(July 9, 2015) Volcanic aerosols have acted during the last 10 years as a
natural umbrella to slow down global temperature increase from greenhouse gases
Although global concentration of greenhouse gases in the
atmosphere has continuously increased over the past decade, the mean global
surface temperature has not followed the same path. A team of international
reseachers, KIT scientists among them, have now found an explanation for this
slowing down in global warming: the incoming solar radiation in the years
2008-2011 was twice as much reflected by volcanic aerosol particles in the
lowest part of the stratosphere than previously thought. The team presents
their study in Nature Communications (DOI: 10.1038/ncomms8692).
For the lowest part of the stratosphere – i. e. the layer
between 10 and 16 kilometres – little information was available so far, but now
the international IAGOS-CARIBIC climate project combined with satellite
observations from the CALIPSO lidar provided new essential information.
According to the study, the cooling effect due to volcanic eruptions was
clearly underestimated by climate models used for the last Intergovernmental
Panel on Climate Change (IPCC) report. Led by the University of Lund, Sweden,
and supported by the NASA Langley Research Center, USA, and the Royal
Netherlands Meteorological Institute, three major German atmospheric research
institutes were also involved: the Max Planck Institute for Chemistry in Mainz
(MPI-C), the Leibniz Institute for Tropospheric Research in Leipzig (TROPOS)
and the Karlsruhe Institute of Technology (KIT). Since more frequent volcanic
eruptions and the subsequent cooling effect are only temporary the rise of
Earths’ temperature will speed up again. The reason is the still continuously
increasing greenhouse gas concentration, the scientists say.