Major Differences in Regional Climate Impact Between High‐ and Low‐Latitude Volcanic Eruptions

Abstract

Volcanic eruptions impact the radiative balance of Earth's atmosphere due to scattering, absorption and reflection of radiation by volcanic aerosols. Explosive eruptions, where the volcanic plume reaches the stratosphere, have the strongest climate effect due to the volcanic aerosols preventing part of the radiation entering the troposphere, as well as the prolonged life time of stratospheric aerosols. The climate effects of large volcanic eruptions have been documented by observations. Most notably the 1991 Pinatubo eruption, which resulted in a peak cooling of the global temperature by 0.5°C 1 year after the eruption (Soden et al., 2002). However, local climate effects from the eruption due to changes in winter atmospheric circulation are thought to have been up to +4°C to −4°C depending on the region (Robock, 2000). Explosive equatorial (EQ) eruptions, such as Pinatubo, eject material into the lower stratosphere, which is then distributed to both hemispheres by the Brewer-Dobson circulation of the stratosphere (Bönisch et al., 2009). In comparison, for Northern Hemisphere high-latitude (NH) eruptions where the plume also reaches the stratosphere, the volcanic aerosols mainly stay in one hemisphere. Hence, differences in the climate effect of NH and EQ volcanic eruptions can be expected.Over the past millennium there has been a more frequent occurrence of explosive EQ eruptions injecting aerosols into the stratosphere, compared to that of NH eruptions (Sigl et al., 2015), which is probably the reason for the EQ eruptions to have been studied more intensely. The prevailing theory for the impact of EQ eruptions on atmospheric circulation is as follows (Robock, 2000). Due to the geometry of Earth, as well as the polar night, more solar radiation will be absorbed in the stratosphere at low-latitudes by volcanic

Changes in Northern Hemisphere extra-tropical cyclone frequency following volcanic eruptions

“…It is possible, that the differences in changes of the tropopause depth offer an explanation for the findings of Sjolte et al (2021) that mid-and low latitude eruptions have differing impacts on the North Atlantic Oscillation. An objection could be, that the ETCs have an impact on the depth of the troposphere themselves, and hence they cannot explain changes in the ETC distribution.…”

“…Eruption impacts on stratospheric circulation have been studied intensely (Graft et al 1993, Bittner et al 2016, DallaSanta et al 2019. In contrast, the impact of eruptions on high and mid-latitude circulation and weather has so far mostly been quantified by analysing single site proxies (Dawson et al 2007, Kuijpers andMikkelsen 2009) or large-scale circulation indices such as the Atlantic Multidecadal Oscillation (Birkel et al 2018, Mann et al 2021, the North Atlantic Oscillation (Robock 2000, Sjolte et al 2021 or the Arctic Oscillation (Stenchikov et al 2002, Christiansen 2008. Although these indices do correlate with surface weather patterns (Laurila et al 2021), they express only temporally and spatially integrated information.…”

Impact of volcanic eruptions on extratropical atmospheric circulations: review, revisit and future directions

“…For high-latitude volcanic eruptions, Oman et al (2005) reported rather minor responses of Arctic polar vortex and unclear surface anomalies following the Katmai eruption which occurred at 58 • N. In contrast, Zambri et al (2019) showed negative NAO after the 1783 Laki eruption which occurred at 64 • N. Sjolte et al (2021) additionally presented the appearance of positive and negative NAO to low-and NH high-latitude volcanic eruptions, respectively, during the last millennium from climate reconstructions. In This result indicates that extratropical circulation and surface climate responses to volcanic eruptions are dependent on the latitude of volcanic eruptions.…”