NYTimes reports three new papers in Science that call attention to a major gap in how the climate system works. The papers report that the Earth is brightening, that is, more sunlight is reaching the earth’s surface and is not being reflected by clouds or volcanic dust or pollution. Scientists don’t exactly know what’s causing the brightening, or how this is affecting the rest of the climate.
The findings of Dr. Wild and his colleagues are based on data through 2001 from a network of ground-based sensors that directly measure the sunlight hitting the ground. But the sensors are not evenly distributed, with the greatest number in Europe, few in Africa and South America, and none covering the 70 percent of Earth’s surface that is water.
Dr. Pinker’s team analyzed satellite data from 1983 to 2001 that covered the globe. Its findings about brightening, which basically agree with Dr. Wild’s, rely on computer models to estimate how much sunlight reaches the surface.
Finally, a team led by Dr. Bruce A. Wielicki of NASA’s Langley Research Center in Virginia reports that measurements from the agency’s Aqua satellite show a slight decrease in the amount of light reflected off Earth since 2000, which corresponds to a brightening on the surface.
So whom does one believe? The models or the sensors or the images? And why isn’t the Earth dimming like the models have predicted? The public likely will view this conflicting data as simply more evidence that climate change is a hoax.