A hundred prominent artists, academics and public figures signed a combative climate change manifesto released Thursday calling for an end to "climate crimes" and the era of fossil fuels.

Desmond Tutu, Noam Chomsky, Vivienne Westwood and a raft of lesser-known luminaries summoned a grassroots movement to force radical change in the global economy, comparing the cause to the fights against slavery, colonialism and apartheid.

Mandatory water-saving measures in place to fight California's historic drought have produced a sizeable drop in consumption over the past two months, regulators said Thursday.

The measures have been far reaching and the U.S. state's 38 million residents are only allowed to water their lawns on specific days and have been asked to use water-saving hoses, even though it is the height of another punishing summer.

U.N. Secretary General Ban Ki-moon said Wednesday that countries must "accelerate the rhythm of negotiations" on capping global warming ahead of an international climate conference in Paris in December.

"We don't have much time. There remain less than 100 days before the final negotiations," he said, following a meeting with Foreign Minister Laurent Fabius in the French capital.

Sea levels are rising around the world, and the latest satellite data suggests that three feet (one meter) or more is unavoidable in the next 100-200 years, NASA scientists said Wednesday.

Ice sheets in Greenland and Antarctica are melting faster than ever, and oceans are warming and expanding much more rapidly than they have in years past.

In half a century of space travel more than 500 people have glimpsed the Earth from the unique vantage point of the cosmos, yet no black African has been among them.

Now a Nigerian and two South Africans are in a race to become the first after being shortlisted in a global talent search to send a "young icon of the future" into the heavens.

Under attack from hordes of ravenous starfish, Pacific coral is getting help from an unexpected source -- seaweed, an arch enemy, researchers said on Wednesday. 

Seaweed is no friend of the fragile ecosystems of coral reefs, pumping out harmful chemicals, blocking out life-giving sunlight, and rubbing up against and damaging the threatened marine invertebrates.

Deep in the pristine Amazon jungle, Brazil's newest skyscraper has a mission unlike any other: to save the world.

The white and orange metal frame called Amazon Tall Tower Observatory, or ATTO, is a bold new tool in the push to understand climate change and the vital role of rainforests.

Thailand destroyed more than two tonnes of ivory Wednesday -- a victory for animal rights groups fighting against the trade in a country renowned for being a hub for illegal tusks.

The ceremony, in which 2,155 kilograms of raw tusks and carved trinkets were fed into an industrial rock crusher before being incinerated, was presided over by the Thai junta leader Prayut Chan-O-Cha and is the first time the kingdom has taken steps to destroy part of its stockpile. 

Australia's city of Newcastle, which claims to be the world's biggest coal export port, said Wednesday it will pull money out of fossil fuel industries and invest in more sustainable enterprises.

Newcastle City Council, which manages a Aus$268 million (U.S.$191 million) investment fund for Australia's seventh largest city, voted late Tuesday to move progressively towards "environmentally and socially responsible investments".

U.S. President Barack Obama made a full-throated defense of renewable energy Monday, hitting coal-championing critics as free market hypocrites. 

With one eye on a looming battle over power plant emissions limits, Obama took on fossil fuel supporters during a speech in the parched desert oasis of Las Vegas.