Canada will provide $2.65 billion over five years to help developing countries deal with climate change, Prime Minister Justin Trudeau announced Friday at the Commonwealth summit in Malta.

The announcement comes ahead of the United Nations’ climate change summit in Paris, which begins Monday.

"Canada is back and ready to play its part in combating climate change and this includes helping the poorest and most vulnerable countries in the world adapt," Trudeau said in a statement.

The $2.65-billion announcement is part of Canada’s pledge to contribute to an international climate fund that aims to raise US$100 billion every year by 2020.

Speaking to CTV’s Power Play, Liberal MP Peter Schiefke described the investment as a pre-emptive measure before climate change gets worse in developing nations, which will inevitably turn to the West for aid.

“The reality is that climate change is going to affect those most vulnerable, particularly those living in developing nations, far greater than it is going to affect us here in Canada, the United States and Europe,” Schiefke said.

“We would rather invest now … than to basically be on the hook for tens of billions of dollars 20, 30 years down the road when these countries are calling on Western countries.”

Conservative environment critic Ed Fast described the investment as “irresponsible” and said his party is “asking a lot of questions” about the funds.

“Questions such as who’s paying for this $2.65 billion that is going to be spent outside of Canada? I think we all know the answer to that. It’s taxpayers,” Fast said.

Instead, he insisted that “those funds could be better invested here in Canada.”

Schiefke shot back by targeting Stephen Harper’s environmental legacy, saying that “not taking any action on climate change for 10 years was irresponsible.”

But NDP environment critic Nathan Cullen said it’s been more than 10 years since Canada’s environmental policy has been off track.

“It’s been since these talks began 21 years ago. Canada first showed up (and) eventually signed on to some ambitious targets under the Chretien Liberal government (and) failed dramatically to reach those,” Cullen said.

Reiterating comments made earlier Friday by NDP Leader Tom Mulcair, Cullen called on Trudeau to outline a detailed plan for climate change ahead of the Paris talks.

“Canada’s influence will be somewhat muted if Canada is unable to tell the world what our commitment is going to be,” he said. “When will Canada have a goal to show the world?”

The $2.65-billion announcement was quickly welcomed by World Vision Canada, which described the investment as “a good first step.”

“We are eager to work with the government to see that Canada focusses its efforts on supporting people individuals and communities, especially children, who are the most vulnerable to the hardships of climate change,” said Jennifer Slawich, senior policy advisor for World Vision Canada, in a statement.

Climate change is at the top of the agenda as Trudeau joins leaders of Commonwealth countries in Malta for a three-day summit.

Foreign Minister Stephane Dion has called the meeting a “training camp” for the United Nations’ climate change conference, which begins next week in Paris. But the heads of 53 nations formerly under British rule will also be discussing terrorism, national security and the ongoing refugee crisis, CTV’s Ottawa Bureau Chief Robert Fife reported Friday.

Fife said that Trudeau was expressly asked to attend the biennial meeting of the Commonwealth leaders by U.S. President Barack Obama and German Chancellor Angela Merkel, who wanted him to stress the importance of a climate change agreement at the end of talks in Paris.

Dion has said that he expects the negotiations at the COP21 conference in Paris to be “intense,” but he believes they will end with a “robust agreement” on how to tackle the effects of climate change around the world.

Queen Elizabeth II opened the summit in Valletta Friday by praising the accomplishments of the Commonwealth nations.

"Prince Philip and I first came to live here in Malta in 1949, the year the Commonwealth was founded," she said. "I have been privileged to witness this transformation and to consider its purpose."

French President Francois Hollande is also expected to address the Commonwealth leaders on Friday. He’s the first French head of state to make a speech at the Commonwealth summit.

With files from The Canadian Press