BBC: US scientists say that 2012 was the among the 10 warmest the world has experienced since 1880.
Researchers from Nasa said it was the ninth warmest year while experts from another American agency said it was the tenth.
Both teams said that temperatures would have been higher if it hadn't been for the the La Nina weather pattern that brought cooling to some regions.
The scientists were equally certain that carbon dioxide was the principal driver of the rise over the past 50 years.
The National...