Paris: World leaders launch a whirlwind day of talks in the French capital on Monday aimed at forging an elusive agreement to stave off calamitous global warming.

The summit kicks off nearly a fortnight of talks intended to end two decades of international bickering with a pact that would limit emissions of the greenhouse gases blamed for climate change.

Negotiators have vowed to forge an ambitious deal to honour the 130 people killed in the 13 November bombing and shooting attacks that shook the French capital.

Minutes after touching down in Paris, US President Barack Obama joined his French counterpart Francois Hollande to lay flowers at the Bataclan concert hall, the site of the worst of the bloodshed.

Scientists warn that unless action is taken soon mankind will endure ever-worsening catastrophic events, such as droughts that will lead to conflict and rising sea levels that will wipe out low-lying island nations.

‘We have to decide how we will be living together on this planet,’ French Foreign Minister Laurent Fabius, who is also the president of the UN-brokered talks, said Sunday as he appealed to negotiators for compromise.

About 150 leaders will be in Paris on Monday for the first day of the talks, having accepted an invitation from the French hosts aimed at injecting much-needed political momentum into the tortuous negotiations.

The United Nations has been hosting annual summits to tackle the vexed global warming issue since 1995, but all previous efforts have foundered, primarily due to deep divisions between rich and poor nations.

Several battle line issues are still yet to be resolved.

Many poor nations insist rich countries bear the most responsibility for tackling the problem, because they have burnt the most fossil fuels since the Industrial Revolution on their way to prosperity.

But the United States and other developed nations insist more must be done by China, India and other emerging countries, which are burning increasing amounts of coal to power their fast-growing economies.

Potential stumbling blocks in Paris range from finance for climate vulnerable and poor countries, to scrutiny of commitments to curb greenhouse gases and even the legal status of the accord.

‘No planet B’

Still, important progress has been made ahead of the meeting. One of the key successes has been a process in which 183 nations have submitted voluntary action plans on how they would tackle global warming.

While not nearly enough, UN climate chief Christiana Figueres said these provide the architecture for more ambitious efforts that could eventually limit global warming to less than two degrees Celsius (3.6 degrees Fahrenheit) from pre-Industrial Revolution levels.

Two degrees C is the threshold at which scientists say the worst impacts of global warming will be inevitable.

The US and France said 20 countries will also pledge on Monday to double their investments in clean energy.

To pressure world leaders into putting aside their differences and forging an agreement, more than half a million people participated in climate protests around the world over the weekend.

‘There is no planet B’ and ‘Our Children Need a Future’ read placards held by some of the 50,000 people who turned out in London’s Hyde Park, in scenes replicated across the world.

‘The charge from the streets for leaders to act on climate has been deafening, with record numbers turning out across the world,’ said Emma Ruby-Sachs, campaign director for Avaaz, one of the organisers.

French authorities had banned protests in Paris due to security fears following the terror attacks claimed by the Islamic State group.

But in a show of defiance against the militants and determination to have their voices heard on climate change, thousands of people in Paris gathered to create a two-kilometre (1.2-mile) human chain.

Their stand was disrupted, however, when a band of anti-capitalist militants infiltrated the protests, leading to clashes with riot police which saw close to 300 people arrested.

Still, the Paris attacks appeared to have galvanised many world leaders in their determination to stand up to terrorism and push on with the climate struggle.

‘It’s an opportunity to stand in solidarity with our oldest ally... and reaffirm our commitment to protect our people and our way of life from terrorist threats,’ Obama said in a Facebook post before leaving Washington.