As tens of thousands of participants prepare to descend on Paris for a global climate change conference, Canada's foreign affairs minister says he doesn't think they are likely to achieve their goal.

The United Nations Paris Climate Conference aims to get countries to set emissions reductions targets that would keep global temperatures from rising more than 2 C above pre-industrial times.

While Foreign Affairs Minister Sté​phane Dion says the work at the Paris conference is important, he doesn't expect that goal will be achieved.

"If you compare with what the science is asking us to do, it's very unlikely that Paris will deliver a 2 C agreement," Dion told reporters at the APEC summit in Manila on Wednesday.

Dion is accompanying Prime Minister Justin Trudeau on his new government's first foray onto the international scene.

From the G20 to meetings with Obama and the Queen, and capping it off with the climate change conference in Paris, the PM has a packed schedule in November. 0:29

A series of various international meetings are taking place this month, and while not directly related, will culminate in the Paris conference — at which some 185 countries are expected to be represented.

As Canada's then environment minister, Dion chaired the COP11 UN climate conference in Montreal 10 years ago this month.

Dion chaired COP11

At the time, the deal extended the Kyoto Protocol for those who had ratified it, but what was hailed as a larger victory was the agreement from some of the world's largest emitters of greenhouse gasses — who remained outside Kyoto — to join talks aimed at reducing their emissions nonetheless.

The United States has since set reduction targets for 2025 of about a quarter below 2005 levels. China has agreed to aim to stop increasing its emissions by 2030.

Dion says that isn't enough.

"We know already what the large emitters have committed to do and the assessment of the United Nations is 2.7 [degrees] of warming, instead of two," he said, "But if we have no agreement, we may go to three or four."

Trudeau made fighting climate change a central part of his election campaign and is committed to putting a price on carbon in an effort to bring down Canada's emission levels.

To that end, he will meet with provincial and territorial leaders on Monday in an effort to present a plan in Paris that has the support of all levels of government in this country.

The Paris conference begins a week later, on Nov. 30.

O bama optimistic

Also speaking at APEC in Manila, U.S. President Barack Obama acknowledged there was still a lot of work to do before Paris.

"Nevertheless, I'm optimistic that we can get an outcome that we're all proud of, because we understand what's at stake," Obama said.

Another participant compared climate change to cancer, and Obama agreed.

"You don't want to get to stage four," he said. "We all have a huge investment in making sure our children, our grandchildren are able to enjoy prosperity, and that's dependent on a planet that accommodates us."