Premiers Kathleen Wynne and Philippe Couillard agreed to build "a stronger and more competitive low-carbon economy" to fight climate change, but wouldn't say when people could start paying a carbon tax.
Couillard says he sees opportunities to grow the economy as new technologies are developed to reduce greenhouse gases.
And he says there are enormous costs from not dealing with climate change such as coastal erosion and storm damages that are eventually passed on to taxpayers.
The premiers also signed agreements to help each other with electricity, with Ontario making 500 megawatts available to Quebec in the winter and Quebec returning the favour in the summer months when Ontario's demand is greater.
Wynne and Couillard also agreed projects like the Energy East pipeline should proceed only when they are environmentally sustainable and have local support.
The proposed Energy East pipeline would carry oilsands crude to refineries on the east coast for export overseas.
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