Nearly 200 nations adopted the first global pact to fight climate change on Saturday, calling on the world to collectively cut and then eliminate greenhouse gas pollution but imposing no sanctions on countries that don't.

Loud applause erupted in the conference hall outside Paris after French Foreign Minister Laurent Fabius gavelled the agreement Saturday. Some delegates started crying. Others embraced.

The countries had been negotiating the pact for four years after earlier attempts to reach such a deal failed.

This accord marks the first time all countries are expected to pitch in — the previous emissions treaty, the 1997 Kyoto Protocol, only included rich countries.​ Canada signed on to Kyoto, but later backed out in 2011.

'Canadians can be proud'

Prime Minister Justin Trudeau released a statement calling the agreement "historic, ambitious and balanced."

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From left to right, UN climate chief Christiana Figueres, UN Secretary General Ban Ki-Moon, French Foreign Affairs Minister Laurent Fabius and French President François Hollande react during the final plenary session at the World Climate Change Conference 2015. (Stephane Mahe/Reuters)

"Canadians can be proud of the strong and positive role we played during these very important international negotiations to address one of the biggest challenges of our generation," he said. "There is much tough work that still needs to be accomplished both at home and around the world to implement the agreement."

He promised to meet with the premiers within the next 90 days.

"We will move towards a climate resilient economy, and we will invest in public transit, green infrastructure and clean technologies to create new jobs and support our communities," he said. "Internationally, we will provide significant support to help developing countries reduce their emissions and deal with the impacts of climate change." 

'For our children'

U.S. President Barack Obama hailed the accord reached as strong and historic, calling it the best chance to save the planet from the effects of global climate change.
 
"Today the American people can be proud because this historic agreement is a tribute to American leadership. Over the past seven years, we've transformed the United States into the global leader in fighting climate change," Obama said.
 
He said the accord shows what is possible when the world stands as one, adding: "This agreement represents the best chance we have to save the one planet that we've got." 

Shortly after the deal was adopted, Canadian Environment Minister Catherine McKenna tweeted: "History is made. For our children."

UN Secretary General Ban Ki-moon called it "a monumental triumph for people and planet."

"History will remember this day," he said. 

U.S. Secretary of State John Kerry said the pact will "prevent the worst most devastating consequences of climate change from ever happening."

"It's a victory for all of the planet and for future generations," he said. 

Brazilian Environment Minister Izabella Teixeira added: "Today, we've proven that it's possible for every country to come together, hand in hand, to do its part to fight climate change."

The agreement, South African Environment Minister Edna Molewa said, "can map a turning point to a better and safer world."

The deal now needs to be ratified by individual governments — at least 55 countries representing at least 55 per cent of global emissions — before taking effect in 2020.

Under the deal, countries will have to publish greenhouse gas reduction targets and revise them upward every five years, while striving to drive down their carbon output "as soon as possible."

The final text of the agreement commits countries to keeping global warming "to well below 2 degrees C" and hopes to limit it to 1.5 C, with the goal of a carbon-neutral world sometime after 2050. 

In introducing the draft text earlier on Saturday, Fabius, flanked by French President François Hollande and Ban, called the pact "a historic turning point" and said it contained some key provisions. 

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French Foreign Minister and president of the COP21 Laurent Fabius uses to hammer to mark the adoption of the global climate agreement during the final conference at the COP21, the United Nations conference on climate change, in Le Bourget, France. (Francois Mori/Associated Press)

Those include terms making the accord legally binding, as well as the 1.5 C goal — below the 2 C standard scientists say is essential to limiting potentially catastrophic climate change.

That was a key demand of developing countries ravaged by the effects of climate change and rising sea levels.

Another major debate has been over a promise that developed countries should provide $100 billion annually to help poorer states deal with the consequences of climate change. The text sets that figure as a floor by 2020.

Elizabeth May, leader of Canada's Green Party, said the deal is ambitious but balanced, and she's proud of Canada's involvement in the negotiations. 

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"We are not nearly where we need to be yet, but this is a very good moment for the world and Canada played a real role in getting us here," she told CBC News from Paris.

The Green Party later tweeted its congratulations to May, McKenna and Trudeau. 

Not far enough, critics say 

Not everyone is happy with the deal, however.

NDP Leader Tom Mulcair and World Wildlife Fund Canada say merely approving the agreement isn't enough and that the Canadian government must act to reduce fossil fuel emissions.

Canada should have already set "ambitious" federal emissions targets, said an NDP statement, which also called for Canada to move toward a low-carbon economy to develop new, cleaner technology.

Conservative environment critic Ed Fast said the climate deal means little without official emissions targets from the federal government.

He said the government should consult the country's "major emitters" before agreeing to targets.

Fast also expressed concern about job losses in the energy sector. He says tens of thousands of jobs have already been lost, and the new agreement sets the stage for even more cuts.

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United Nations climate chief Christiana Figueres, right, hugs France's Laurence Tubiana, special representative for the COP21, after nearly 200 countries adopted a historical global agreement on Saturday. (Francois Mori/Associated Press)

Paul Oquist, Nicaragua's U.S.-born climate envoy, told climate negotiators that his country is "not able to support the consensus."

He said the agreement does not go far enough and leads to twice as much global warming as the stated goals. His country is one of 10 nations that didn't submit plans to reduce emissions.

Oquist asked for a compensation fund that would pay poorer countries for damages caused by global warming and complained the accord as approved would not let victims sue for compensation.

Thousands of protesters in Paris, under the close watch of riot police, held hands beneath the Eiffel Tower and denounced the pact as too weak to save the planet.

Danielle Lefait, a retired deaf student teacher, said she was protesting because she is afraid of the environmental risks of proposed shale gas extraction in her town of Arras in northern France. Other protesters were angry the accord didn't do more to force governments to give up fossil fuels blamed for warming the planet.

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The slogan 'NO PLAN B' is projected on the Eiffel Tower at the COP21 conference near Paris. Thousands of activists gathered under the tower Saturday to urge further action to limit global warming. (Francois Mori/The Associated Press)

The pact doesn't have any mechanism to punish countries that don't or can't contribute toward its emissions-reduction goals.

The Pembina Institute, a Canadian environmental think-tank, said Canada will only be able to meet the emissions targets under the new Paris Agreement if it brings in a national minimum standard for carbon pricing.

With files from CBC's Kyle Bakx, The Associated Press, The Canadian Press and Reuters