The recent 'slow-down' of global warming is partly due to an increase of volcanic aerosols into the stratosphere during this century, according to the new research from the Lawrence Livermore National Laboratory.

"This (increase in aerosols) has created a natural cooling of the planet and has partly offset the increase in surface and atmospheric temperatures due to human influence," said Lawrence Livermore climate scientist Benjamin Santer, who serves as lead author of the study.

Volcanic eruptions spew sulfur dioxide gas into the atmosphere. Large eruptions can send the gas high into the stratosphere where the gas forms tiny droplets of sulphuric acid (aerosol), which reflect a portion of incoming sunlight back into space and leads to a cooling influence in the lower atmosphere.