It All Depends on Where You Stick That Thermometer

According to the most reliable summaries of the earth's surface temperatures for the whole globe, which go back no further than 1861, there was a warming period in the first half of the twentieth century, lasting from about 1910 to 1940. That was followed by a cooling period from 1940 to 1975. Since 1975, we have experienced a slight warming trend. The three periods combined give us a surface temperature increase of perhaps one degree Fahrenheit for the entire twentieth century.

But there is a problem. Satellite measurements of atmospheric temperatures do not agree with these surface readings. Satellite measurements began only in 1979, and they have shown no significant increase for atmospheric temperature in the last century. Balloon readings did show an abrupt, one-time increase in 1976-1977. Since then, however, those temperatures seem to have stabilized.

Environmentalists believe that the twentieth-century warming was caused by human activity, primarily the burning of fossil fuels...

The [Greenhouse] effect itself is not disputed by scientists, but whether man-made carbon-dioxide emissions have been sufficient to cause measurable global temperature increase over the last thirty years is a matter of fierce debate ...

The surface data itself suggests that man-made carbon dioxide has not been sufficient to increase global temperatures. Consider the period 1940-1975, a time of considerable fossil fuel consumption. Coal-fired plants emitted smoke and fumes without any Green party or environmental ministers to restrain them. Yet the Earth cooled slightly. Also, if manmade global warming is real, atmospheric as well as surface temperatures should have steadily increased. This has not happened. Increases were recorded only in the late 1970s, but these were probably caused by a solar anomaly, not by anything man was doing.

The Politically Incorrect Guide to Science

UPDATE:

General global warming thinking would be that the warming of the troposphere (red) results in the stratosphere (blue) being cooler. However, several times on the chart both are warming (like the summer of 1997).