TORONTO -- Ontario's first cap-and-trade auction sold out all current allowances, giving the new market a strong start, but the province's environment minister warned the real test of the system will be in the emission reductions it brings about.

The March 22 auction brought in $472 million, the government said Monday.

But over the next 15 auctions, to the end of the compliance period in 2020, the market can probably expect "a reasonable amount of volatility and unpredictability," said Environment Minister Glen Murray.