An anonymous reader writes: A panel of expert climate scientists appointed by the United Nations has come to a consensus on an upper limit for greenhouse gases. The panel says we will blow past this limit in just a few decades if emissions continue at their current pace. 'To stand the best chance of keeping the planetary warming below an internationally agreed target of 3.6 degrees Fahrenheit above preindustrial levels and thus avoiding the most dangerous effects of climate change, the panel found, only about 1 trillion tons of carbon can be burned and the resulting gas spewed into the atmosphere. Just over half that amount has already been emitted since the beginning of the Industrial Revolution, and at current rates of energy consumption, the trillionth ton will be released around 2040, according to calculations by Myles R. Allen, a scientist at the University of Oxford and one of the authors of the new report. More than 3 trillion tons of carbon are still left in the ground as fossil fuels.' You can read a summary of the report's findings online (PDF). It says plainly, 'It is extremely likely that human influence has been the dominant cause of the observed warming (PDF) since the mid-20th century.'