Volcanic gases from early 21st century eruptions - that form mirror-like particles in the air - may have slowed down global warming, shows research.
"In the last decade, the amount of volcanic aerosol in the stratosphere has increased, so more sunlight is being reflected back into space," said lead author Benjamin Santer, climate scientist at Laurence Livermore National Laboratory - a research and development centre founded by University of California.
This has created a natural cooling of the planet and has partly offset the increase in surface and atmospheric temperatures due to human influence, he explained.
Along with CO2, volcanoes churn out sulphur dioxide gas.
That gas turns into tiny droplets of sulphuric acid in the upper atmosphere.
Those acid particles act like tiny mirrors to reflect sunlight back into space, said a paper published in the journal Nature Geoscience.
The recent slow-down in observed surface and tropospheric warming is a fascinating detective story, Santer said in a press release.