Research led by scientists at from Lawrence Livermore National Laboratory in California has concluded that, despite the continuing rise of atmospheric greenhouse gas levels, global mean temperatures at the surface of the planet and in the troposphere have shown relatively little warming since 1998.
The study found correlations between observations of volcanic sulphur dioxide aerosols and satellite-based estimates of lower-tropospheric temperatures and amounts of reflected sunlight.
‘In the last decade, the amount of volcanic aerosol in the stratosphere has increased, so more sunlight is being reflected back into space,’ said Benjamin Santer, the study’s lead author. ‘This has created a natural cooling of the planet and has partly offset the increase in surface and atmospheric temperatures due to human influence.’
Santer described the recent slowdown in observed warming as ‘a fascinating detective story’. ‘There isn’t a single culprit, as some scientists have claimed,’ he said. ‘Multiple factors are implicated. The real scientific challenge is to obtain hard quantitative estimates of the contributions of each of the factors in the slowdown.’
This story was published in the April 2014 edition of Geographical Magazine
