to anybody who wants to put themselves forward to make those annoucements themselves.”
Davidson also wouldn’t be drawn on whether Swarbrick could replace Shaw as co-leader.
She paid tribute to Shaw, saying she was “sad” to hear of his resignation.
“When you go through so many ups and downs together, that is a way of working together that not many team leaders ever get – so I was sad.
“I’ve had time to get over my own grief and it’s a change – so change can often be hard.
“With the election – with this incredible new caucus – I am excited,” Davidson added. “We’ve done this before, the Greens have changes of co-leaders before and he’s given blood – he’s given his life,” she said of Shaw.
“I am now happy that he gets to go to the beach.”