Volcanism and global climate change

Benjamin Franklin (1784) suggested that that year's severe winter was the result of eruptions in Iceland and Japan: Laki flow in Iceland emitted very large sulfur gas clouds, which locally decimated livestock. This was a grim time in Iceland's history. The basic correlation between volcanic eruptions and global weather pertubations had been made. The mechanism was not understood.

Mechanism by which volcanism effects climate?

What are important factors determining the amount of cooling from a large explosive eruption (discussion question)?

Historic eruptions, case histories.

Mt. Pinatubo :

Krakatoa: 1883

Tambora, Indonesia

Why are these short lived? Residence time - there are processes that remove the sulfur aerosols from the atmosphere: settling and chemical reactions. Readings describe different effects.

Climate effects of asteroid impacts:

The geologic record and the effect of volcanism on climate.

Is the rate of volcanism on the earth a constant on the earth at any time scale?

Could a volcanic eruption or series of eruptions in concert with other factors contribute to a climate shift (the last straw hypothesis)?

What is largest eruption that could happen?

Where is majority of volcanism occurring on earth at present?

K superplume event: huge Aptian-Albian (120-100 Ma) increase in ocean crust formation (75% increase over present rates). This corresponds to one of the most stable and warmest geologic periods on record. Why associated with warming and not cooling? Filtering effects of oceans? Yo-yo effect?

Is volcanism a major factor in present debate about global climate change? Should it be?

The best indicator of the range of possible future behavior is past behavior. Considering this it is useful to think of all the places that might have a paleoclimate record?

Discussion question for next time: How do the results from the boreholes compare to those of meteorologic records from last 200 years or so? Be as specific as possible. Why is it important to make such a comparison.

Readings for next time: