Arnold Schwarzenegger and Opposition Leader Bill Shorten are set to discuss climate change in Melbourne.

The former California governor and Terminator star is in the city this weekend for the Arnold Classic, an annual multi-sport festival which features body builders.

Schwarzenegger and the opposition leader will meet on the sidelines of the special kids expo for the event at the Melbourne Convention Centre this afternoon.

Mr Shorten praised Schwarzenegger's track record in the fight against carbon pollution.

“Anyone who's seen his work knows he's a straight-shooter determined to save the planet," Mr Shorten said.

"He sticks to his principles, even when the going gets tough."

California's economy is the sixth largest in the world - a feat achieved in part because it is an attractive and stable environment for renewable energy investment, Mr Shorten said.

The Turnbull government has repeatedly attacked Labor over its policy to establish a target of 50 percent renewable energy by 2030.