A study warns that the Earth's temperature is approaching a level not seen in a million years, implying that we are getting close to "dangerous" levels of human pollution. The study finds that, while the world warmed slowly during the century to 1975, it has warmed at a more rapid rate of about 0.2 degrees Celsius (0.36 degrees Fahrenheit) per decade thereafter. The researchers say the global mean temperature is now within one degree Celsius (1.8 degrees Fahrenheit) of the maximum mean temperature of the past million years. Based on a 0.2-degree-Celsius increase per decade, that high point could be...