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The Discovery of Global Warming                      Deacember 2009

Global Mean Sea Level (GMSL) from tide gauges, with an inset showing recent, highly accurate satellite measurements. Shaded areas indicate uncertainty. Sea levels have generally risen since the end of the last Ice Age, more in some places than others. But the best fit to the data (dashed line) shows a noticeable acceleration of the rise since the mid 20th century. That is just what greenhouse effect models predicted would happen because of expansion of sea water under the influence of global warming. A further acceleration of the rise is expected due to melting glaciers and ice sheets, but their contribution is hard to determine or to predict.

graph showing sea level rise 1870-2005

From John A. Church and Neil J. White, "20th Century Acceleration in Global Sea-Level Rise." Geophysical Research Letters 33 (2006): L01602 [doi:10.1029/2005GL024826.]
Copyright © 2006 American Geophysical Union. Reproduced by permission of American Geophysical Union..