Impact of global warming on the rise of volcanic plumes and implications for future volcanic aerosol forcing

Abstract

Volcanic eruptions have a significant impact on climate when they inject sulfur gases into the stratosphere. The dynamics of eruption plumes is also affected by climate itself, as atmospheric stratification impacts plumes' height. We use an integral plume model to assess changes in volcanic plume maximum rise heights as a consequence of global warming, with atmospheric conditions from an ensemble of global climate models, using three representative concentration pathways (RCP) scenarios. Predicted changes in atmospheric temperature profiles decrease the heights of tropospheric and lowermost stratospheric volcanic plumes and increase the tropopause height, for the RCP4.5 and RCP8.5 scenarios in the coming three centuries. Consequently, the critical mass eruption rate required to cross the tropopause increases by up to a factor of 3 for tropical regions and up to 2 for high‐latitude regions. A number of recent lower stratospheric plumes, mostly in the tropics (e.g., Merapi, 2010), would be expected to not cross the tropopause starting from the late 21st century, under RCP4.5 and RCP8.5 scenarios. This effect could result in a ≃5–25% decrease in the average SO2 flux into the stratosphere carried by small plumes, the frequency of which is larger than the rate of decay of volcanic stratospheric aerosol, and a ≃2–12% decrease of the total flux. Our results suggest the existence of a positive feedback between climate and volcanic aerosol forcing. Such feedback may have minor implications for global warming rate but can prove to be important to understand the long‐term evolution of volcanic atmospheric inputs.

Turbulent Entrainment Into Volcanic Plumes: New Constraints From Laboratory Experiments on Buoyant Jets Rising in a Stratified Crossflow

“…Third, for model 3, the range of 6–8 found for in Figure is in remarkable agreement with the results of Aubry et al (), even though this previous study used an analytical scaling (relating plume height to source conditions and environmental parameters) and plume height measurement to constrain this ratio.…”

Climate Feedback on Aerosol Emission and Atmospheric Concentrations

“…Kipling et al [70] emphasized the importance of convective mixing controlling the aerosol vertical profile for all types except dust. Simulations using a plume model to assess future changes in volcanic aerosol transport suggest that a future increase in tropopause height due to strengthened convection will lead to reduced transport of volcanic aerosol into the stratosphere reducing its lifetime and cooling effect [71].…”

Reduced cooling following future volcanic eruptions

“…For example, during the last glacial maximum (LGM, 21,000 years BP) there was a global 2-4-fold increase in the dust cycle intensity (Lambert et al 2015), which would have increased the albedo of the troposphere in a similar manner as for the future increase in manmade aerosols. Conversely, the global cooling of 3-5 • C relative to the pre-industrial during the LGM (Shakun et al 2012) would have lowered the tropopause by up to 1.5 km, so that smaller more frequent eruptions would more easily penetrate the stratosphere, following the mechanism outlined by Aubry et al (2016). Summers are nearly ice-free under RCP6 in 2050 in these simulations.…”

“…Although Aubry et al (2016) show that the amount of volcanic sulphur dioxide reaching the stratosphere is sensitive to climatic warming, they showed that this is effect is weakest for the largest eruptions. Therefore, it seems that for an eruption of the magnitude of Tambora, this is probably less important.…”

“…The interaction between tropospheric planetary albedo and the magnitude of the direct volcanic aerosol radiative forcing has not been reported previously to our knowledge. This diminished volcanic response may, depending on the eruption magnitude, be further enhanced by the proposed effect of the tropopause height on the penetration of smaller eruption plumes (Aubry et al 2016).…”