Small volcanic eruptions slowing down global warming?

Small volcanic eruptions might eject more of an atmosphere-cooling gas into Earth's upper atmosphere than previously thought, potentially contributing to the recent slowdown in global warming, contends a new study.

Small volcanic eruptions that occurred between 2000 and 2013 have deflected almost double the amount of solar radiation previously estimated, the findings showed.

By knocking incoming solar energy back out into space, sulphuric acid particles from these recent eruptions could be responsible for decreasing global temperatures by 0.05 to 0.12 degrees Celsius since 2000, the study noted.

"It is the best analysis we have had of the effects of a lot of small volcanic eruptions on climate," said Alan Robock, a climatologist at Rutgers University who was not involved in the study.

The new study combined observations from ground, air and space-based instruments to better observe aerosols in the lower portion of the stratosphere.

These new data could help to explain why increases in global temperatures have slowed over the past 15 years, a period dubbed the 'global warming hiatus', according to the study authors.

The warmest year on record is 1998. After that, the steep climb in global temperatures observed over the 20th century appeared to level off.

Scientists have long known that volcanoes can cool the atmosphere, mainly by means of sulphur dioxide gas that eruptions expel.

However, previous research had suggested that relatively minor eruptions-those in the lower half of a scale used to rate volcano "explosivity" - do not contribute much to this cooling phenomenon.

The study is forthcoming in the Geophysical Research Letters.