The melting of polar ice caps raised sea levels by nearly half an inch (11 millimeters) over the last two decades, scientists said Thursday, calling it the most definitive measure yet of the impact of climate change.

There have been more than 30 previous estimates of whether and how much the ice caps are shrinking. But the numbers were often vague, with wide ranges, and different studies sometimes contradicted each other, the researchers said.

Scientists Thursday announced new evidence that Mercury, the planet orbiting nearest the Sun, hosts massive caches of ice and revealed new information on how water reached our solar system's inner planets.

"The new data indicate the water ice in Mercury's polar regions, if spread over an area the size of Washington DC, would be more than two miles (3.2 kilometers) thick," said David Lawrence, a researcher participating with NASA's mission to study Mercury.

A small humanoid robot that can talk will be sent into space to provide conversational company for a Japanese astronaut on a six-month mission, according to new plans.

The miniature robot will arrive at the International Space Station next summer, a few months ahead of astronaut Koichi Wakata, Japan's Kibo (Hope) Robot Project office said Thursday.

People can be startled at the depth of the Grand Canyon. Now, scientists say dinosaurs may have been, too -- the mighty gouge in the earth is that old.

Scientists have long argued over the age of the multicolored canyon, which is over a mile deep (nearly two kilometers) as many as 18 miles wide (29 kilometers) and 280 miles long (450 kilometers.)

A huge red algal bloom along vast stretches of southeastern Australia's coastline Thursday resulted in beaches being closed and turned swathes of usually pristine ocean milky pink.

The algae, noctiluca scintillans, forced the closure of Sydney's Bondi beach and a number of neighboring inlets earlier this week, and government officials said it had now spread along the fringes of two states.

South Korean space officials suspended a crucial rocket launch Thursday, after a technical problem halted the countdown just 17 minutes before the scheduled blast-off.

"It is impossible to resume the launch sequence today," Deputy Science Minister Cho Yul-Rae told reporters at the Naro Space Center on the south coast.

The preservation of the world's forests "is in China's hands", a top environmental campaign group said Thursday, accusing the biggest wood importer and consumer of fueling the illegal timber trade.

"China's role as the world's biggest timber trader means that further progress against illegal logging depends on the nation taking measures," the London-based Environmental Investigation Agency (EIA) said in a report released in Beijing.

As the first phase of the Kyoto Protocol draws to a close, the world will dissect its record for successes to emulate in the fight against global warming -- and pitfalls to avoid.

If all goes well, Kyoto will eventually be superseded by a new worldwide treaty, whose design is being negotiated at U.N. talks in Doha, Qatar.

Work to build a permanent shelter to secure the exploded reactor at the Chernobyl nuclear power plant in Ukraine reached a key milestone on Tuesday when workers raised the arched section that will cover the destroyed unit.

The explosion at reactor number four at the Chernobyl power plant in the early hours of April 26, 1986 sent radioactive fallout into the atmosphere that spread from the Soviet Union across Europe. It remains the world's worst nuclear accident.

Canada's environment minister unveiled Tuesday new regulations to improve fuel efficiency and halve the greenhouse gas emissions of passenger vehicles and light trucks.

The tougher standards, which must still be approved by parliament, would apply to model years 2017 to 2025 and align Canada's regulatory regime with the United States.