claim: Temperatures in the Southwest increased by nearly two degrees Fahrenheit (one degree Celsius) from 1901 to 2010, and some climate models forecast a total rise of six degrees or more by the end of this century.
evidence: During the late 20th century, a scientific consensus evolved that increasing concentrations of greenhouse gases in the atmosphere cause a substantial rise in global temperatures and changes to other parts of the climate system, with consequences for the environment and for human health.