ScienceDaily (July 30, 2012) — According to a new Berkeley Earth study released July 29, 2012, the average temperature of Earth's land has risen by 1.5 °C over the past 250 years. The good match between the new temperature record and historical carbon dioxide records suggests that the most straightforward explanation for this warming is human greenhouse gas emissions.
http://www.sciencedaily.com/releases/2012/07/120730142509.htm