Ottawa Centre MP Catherine McKenna told CBC News that Canada needs to play a "significant role" to tackle global climate change following her appointment as minister of environment and climate change on Wednesday.

McKenna, the only Ottawa-area member of cabinet, walked up to Rideau Hall Wednesday morning front and centre, near Prime Minister Justin Trudeau and his wife, as he led his new ministers to be officially sworn in.

Under the previous Conservative government, Leona Aglukkaq was minister of the environment — with no mention of climate change.

"We believe that climate change is a huge problem that we need to be addressing and so we're certainly highlighting this," McKenna told Adrian Harewood on CBC News at 6.

"This is a really important file to Canadians — both the environment but also tackling climate change and we need to be ambitious and I'm just ready to work really hard and get down to action."

The appointment comes less than a month before the United Nations conference on climate change in Paris that begins November 30. McKenna said Canada will come up with a plan for a "huge reduction in emissions" and will play a "constructive role" with governments.

Ottawa's Minister Catherine McKenna3:09

Earlier in the day, Prime Minister Justin Trudeau said that "Canada is going to be a strong and positive actor on the world stage," including at the conference in Paris.

"That's why we have a very strong minister not only of the environment, but of environment and climate change, who will be at the heart of this discussion." he said.

Less than 4 weeks until UN talks

As a lawyer, McKenna focused on international trade and competition, according to her website. She was also a legal adviser and negotiator for the United Nations peacekeeping mission in East Timor.

Liberal Cabinet Catherine McKenna Ottawa Justin Trudeau

Ottawa Centre MP Catherine McKenna, far left, accompanies Justin Trudeau, right, as he led his cabinet into Rideau Hall to be officially sworn in. (The Canadian Press)

Environmental Defence executive director Tim Gray expressed hope her experience will help her navigate the difficult climate change file in Paris, where countries will try to reach a new agreement to keep global temperatures from rising more than 2 C.

Paris will be McKenna's first test, Gray said in a statement.

"It's a crucial moment for Canada to arrive with a clear plan that will contribute meaningfully to forging a solution to this critical global issue."

McKenna 'breath of fresh air'

On the local front, Ottawa's Mayor Jim Watson said he has a good working relationship with McKenna, as well as other cabinet ministers in portfolios of interest to the city: Marc Garneau in Transportation and Scott Brison in Treasury Board.

It's not yet clear which minister will assume responsibility for the National Capital Commission.

With a slimmed down cabinet, Watson was not surprised McKenna was the only Liberal MP from the region to take an oath at Rideau Hall. He noted the region had only one cabinet minister from Ottawa and Gatineau, Pierre Poilievre, when Parliament was dissolved in August.

McKenna beat Paul Dewar, the longtime former NDP MP in Ottawa Centre, after a campaign that began long before the election was called.

"I've found her to be a breath of fresh air when dealing with a lot of issues that are important to us locally, whether it's the victims of communism monument or the use of U.S. embassy or reform of the NCC," Watson said of McKenna. "She was certainly aggressive in her campaign and this is a good fit for her."