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Ground Based Observations


Notes:

There are many sources of ground based observations. Some are indicative of local short term changes and others measure changes in long term averages. Temperature measurements near cities have been biased by heat island effects and are invalid for use to detect trends in global averages. Ground based temperature measurements cover only a small fraction of the Earth's surface which also makes them inadequate for determining trends.

Ground based temperature measurements are useful only for correlating satellite measurements made over small regions of the surface.

It's also meaningless to compare changes in long term averages to instantaneous changes. This is a common mistake made in many arguments.