Recent research on aerosols in the Earth's atmosphere and global warming suggest, that for the past decade stratospheric aerosols have been are slowing down global warming.

The stratospheric aerosols, which have been released to the atmosphere by either recent volcanic eruptions or human activity, reflect sunlight away from Earth and cools the surface temperatures.

The scientists led by John Daniel of the National Oceanic and Atmospheric Administration's (NOAA) Earth System Research Laboratory analyzed satellite and other data on aerosols, and found that the concentration of aerosols formed from sulfur dioxide have almost doubled in the past decade. According the scientists the aerosols have prevented 0.07 degrees Celsius of warming in average temperatures since 2000.

"Aerosols acted to keep warming from being as big as it would have been," says John Daniel, "It's still warming, it's just not warming as much as it would have been."

The increase in the concentration of stratospheric aerosols could be caused by volcanic activity or human activities such as coal burning. Which source is responsible for the increase in stratospheric aerosols is still being researched.

Source: Scientific American