Brisbane would become a net zero emissions city by 2050 through improved public transport, building efficiency and green space, under a proposal by Labor's lord mayoral candidate, Pat Condren.

The plan would see Brisbane City Council become "truly" carbon neutral, with projects to do so singled out for the first 100 days of an elected Labor administration, and $27.5 million earmarked for its first four years to begin carrying them out.

Labor plans to make Brisbane City Council "truly" carbon neutral if elected in March. Credit:Darren England/AAP

A total of $5 million to green King George Square and an extra $1.8 million for tree planting across the city would also "kick off" the plan, to be announced on Friday ahead of the March 19 election.

"Brisbane City Council as an organisation needs to lead the way for our city to become truly carbon neutral," Mr Condren said.