Earth's average near-surface atmospheric temperature rose 0.6 \u00b1 0.2 \u00b0 Celsius (1.1 \u00b1 0.4 \u00b0 Fahrenheit ) in the 20th century [1] . The current scientific consensus is that "most of the observed warming over the last 50 years is likely to have been attributable to human activities " [2] . The