Mongabay: While nations around the world have committed to keeping temperatures from rising 2 degrees Celsius (3.6 degrees Fahrenheit) above the pre-industrial era, new research published in Science suggests that the global climate could hit a tipping point at just 1.5 degrees Celsius (2.5 degrees Fahrenheit). Studying cave stalactites and stalagmites in Siberia, scientists found that at about 1.5 degrees Celsius the Siberian permafrost melts, potentially releasing a greenhouse gas bomb of 1,000 giga-tonnes,...