This is very iffy stuff. The data from weather balloons, some experts believe, indicate that global temperatures have actually gotten a little cooler. Temperatures have been collected in cities for a long time, but this can be very deceptive because cities are generally warmer than the surrounding countryside and cities have been growing in size over time, with concrete structures and paved streets replacing wooden structures and dirt paths. In short, places and structures that hold heat are glowing. Weather balloons that circle the Earth give a much more balanced picture of what is happening to temperatures on the planet as a whole.
Some experts say that global temperatures have actually gotten a little cooler, in fact.
Global data show the Earth's temperature the same in 1990 as in 1980. However, the temperature went up and down in between. Pick a low point on these oscillations, and the temperature has been rising since then. Pick a high point, and the temperature has been falling. Yet we are expected to pile staggering costs onto the American consumers and taxpayers because of speculative theories turned into computer models.