TORONTO -- Former U.S. vice-president and climate change crusader Al Gore is praising Ontario's cap-and-trade system, calling it better than a carbon tax.

Gore, who is visiting Toronto and meeting with Premier Kathleen Wynne, says the way Ontario currently fights climate change is the "superior" system.

He says cap and trade lets government work directly with emmitters to cut carbon emissions over time.

Carbon pricing is shaping up to be a key issue in the province's spring election, with those vying to lead the opposition Progressive Conservatives vowing to scrap cap-and-trade and fight the imposition of a carbon tax.

Gore praised Wynne for her Liberal government's efforts to flight climate change and took a shot at Ontario's Tory leadership candidates, saying their proposals would set the province back.

Ontario's cap-and-trade system, launched last year, is aimed at lowering greenhouse gas emissions by putting caps on the amount of pollution companies in certain industries can emit. If they exceed those limits they must buy allowances at quarterly auctions or from other companies that come in under their limits.

The system has raised nearly $2.5 billion so far.