The McGowan government has confirmed it will enshrine the 2050 target in legislation to be introduced to parliament this year.

It will include a goal of reducing government emissions by 80 per cent below 2020 levels by the end of this decade.

Environmentalists have welcomed the plan but questioned why interim reduction targets have not yet been outlined for the broader economy.

"A net-zero 2050 target is a good starting point but the key to this new legislation will be setting adequate five-yearly interim emissions targets," the Conservation Council of WA's Maggie Wood said on Tuesday.

"Polluters must be compelled to make meaningful cuts to their emissions as quickly as possible if we are to avoid the worst extremes of climate change.

"The amount of progress we make in this decade will be crucial."

Describing climate change as the greatest challenge of our lifetime, Environment Minister Reece Whitby said the plan would provide certainty, stimulate investment in renewable energy and require annual reporting to parliament on the state's progress.

He said further consultation was needed to establish interim reduction targets which would be set at least five years in advance.

"This is about what is realistic and responsible," Mr Whitby told reporters.

"We're a state which has a lot of fossil fuel companies and a lot of mining companies and that means we have high emissions, so we've got a particular challenge in Western Australia."

WA is the only state which has recorded an increase in emissions on 2005 levels.

NSW is targeting a 70 per cent reduction by 2035, while Victoria and South Australia want to achieve a 50 per cent cut over that period.

Individual emitters will not be penalised for failing to reach targets with Mr Whitby stressing it was an economy-wide plan.

He said WA's environmental watchdog already required proponents to have a viable pathway to net-zero to get projects approved.

"There's no free pass to everyone. Everyone has to pull their weight," he said.

"The big emitters have big challenges but they still need to have a realistic path to net-zero."

Environmentalists believe the development of massive oil and gas projects such as Woodside's Scarborough will jeopardise WA's decarbonisation efforts.

Greenpeace Australia campaigner Jess Panegyres said transitioning away from such projects needed to be an urgent priority.

"WA has incredible opportunities in the clean energy economy," she said.

"The continued expansion of the gas industry is short-sighted and will undermine WA's ability to meet this important goal."

Australian Associated Press