Nova Scotia's environment minister walked out early from a national meeting on carbon pricing Monday, hours after Prime Minister Justin Trudeau issued an ultimatum to provinces to adopt carbon pricing, or have it imposed, by 2018.

"We're struggling to understand where the PM's message came from today and what 's going to happen moving forward," provincial Environment Minister Margaret Miller said in Montreal.

Miller and colleagues from Saskatchewan and Newfoundland and Labrador left a meeting with provincial ministers and their federal counterpart, Catherine McKenna, before a planned photo opportunity and news conference.

"This is just about going home and talking to our premier and seeing what our next steps are," Miller said as she walked away.

Nova Scotia high energy rates

The McNeil government has repeatedly held out hope Nova Scotia would be spared carbon pricing because the province has adopted expensive renewable energy like wind power, which is embedded in electricity rates. Rates have risen by 62 per cent since 2005.

"We want to help meet the federal government's national target, but we need a solution that recognizes our results, and one that won't punish the pocketbooks of Nova Scotians, who are already paying among the highest energy rates in the country," Miller said.

The argument has not persuaded Ottawa, which has given Nova Scotia until 2018 to adopt a cap-and-trade system or an outright tax.

The federal government says the province has taken no steps to address carbon pricing on liquid fuels like gasoline and home heating oil.

Carbon pollution price

On Monday, Trudeau said the proposed price on carbon pollution should start at a minimum of $10 per tonne of greenhouse gas in 2018, rising by $10 each year to $50 per tonne by 2022.

Dalhousie University energy security expert Larry Hughes has broken down the impact of a $30 per tonne carbon tax in Nova Scotia. Thirty dollars per tonne is the tax in place in British Columbia.

In an analysis provided to CBC News, Hughes said a B.C. tax would add nearly seven cents per litre to the price of gasoline, increase electricity bills by 1.8 cents per kilowatt hour and add nearly nine cents a litre to the cost of home heating oil.

Treasury Board President Scott Brison, who is MP for the Nova Scotia riding of Kings-Hants, said the federal government has "built-in flexibility to accommodate for the efforts that provincial governments have already undertaken."

"Nova Scotia took a regulatory approach to cut GHG emissions in its electricity system," he said.‎ "There may be an opportunity to take that into account in a carbon pricing model designed by the Nova Scotia Government."