The rationale for changing behavior given climate change is threefold.  Since 1885 the average temperature has gone up almost 1 degrees and will continue to rise.  According to U.K. scientests.  There is a 95% confidence interval that human activity is causing climate change or at least half of it.  Futhermore these same scientists have also concluded that the earth can only handle 1 trillion tons of carbon.  So far humans have burned 500 billion tons which caused the temperature to rise 1 degrees celcius.  This leaves another 500 billion to burn and given the rate of consumption it will only last for 30 years by which the temperature will rise another 1 degrees celcius.  Attached is a chart showing the relationship between temperature in the last 8 years and the decline in rainfall over the same period.