A space rock popularly dubbed the "doomsday asteroid" because of fears it could smash into Earth a couple of decades from now poses no risk, NASA said after new observations of the object.

Asteroid 99942 Apophis was scanned by optical telescopes and deep-space radars as it made a flyby this week, the National Aeronautics and Space Administration (NASA) said in a press release.

Firefighters were battling scores of wildfires raging in Australia Saturday, as a government commission warned that climate change had raised the risk of scorching heatwaves becoming more frequent.

In the eastern state of New South Wales, some 1,000 firefighters were attempting to douse about 94 wildfires, about dozen uncontained, while fires were also burning in neighboring Victoria and Queensland states.

A government report warned Friday that the United States could face more frequent severe weather including heat waves and storms for decades to come as temperatures rise far beyond levels being planned for.

The draft Third National Climate Assessment, a scientific study legally mandated to advise U.S. policymakers, made few bones that carbon emissions have been causing climate change -- a source of controversy among some lawmakers.

About a dozen killer whales trapped under sea ice appeared to be free after the ice shifted, village officials in Canada's remote north said Thursday, while residents who feared they would get stuck elsewhere hired a plane to track them down.

The whales' predicament in the frigid waters of Hudson Bay made international headlines, and locals had been planning a rescue operation with chainsaws and drills before the mammals slipped away.

Hong Kong's name may mean "fragrant harbour", but cargo ships burning dirty fuel in what is one of the world's busiest ports add to a foul layer of pollution that kills more than 3,000 people a year.

Now the government is vowing to get tough, with activists hoping mandatory restrictions on shipping emissions will be among a raft of measures announced next week aimed at making the city more environmentally friendly.

Western Australians were bracing Friday for a cyclone with residents warned to batten down for storms and destructive winds gusting up to 140 kilometers per hour (90 mph).

Cyclone Narelle was estimated to be 525 kilometers (325 miles) north of Exmouth and 505 kilometers north-west of Karratha near the Pilbara mining region and moving southwest at 13 kilometers per hour.

The U.N.'s climate science panel bemoaned Wednesday a fresh leak of data from a landmark report on global warming that it will start releasing this year.

"Clearly, it is regrettable, all the leaked material is in draft form, internal working documents," Jean-Pascal van Ypersele, vice president of the Intergovernmental Panel on Climate Change (IPCC), told Agence France Presse.

Astronauts chosen for a manned mission to Mars could be in serious trouble if their sleep patterns are disrupted on the lengthy journey, a 520 day simulation has found.

"The success of human interplanetary spaceflight, which is anticipated to be in this century, will depend on the ability of astronauts to remain confined and isolated from Earth much longer than previous missions or simulations," said David Dinges of the University of Pennsylvania, who co-authored the sleep study.

Breeding season is underway for the endangered tortoises of Ecuador's Galapagos Islands, whose mating and nesting habits are carefully watched by wildlife specialists hoping to save them from extinction.

Nesting began last month at Galapagos National Park and will be monitored through June to determine how many female tortoises have prepared nests and how many hatchlings are likely to emerge.

Japan will launch a survey of its Pacific seabed, an official said Thursday, hoping to find rare earth deposits large enough to supply its high-tech industries and reduce its dependence on China.

Researchers from the Japan Agency for Marine-Earth Science and Technology will start the probe from January 21 on the seabed near Minamitorishima island, some 2,000 kilometers (1,250 miles) southeast of Tokyo, he said.