Air pollution in Iran's capital hit its worst level -- for a day without a sandstorm -- in at least nine months on Monday, prompting warnings that all citizens should stay indoors.

"Tehran's air is unhealthy for all," said the city's transport and traffic department on a municipality-owned website.

Pope Francis on Sunday hailed the U.N. climate accord reached in Paris but warned the key now lay in its implementation, especially in help for the poor.

"The climate conference has just ended in Paris with an agreement that many describe as historic," the pontiff said at Angelus prayers in St. Peter's Square.

In the future, China will shut down a factory before it even pollutes -- or so it hopes, as it deploys big data in the fight against bad air.

In Beijing's environmental bureau, a team of engineers tend to giant mainframe computers that keep a watchful eye on the city's pollution.

A former global champion of renewable energy, Spain wants to make up the ground it lost during the economic crisis when it reversed its policy slashing subsidies and decimating the sector.

With roughly 300 days of sunshine per year and regions that receive strong winds, Spain was a world leader in 2007-08 in solar and wind power production, helped by generous state subsidies.

On the edge of the Sahara desert, engineers make final checks to a sea of metal mirrors turned towards the sun, preparing for the launch of Morocco's first solar power plant.

The ambitious project is part of the North African country's goal of boosting its clean energy output with what it says will eventually be the world's largest solar power production facility.

French hosts of U.N. talks submitted to cheers and applause Saturday a proposed 195-nation accord to defeat global warming, which threatens mankind but needs an energy revolution to resolve.

Foreign Minister Laurent Fabius, on the brink of tears after presiding over nearly a fortnight of talks in Paris, delivered the proposal to ministers who must now decide whether to approve it, possibly within hours. 

U.S. President Barack Obama and his Chinese counterpart Xi Jinping are committed to reaching an "ambitious" climate deal in Paris, the White House said Friday, after a late night phone call between the two leaders.

"Following his productive calls earlier this week with Prime Minister (Narendra) Modi and Presidents (Francois) Hollande and (Dilma) Rousseff, President Obama spoke by phone last night with President Xi Jinping of China to coordinate efforts at the ongoing Paris climate conference," a White House statement said.

U.N. Secretary General Ban Ki-moon called Friday on envoys from around the world to take a "final decision for humanity" as they battled to seal a 195-nation climate-saving pact in Paris.

"This negotiation is most complicated, most difficult, but most important for humanity. We have just very limited hours remaining," Ban told reporters as ministers grappled with stubborn differences over pivotal issues.

Sleep-starved envoys tasked with staving off catastrophic climate change are on track to seal a historic accord, the French hosts of UN talks said Friday although the biggest pitfalls were yet to be cleared.

The 195-nation conference in Paris had been scheduled to wrap up on Friday, but was extended another day after ministers failed to bridge deep divides during a second consecutive all-night round of negotiations.

Australia should introduce a “post-disaster humanitarian visa” for Pacific islanders displaced by natural disasters and climate change, a new report from the Migration Council Australia has recommended.

And to boost historically low rates of migration from the Pacific, Australia should consider instituting a green card-style lottery for Pacific islanders to live and work in Australia, and boost seasonal worker numbers to industries such as horticulture.