The NSW Greens will lose an MP in the upper house after Justin Field revealed he would quit the party immediately and spend the next four years as an independent on the crossbench.

Mr Field, who is midway through his term, said he did not want to spend the next four years "yelling at the government" and would prefer to work with the Coalition, not against it.

Justin Field is leaving the Greens to sit as an independent in the NSW upper house.

"This is a critical decade for climate action and reversing the decline of the natural systems that make the planet liveable. More than ever we need to build political consensus to provide for a safe and healthy future for all," he said.

Mr Field said he feared last month's election would put the Shooters, Fishers and Farmers Party and One Nation "in the box seat" to "control the agenda in this state".