Download PowerPoint explanation of volcanic impact on climate

Volcanoes and Climate
The Earth’s Energy (Radiation) Budget
Santa Maria
1902
1963
Agung
1982 El
Chichon
0
1992
Pinatubo
Atmospheric Stability
• Many things can cause air to rise
• As it rises, the pressure falls and the air cools
• If the air is then warmer than the surrounding
air, it carries on rising – unstable.
• If the air is colder than the surrounding air, it
sinks back to where is came from – stable.
• The stratosphere is always very stable – but
explosive volcanic eruptions can blast material
up into the stratosphere.
• Once in the stratosphere, the stability means
that the volcanic materials tends to stay there
for several years.
Explosive volcanoes and latitude
Tropospheric circulation
Stratospheric circulation
For maximum effect a volcano should be…
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Explosive
Low latitude
Effects are greater over land than over sea
Northern hemisphere summer season
Lots of Sulphur dioxide emitted.
Volcanic forcing of
climate over the past
1500 years: An
improved ice corebased index for
climate models 2008,
Chaochao Gao, Alan
Robock, and Caspar
Ammann
Volcanoes and their effect on climate
David Viner & Phil Jones
•
•
•
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Effusive or small volcanoes
- e.g. Bárðabunga, 2014-15
Explosive volcanoes
Super volcanoes or intense volcanic activity
Snowball Earth (pre-Cambrian)
Super volcanoes - any volcano capable of producing a
volcanic eruption with an ejecta mass greater than 1015
kg
- Toba, Sumatra (74,000 years ago), preceded major
glaciation
- Yellowstone (640,000 years ago), 5°C global cooling
Laki & Grímsvötn, 1783-84
• Lasted for eight months during 1783 to 1784, and produced one of
the largest basaltic lava flows in historic times
• The release of sulphur gases during fountaining produced an acid
haze (aerosol) which spread widely and had a considerable
environmental, and possibly climatic, impact on the Northern
Hemisphere.
• Troposphere, not stratosphere
• Fire-fountains of magma reached 1.4km, ash reached 9-13km
• The quantity of SO2 released was comparable to the total annual
present-day anthropogenic input to the atmosphere
Laki & Grímsvötn, 1783-84
• During the explosive phases, the atmosphere over Iceland
became loaded with fine ash and sulphuric acid droplets.
• Grass growth was stunted, 50% of grazing livestock died and
22% of Icelanders died.
• Haze or dry fog was reported over much of the Northern
Hemisphere, blood red sunsets – affected vegetation, animals
and people
• Summer of 1783 was warm, 1784-1786 was colder than
usual, but was it due to the volcano?
• Linked to famine and plague in middle east, virtual dying out
of Inuit in NW Alaska
• Did the aerosol reach the stratosphere?
• Food poverty was a major factor in the build-up to the French
revolution of 1789
Eyjafjallajökull, 2010
Volcanoes and Climate Change?
Climate Change
Less Ice
Less Pressure
More magma
generation
http://www.yalescientifi
c.org/2015/11/icelandsvolcanic-activity-toincrease-from-climatechange/
Additional Sources:
https://www.wunderground.com/climate/volcanoes.asp