Guardian: * Scientists are more certain than ever that humanity is to blame for rising temperatures. The head of the United Nations' World Meteorological Organisation, Michel Jarraud, said "it is extremely likely that changes in our climate system in the past half century are due to human influence." The report says: "Human influence on the climate system is clear. This is evident from the increasing greenhouse gas concentrations in the atmosphere, positive radiative forcing, observed warming, and understanding...