Volcanic winter
While most volcanic ash settles to the ground within a few weeks after the eruption, impacting only the local area for a short duration, the emitted SO2 can lead to the formation of H2SO4 aerosols in the stratosphere.
[3] The subsequent dispersal of a volcanic cloud in the stratosphere and its impact on climate are strongly influenced by several factors, including the season of the eruption,[4] the latitude of the source volcano,[5] and the injection height.
[6] If the SO2 injection height remains confined to the troposphere, the resulting H2SO4 aerosols have a residence time of only a few days due to efficient removal through precipitation.
[4] The sulfate aerosol interacts strongly with solar radiation through scattering, giving rise to remarkable atmospheric optical phenomena in the stratosphere.
These phenomena include solar dimming, coronae or Bishop's rings, peculiar twilight coloration, and dark total lunar eclipses.
The eruption of a large volume of volcanic materials can enhance weathering processes, thereby lowering atmospheric CO2 levels and contributing to global temperature reduction.
The rapid emplacement of mafic large igneous provinces has the potential to cause a swift decline in atmospheric CO2 content, leading to a multi-million-year-long icehouse climate.
[22][23] Tree-ring-based temperature reconstructions, historical records of dust veils, and ice cores studies have confirmed that some of the coldest years during the last five millennia were directly caused by massive volcanic injections of SO2.
[b][27][28][29][30] For earlier periods in the Holocene, the identification of frost rings that coincide with large ice core sulfate spikes serves as an indicator of severe volcanic winters.
Sulfate concentration and isotope measurements from polar ice cores taken around the time of 74,000 years BP have identified four atmospheric aerosol events that could potentially be attributed to YTT.
[23][22][21] During this period, Earth's surface temperatures dropped below the freezing point of water everywhere,[61] and ice rapidly advanced from low latitudes to the equator, covering a worldwide extent.
[63] Geochronology dates the rapid emplacement of 5,000,000 km2 (1,900,000 sq mi) Franklin large igneous province just 1 million year before the onset of Sturtian glaciation.
[66][67] Simulations demonstrate that the increased weatherability led to drop in atmospheric CO2 of the order of 1,320 ppm and an 8 K cooling of global temperatures, triggering the most extraordinary episode of climate change in the geologic record.
