'Unprecedented' extremes of weather
3 July 2013 Last updated at 19:51 BST
The first 10 years of the 21st Century were the world's hottest since records began and included unprecedented extremes, according to the World Meteorological Organization.
A report from the organisation says more national temperature records were reported broken between 2001 and 2010 than in previous decades.
David Shukman reports from Death Valley.