World leaders delivered a range of messages, from optimist promises to dire warnings, as talks began Monday near Paris on reducing man-made emissions behind climate change.

Representatives from more than 150 nations are attending 12 days of negotiations aimed at completing a binding framework for post-2020 emissions reductions.

Canada is one of 20 countries planning to double research and development over the next five years on clean energy technology, Prime Minister Justin Trudeau told the summit.

Prime Minister Justin Trudeau told reporters at the COP21 in Paris that several provinces in Canada have already made 'serious' commitments to fight climate change. (CBC)

Trudeau joined French President François Hollande, U.S. President Barack Obama and Microsoft co-founder Bill Gates in announcing the launch of the clean technology initiative called Mission Innovation at the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change (COP21).

In a statement, the Prime Minister's Office said Canada has a plan to invest an additional $100 million each year in clean technology producers. It said the government will also invest an additional $200 million each year to support innovation and the use of clean technologies in the natural resources sector.

Climate change an opportunity for Canada

Trudeau said Canada will also help poorer nations cope with global warming. Last week, his government promised to spend $2.65 billion over five years to help developing countries reduce their emissions and adapt to climate change.

"We will help the developing world tackle the challenges of climate change," Trudeau said. "Many of the world's most vulnerable countries have done little to contribute to the problem, but face the most significant consequences."

Trudeau called climate change a "historic opportunity" for Canada to develop an economy that relies on green infrastructure, which he said would create economic growth.

He earlier told reporters that in the coming 90 days — before the next first ministers' meeting — his government will have a "lot more work to do" on reducing emissions.

He said the Paris summit highlights the challenges of climate change but also offers an opportunity for Canada to be the "purveyor of solutions" and "forward, innovative thinking."

"We have a tremendous level of action and commitments made, and we know we have work to do, which is why we started the work of getting together even before coming to Paris," he said at the briefing, where he appeared alongside the premiers of Alberta, B.C., Ontario, Quebec and Saskatchewan.

'Fight of our generation'

"We must rise to this moment," Obama said in his opening remarks.

U.S. president's speech to the Paris climate change conference 12:53

"The growing threat of climate change could define the contours of this century more dramatically than any other," he said. "Fourteen of the 15 warmest years on record have occurred since the year 2000, and 2015 is on pace to be the warmest year of all."

King Abdullah, of Jordan, delivered one of the most urgent appeals for action, speaking for the second-most water-poor country on Earth, which imports more than 90 per cent of its energy while struggling to host 1.4 million Syrian refugees.

"This is the fight of our generation ... the entire planet is in danger," he said. "We must act collectively, with foresight, responsibility and determination."

Mongolian President Tsakhiagiin Elbegdorj told world leaders there should be "no more disappointments" and he stressed the importance of each country tracking its emissions.

"[An agreement] must contain heightened accountability for the commitments we make. We cannot afford one more global document if there is no accountability," he said.

German Chancellor Angela Merkel said fighting global warming is common sense for the world's economy. (Stephane Mahe/Reuters)

German Chancellor Angela Merkel said fighting global warming shows a humane spirit, but also makes economic common sense. "Billions of people are pinning their hopes on what we do in Paris."

Obama met with Indian Prime Minister Narenda Modi during the opening day of the summit. The U.S. president said India must curb its carbon dioxide pollution even while it works to eradicate poverty, prioritize growth and promote economic development.

He also said he and Modi agreed that climate change is an "urgent threat," one that calls for deeper co-operation between their countries. Modi said India's responsibilities on climate change "will be fully undertaken and fulfilled."

U.S. President Barack Obama, right, meets with Indian Prime Minister Narendra Modi at the climate change summit. (Kevin Lamarque/Reuters)

Western countries have said that at this round of talks, all countries must chip in, including China, the world's biggest emitter of greenhouse gases, followed by the U.S. and India.

China emits about 30 per cent of the world's greenhouse gases and the U.S. about 16 per cent.

The biggest issue facing the 151 heads of state and government at the summit is who should bear most of the burden of closing that gap: wealthy Western nations that have polluted the most historically, or developing countries like China and India that are now the biggest and third-biggest emitters of greenhouse gases?

French President François Hollande greets Chinese President Xi Jinping, left, upon his arrival for a working dinner Friday at the Elysée presidential palace in Paris. (Stephane de Sakutin/AFP/Getty Images)

"Addressing climate change should not deny the legitimate needs of developing countries to reduce poverty and improve living standards," Chinese leader Xi Jinping told the conference.

As world leaders and climate negotiators from around the world gather, many are using words like fair, binding, comprehensive and ambitious to describe the agreement they wish to reach.

Russian President Vladimir Putin also addressed the summit, saying his country is ready to cut its greenhouse gas emissions by almost a third over the next 15 years compared with 1990 levels — although the fall in Russia's economy since 1990 means that it could still increase its current emissions.

Putin said Russia will aim to bring its greenhouse gas emissions to 70 per cent of its 1990 level by 2030.​

Russian President Vladimir Putin told the summit that a future global climate deal must include commitments on reducing emissions from both developing and developed countries. (Stephane Mahe/Reuters)

'Script for a new future'

UN Secretary General Ban Ki-moon and Hollande greeted heads of state and government from around the world as they arrived at the conference at the Le Bourget airfield.

Peruvian Environment Minister Manuel Pulgar Vidal, who played host to the last UN climate conference in Lima, said a deal would show the world that countries can work together to fight global warming as well as terrorism.

"We are here today to write the script for a new future," Ban said.

The conference is being held under heavy security after the Nov. 13 attacks in Paris. Most leaders speaking on Monday offered condolences to the victims and praised France for holding the climate talks.

Obama described the COP21 as "an act of defiance that proves nothing will deter us from building the future that we want for our childlren."