Plot of change in effective solar irradiance due to changes
in cloud cover

Reconstructed annual reflectance anomalies, Δp* (black) with respect to the mean anomaly for the regression calibration period, 1999-2001 (gray band). The large error bars result from the seasonal variability of the Earth's albedo, which can be 15-20%. Also plotted (blue) are the ES-observed annual anomalies for 1999-2003 and 1994-1995. The right-hand vertical scale shows the deficit in global SW forcing relative to 1999-2001. The red solid bar represents the accumulated forcing (in W / m2) attributed to the greenhouse gases concentration increase over the last 100 years, from the International Panel for Climate Change (2001).
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Image credit: Earthshine Project, BBSO.