2013 - the world's temperature kept on rising

Global temperatures continued rising in 2013 despite the cold snap that hit parts of the US this winter, NASA research shows. Last year tied with 2009 and 2006, making it the seventh warmest year since record-keeping began back in 1880. The report was released on Tuesday by NASA's Goddard Institute for Space Studies (GISS) in New York. GISS climatologist Gavin Schmidt said such long-­term trends are "unusual".