Small volcanic eruptions over the past 20 years have been protecting the Earth from global warming, according to a new study.
Scientists have confirmed that droplets of sulphur-rich aerosols spewed into the upper atmosphere by volcanoes have been reflecting sunlight away from the Earth.
Until recently it was thought that only particularly large eruptions had any noticeable affect on the climate.
However, the new study has confirmed results from the end of last year that showed these small eruptions can have an accumulative impact on global temperature.
This could have helped decrease the global temperatures by between 0.05°C to 0.12°C over the past 15 years.
Since 1998, the warmest year on record, the steep increase in global temperatures seen during the 1990s has levelled off, failing to match computer model predictions for climate change.
This pause, or hiatus, has been blamed on weak solar activity and increased uptake of heat by the world’s oceans.
The UN’s Intergovernmental Panel on Climate Change last year concluded that the deep oceans had been responsible for absorbing an increasing amount of heat, but warned that this could not continue indefinitely.
However, in a paper published in November last year, atmospheric scientists at the Massachusetts Institute of Technology found that small volcanic eruptions in the early 21st century, which had been largely overlooked, were responsible for up to a third of the hiatus in warming.
Now researchers at the Lawrence Livermore National Laboratory, in California, have found signs of the effects from eruptions from the late 20th century and early 21st century in the atmospheric temperature, moisture and amount of sunlight reflected from the atmosphere.
They also found that the eruption of Pinatubo, a volcano on the island of Luzon in the Philippines, which last erupted in 1991, also caused a drop in tropical rainfall.
‘The fact that these volcanic signatures are apparent in multiple independently measured climate variables really supports the idea that they are influencing climate in spite of their moderate size,’ said Mark Zelinka, a climate scientist at Lawrence Livermore and one of the authors of the new study.