text: Global warming is a warming trend that has been noticed since about 1860, while the greenhouse effect is a hypothesis that some scientists believe explains why this is happening (they say increased carbon dioxide levels have increased temperatures). \n\nHowever, from 1940-1960 temperatures actually decreased even though this was a time of heavy industrialization (Europe was rebuilding and the U.S. was in a rapid economic expansion). Also, NASA's satellite data (which is considered more accurate and measures the atmospheric temperature but has only been calculated since 1979), actually shows the earth cooling since 1993, in complete disagreement with ground tempertures. IMO, while it is completely possible that the greenhouse effect is why ground temperatures continue to rise, there is simply not enough information yet to support that conclusion.