Emissions from volcanic eruptions likely played a role in offsetting the global warming from greenhouse gases over the past 10 to 15 years.
The recent 'slow-down' of global warming is partly due to an increase of volcanic aerosols into the stratosphere during this century, according to the new research from the Lawrence Livermore National Laboratory.
"This (increase in aerosols) has created a natural cooling of the planet and has partly offset the increase in surface and atmospheric temperatures due to human influence," said Lawrence Livermore climate scientist Benjamin Santer, who serves as lead author of the study.
Volcanic eruptions spew sulfur dioxide gas into the atmosphere. Large eruptions can send the gas high into the stratosphere where the gas forms tiny droplets of sulphuric acid (aerosol), which reflect a portion of incoming sunlight back into space and leads to a cooling influence in the lower atmosphere.
Another excerpt from the LLNL study about how they came up with their conclusion...
The researchers performed two different statistical tests to determine whether recent volcanic eruptions have cooling effects that can be distinguished from the intrinsic variability of the climate. The team found evidence for significant correlations between volcanic aerosol observations and satellite-based estimates of lower tropospheric temperatures as well as the sunlight reflected back to space by the aerosol particles.
I will say that it seems like we there has been an uptick in volcanic activity over the past decade, though I do not readily have the data to support that. However, I know a lot depends on the volume of emissions and how high it gets up into the atmosphere.
It is a fact that major eruptions that eject a large volume of sulfur dioxide into the stratosphere and especially those located in the tropical regions can produce a sudden, but significant drop (negative forcing) in global temperature for a short period of time. (see graph below)
No surprise, August 2016 was the warmest August on record for global land/ocean surface combined, according to NOAA.
For an unprecedented 11th straight month a new record high monthly global temperature has been set.
There are major metropolitan areas along the coast that are actually sinking at a higher rate than oceans are rising.
New research looks at the influence of climate change on mid-latitude storm tracks.
As the planet warms there may be less impact on drought than previous studies have shown.
Climate model projections can become quite uncertain at more localized levels.