UN climate talks in Paris tasked with beating back the threat of global warming are scheduled to conclude on Friday.  

This is what brought them together in the first place:

Beijing's first ever red alert for smog expired Thursday, as blue skies and sunshine replaced the thick haze that covered the city for days.

The Chinese capital put its air pollution emergency plan into action earlier this week, pulling half of all private vehicles off the streets from Tuesday, ordering many factories to close and recommending that some schools allow students to remain home.

Karachi, 2050: The sprawling megacity lies crumbling, desiccated by another deadly heatwave, its millions of inhabitants suffering life-threatening water shortages and unable to buy bread that has become too expensive to eat.

It sounds like the stuff of dystopian fiction but it could be the reality Pakistan is facing. With its northern glaciers melting and its population surging -- the country's climate change time bomb is already ticking.

Tears flow often -- blood has once -- as climate negotiators from 195 nations gather every year in a different corner of the world for a physical and emotional endurance race.

Nerves are known to fray as the delegates' high-stakes mission to save humanity clashes head-on with the intransigence that comes from their other mandate to defend narrow national interests.

Ministers in Paris have until Friday to conclude a 195-nation pact to stop Earth's climate becoming inhospitable to humans and other species.

If humankind continues to emit greenhouse gases unabated, the average global temperature by 2100 will be about 5.2 degrees Celsius (9.4 degrees Fahrenheit) higher than pre-Industrial Revolution levels.

French hosts of 195-nation climate rescue talks released a crucial new blueprint Wednesday, reporting important progress but some sticking points two days ahead of the deadline for a U.N. deal.

Foreign Minister Laurent Fabius said the document revealed "emerging compromises" on the way to a historic agreement to rein in heat-trapping greenhouse gas emissions that warm the planet.

Wealthy nations have come under attack from developing countries over proposed financial commitments designed to help them deal with the effects of global warming.

The row, which came at the close of the first week of the crunch Paris climate talks, was over the wording of a proposal in the draft text of a potential agreement released on Friday, which became the subject of long negotiations into the early hours of Saturday morning.

The Himalayan kingdom of Bhutan has made the world’s most far-reaching climate promise to the Paris climate summit, according to new analysis from a respected climate change think tank.

Almost three quarters of the mountainous nation is covered in forests, often watered by snowmelt rivers, and Bhutan has pledged to reforest its land even further. Last summer, it set a world record for the most trees planted in one hour – nearly 50,000.

Honduras, Myanmar and Haiti top a new list of nations hardest hit by two decades of storms, floods, landslides and droughts that killed more than half a million people, climate analysts say.

They warn of more frequent disasters if Earth's overheating cannot be tamed.

The survival of seabirds including puffins and kittiwakes on St Kilda – the island archipelago home to one of the world’s most important seabird populations – is being threatened by climate change, striking new evidence shows.

Naturalists have discovered that the kittiwake, a small migratory gull with ink-black wing tips, is on the brink of disappearing from St Kilda. The remote cluster of Scottish islands in the eastern Atlantic is the UK’s only place with two Unesco world heritage site listings – for its culture and natural history – and one of only 24 sites with a dual listing worldwide.