James Shaw will step down as co-leader of the Green Party in March but will remain in Parliament for now.
The former Minister will stay on to support a bill which would add the right to a sustainable environment to New Zealand's Bill of Rights Act.
Shaw has been co-leader of the Green Party for nearly nine years, serving alongside both Marama Davidson and Metiria Turei.
He was also the Minister for Climate Change for six years.
Shaw spoke to Charlotte Cook.