Effect of volcanic eruptions significantly underestimated in climate projections

There are many things under and overestimated or wrongly represented by climate models! To what extent are they junk? There are too many things we still do not understand very well about climate!

Global Warming hoax and Climate Change religion in a nutshell

"... volcanoes do play an important role in the global climate system. When volcanoes erupt, they can spew sulphur gases into the upper atmosphere, which forms tiny particles called aerosols that reflect sunlight back into space. For very large eruptions, such as Mount Pinatubo in 1991, the volume of volcanic aerosols is so large that it single-handedly causes global temperatures to drop. ...
Standard climate projections ... overlook the effects of small-magnitude eruptions. ... but smaller eruptions are too small to be detected in ice-core records ...
“We found that not only is volcanic forcing being underestimated, but small-magnitude eruptions are actually responsible for as much as half of all volcanic forcing,” ..."

From the (structured) abstract:

"Standard climate projections represent future volcanic eruptions by a constant forcing inferred from 1850 to 2014 volcanic forcing. Using the latest ice-core and satellite records to design stochastic eruption scenarios, we show that there is a 95% probability that explosive eruptions could emit more sulfur dioxide (SO2) into the stratosphere over 2015–2100 than current standard climate projections (i.e., ScenarioMIP). Our simulations using the UK Earth System Model with interactive stratospheric aerosols show that for a median future eruption scenario, the 2015–2100 average global-mean stratospheric aerosol optical depth (SAOD) is double that used in ScenarioMIP, with small-magnitude eruptions (<3 Tg of SO2) contributing 50% to SAOD perturbations. We show that volcanic effects on large-scale climate indicators, including global surface temperature, sea level and sea ice extent, are underestimated in ScenarioMIP because current climate projections do not fully account for the recurrent frequency of volcanic eruptions of different magnitudes.

Key Points

• There is a 95% chance that the time-averaged 2015–2100 volcanic SO2 flux from explosive eruptions exceeds the time-averaged 1850–2014 flux
• Standard climate projections very likely underestimate the 2015–2100 stratospheric aerosol optical depth and volcanic climate effects
• Small-magnitude eruptions (<3 Tg SO2) contribute 30%–50% of the volcanic climate effects in a median future eruption scenario

Plain Language Summary

Climate projections are the simulations of Earth's climate in the future using complex climate models. Standard climate projections, as in Intergovernmental Panel on Climate Change Sixth Assessment Report, assume that explosive volcanic activity over 2015–2100 are of the same level as the 1850–2014 period. Using the latest ice-core and satellite records, we find that explosive eruptions could emit more sulfur dioxide into the upper atmosphere for the period of 2015–2100 than standard climate projections. Our climate model simulations show that the impacts of volcanic eruptions on climate, including global surface temperature, sea level and sea ice extent, are underestimated because current climate projections do not fully account for the recurrent frequency of volcanic eruptions. We also find that small-magnitude eruptions occur frequently and can contribute a significant effect on future climate."

Effect of volcanic eruptions significantly underestimated in climate projections | University of Cambridge Researchers have found that the cooling effect that volcanic eruptions have on Earth's surface temperature is likely underestimated by a factor of two, and potentially as much as a factor of four, in standard climate projections.

Climate Projections Very Likely Underestimate Future Volcanic Forcing and Its Climatic Effects (open access)