By Mike De Souza

CALGARY, Nov 12 (Reuters) - Canada's oil-rich western Canadian province of Alberta said its recent decision to double its price on carbon emissions was only a first step in its efforts to tackle climate change, Premier Rachel Notley said on Thursday.

Notley said her left-leaning New Democratic government, which ended 44 years of Conservative rule in a May election, would introduce details of its climate change plan "very soon."

Alberta, the largest source of U.S. crude imports, owns the planet's third largest known crude reserves. But its energy-intensive oil sands industry is also frequently a target of environmentalists since it is Canada's fastest growing source of greenhouse gas emissions.

Notley said her climate change plan would introduce an energy efficiency strategy and encourage utility companies to use natural gas and renewable energy to replace coal as a source of electricity. The province would also go beyond its June decision to toughen its carbon pricing regulations so that both Canada and Alberta have stronger policies heading into an upcoming United Nations climate change summit in Paris, she added.

"That was a good start, but more needs to be done," said Notley in a speech in Toronto to the Broadbent Institute, a left-leaning think tank. "So we will do what needs to be done. So that Alberta - and Canada - can stand before the world in December in Paris, and for decades to come, as one of the world's most progressive and environmentally responsible energy producers."

Notley said the failure of previous federal and provincial governments to tackle climate change is harming Canada's economy since its environmental reputation is now affecting the oil industry's ability to get new customers and pipelines, as was the case with the Obama administration's recent decision to reject TransCanada Corp's Keystone XL pipeline.

"Ignoring climate change is a blind alley for both the energy business, and for the province of Alberta," she said.

Newly-elected Canadian Prime Minister Justin Trudeau has also pledged to improve Canada's climate change record and invited Notley and other premiers to the Paris summit. But Trudeau's government has not yet unveiled details, saying that it wants to work with the provinces to find the right solutions.

(Reporting by Mike De Souza; Editing by Andrew Hay)