volcano climate effects III Flashcards
how do volcanic eruptions have short-term impacts on global average temperatures?
what gas / chemical element has the greatest impact on climate during shorter time scales?
sulfur
what are the short-term effects of volcanoes on the climate?
very large eruptions inject aerosols and ash into stratosphere (no weather to remove)
- duration of eruption can matter: shorter in the troposphere, if eruption continues for weeks, months or the year, it is constantly replenishing that in the troposphere, making it have similar impacts
- sulfur is hydrophilic (loves water), which forms reflective aerosols (high albedo: 1), which scatter and absorb incoming solar radiation
- ash has more mass, short resonance time, not a lot emitted into stratosphere
what are SAGE satellites?
measure optical depth (how easily light penetrated through stratosphere to get to the surface)
- increase optical depth = harder for incoming radiation to get through
where is optical depth greatest?
in the tropics
why did optical depth of the atmosphere thicken?
sulfate aerosols and gas
do larger eruptions have greater impacts? what variable effect how catastrophic an eruption is
not necessarily !
1. time of year
2. location (hemisphere vs equator)
3. weather patterns
4. volatile content
5. eruption style and length
most large eruptions are _______, but _______ eruptions have a much higher sulfur content?
felsic; mafic
what are the long term effects of super eruptions?
NO LONG TERM CHANGE because it is still a single injection and residence time of sulphate aerosols are limited
what are the hypothesized effects of super eruptions?
- speeding the onset of glaciation
- bottleneck effect in human lineage
- massive tropical ozone depletion
how can we tell how much sulfur is injected into the atmosphere?
ice cores: deposited and conserved
are volcanoes the smallest or largest contributor to short-term natural climate variability?
largest!
what will happen if you have multiple closely spaced together eruptions?
- more persistent climate perturbation because cooling may be extended, learning to amplification by climate feedback
- little ice age
how is a little ice age created (steps)?
- triggered / intensified by multiple eruptions
- sulfate records show many eruptions prior and into ice age
- sea ice is less likely to melt
- reflectivity of northern latitudes stays high
- grow more sea ice the following year
- increase albedo, reflect more solar radiation back into atmosphere, cooler temp
in hunga tonga- honga ha’apai, what made that eruption so catastrophic?
evaporated enormous amounts of water, despite having a small sulfur content
increased water vapor content into the stratosphere
estimated to raise global average temperature
water vapor is an effective..?
greenhouse gas!
what are large igneous provinces (LIPS)?
- large volumes of (mostly) mafic magmas were generated and extruded onto the landscape
- form independently of plate setting
- found on continents, in ocean, along margins between the two, within plate boundaries or at plate boundaries
- generally caused by hot spots / mantle plumes
what specific places are large igneous provinces?
continental flood basalts
volcanic rifted margins
oceanic plates
ocean basin flood basalts
what are the long-term climate effects of volcanoes?
- emit CO2
- CO2 pumped into atmosphere consistently for a long time
- global warming
when the atmosphere is cooling, ________ gas is produced. when the atmosphere is warming, ______ gas is produced
sulfate; CO2
persistent eruptions on LIPS may lead to what climate issues?
- ocean acidification (CO2)
- ocean anoxia (caused by acidification, eruptions lead to fertilization, which leads to plumes, which leads to anoxia)
- acid raid (sulfur)
- gas and light block impact on terrestrial ecosystems (photosynthetic shutdowns)
out of the big 5 mass extinction events, what do most of them have in common?
LIPS volcanic eruption
peak extinction events are associated with what characteristics?
- specific eruption pulses
- shorter overall duration
- siberian traps had the greatest impact (burnt through large coal deposits, and burnt large amounts of fossil fuels)
what features of major extinction events do LIPS explain?
- loss of carbonate deposits in the ocean (acidification)
- negative carbon isotopic excursions (thermogenic greenhouse gas: methane) and persistent instability
- spikes in metal deposits
- other isotopic excursions (sulfur, mercury, nitrogen)
what is the major reason for long-term climate change?
carbon cycling
how does carbon cycling occur?
- dissolution of CO2 in rain, becomes slightly acidic
- calcium + magnesium silicates do not re-form on land, most material in ocean
- calcium ions utilized by shell produces that bind CO2 to something more solid
- ongoing exchange of CO2 between ocean and atmosphere
silicate weathering on land + carbonate precipitation in the sea = natural carbon sequestration
what would happen if there was no return of CO2 to the atmosphere in carbon cycling?
take an extremely long time to deplete “short-term” cycle of carbon
carbon dioxide moves through ocean, biosphere, atmosphere, by a certain proportion of carbon atoms are sucked out and put into rock record (sequestered)
what is the carbonate-silicate geochemical cycle?
plate tectonics keep the earth alive
what is carbonate metamorphism?
reverse of silica weathering, carbonate precipitation and ocean-atmosphere exchange
releasing carbon, erupted through volcanoes
what are the steps of the carbonate-silicate geochemical cycle?
- carbon bearing rocks subducted
- undergo metamorphism
- sufficiently high temperature reached
- subducted mantle-derived CO2 return to ocean and atmosphere through mid-ocean ridges and volcanoes
how did we get out of snowball earth?
weathering was taken out of equation (not much CO2 out of atmosphere), but volcanoes still erupting and returning CO2 into the atmosphere
