Climate change is likely to cut Antarctica's 600,000-strong emperor penguin population by at least a fifth by 2100, a study suggests.

A new technique known as "supercooling" can preserve organs for days before they are transplanted, US researchers claim.

Women should not worry about using sperm from older donors as the success rate is the same as for younger men, doctors say.

The US space agency is set to put a high-resolution carbon dioxide observatory into orbit - a re-build of a satellite destroyed on launch five years ago.