[[Global warming]] has occurred; air temperature has risen one degree Fahrenheit since the end of the Little Ice Age in the late nineteenth century. What [[environmentalist]]s and real [[scientist]]s disagree on is the cause. | [[Global warming]] has occurred; air temperature has risen one degree Fahrenheit since the end of the Little Ice Age in the late nineteenth century. What [[environmentalist]]s and real [[scientist]]s disagree on is the cause. |