On the heels of our podcast with Stan Goosby, this release from NASA:

A study published July 21 in Science and led by Susan Solomon, of the National Oceanographic and Atmospheric Administration (NOAA), presents new evidence that particles located in the upper layer of the atmosphere — also called the stratosphere — have played a significant role in cooling the climate in the past decade, despite being at persistently low levels.

Check out the story here: http://www.nasa.gov/topics/earth/features/stratospheric-aerosols.html