And let's not overlook the bottom line. Global climate fluctuates naturally, so simply claiming a warm year isn't enough. That's not the profile of NOAA's warming. The increasing trend of temperatures that we see, we believe, is at least partially attributed to human activities. The odds that we would be wrong, that there is no relation to human activity, is in the area of 5 to 10 percent.
Human activities do affect climate.
Farm irrigation increases humidity, which could affect climate and temperature around ground stations. Diverting rivers for irrigation raises ocean salinity and can affect ocean circulation and weather patterns. Commercial airline traffic, spreading ice particles from contrails, may create a regionally enhanced greenhouse effect. In short, for all the heavy breathing on the part of reporters, particularly television reporters with the main networks, Karl's statements were rather non-alarmist. Even the statements by NOAA Associate Administrator Joe Friday were less than hair-raising, compared to what we often see in print.