1. Gases that escape in the greatest abundance from volcanoes are:
-water vapor
-carbon dioxide
-hydrogen chloride
-nitrogen
-sulfur dioxide

2. Volcanoes & The Atmosphere
Volcanic gases play an important role in the Earth System. Carbon dioxide, on the early earth, was emitted from volcanoes and converted to oxygen by photosynthetic algae.

3. Volcanoes & The Atmosphere
Volcanic activity gave the early Earth much of it’s atmosphere. (carbon dioxide and nitrogen).

4. Volcanoes & The Water Cycle
Water vapor is essential to the Earth system. Most of Earth’s surface water seems to have been released from the Earth’s interior by volcanoes.

5. Volcanoes and the Earth System
CO2
H2O
Volcanic emissions
remains
photosynthesis
condensation N2 O2
oceans
99% of atmosphere
Volcanoes produced the atmosphere and the oceans

6. Cosmos

7. Turn to your neighbor and discuss the following questions:
Be prepared to share your answer with the class.
Which gases are emitted from a volcano in the greatest amounts?
Oxygen is not one of the gases emitted from a volcano. On the early earth, how was oxygen created?
3. Volcanoes are responsible for creating earth’s atmosphere and oceans. Explain how the oceans were created.

8. Dangerous Gases
High concentrations of carbon dioxide near a volcano are hazardous because they cause people and animals to suffocate.

9. Lake Nyos - Cameroon

10. If the air that we breath has more than 10% CO2 it becomes deadly because it displaces the Oxygen that we need for respiration.
Lake Nyos, Cameroon, is a very deep lake within a volcanic crater.
The lake is so deep that hydrostatic pressure forces CO2 to remain at the lake bottom.
When the pressure of the CO2 exceeds a certain limit the gas rapidly bubbles up out of the lake and flows as an invisible gas cloud down the adjacent slopes.
On August 16, 1986 such a gas release flowed 19 km suffocating 1,700 people along its route.

11. Lake Nyos - Cameroon

12. Lake Nyos - Cameroon

13. Lake Nyos - Cameroon

14. Lake Nyos - Cameroon
The fountain in the background lifts CO2 up to the surface so that it no longer accumulates.

15. Mammoth Mountain. California
Mammoth Mountain is a relatively young volcano that is emitting large volumes of CO2.
Gas concentrations in the soil in some areas near the mountain are high enough to kill trees and small animals.

16. Mammoth Mountain. California

17. Acid Rain
Formation of acid rain (from sulfur dioxide SO2) can cause water contamination and plant damage
Prevailing winds can blow gases thousands of kilometers away

18. Climatic Effects

19. Global Climate Change
SO2 (sulfur dioxide) in the upper atmosphere. reduces incoming solar radiation.
SO2 from an eruption forms tiny droplets of sulfuric acid in the upper atmosphere.
The droplets significantly increase global albedo…..a negative radiative forcing that leads to cooling.
Mt. Pinatubo (1991) released 22 million metric tons of SO2 and reduced the Earth’s average temperature by 0.5 degrees Celsius in the year following the eruption.

20. Tambora & ‘the year without a summer’
Largest known historic eruption → 200 Mt sulphate aerosol in stratosphere
1816 one of coldest northern hemisphere summers of last 600y
Extreme weather
June snow in eastern North Am.
Summer killing frosts led to near total failure of crops in New England
Europe Summer T 3ºC cooler than average
Cooling effect continued for 3 years
‘last great subsistence crisis in western world’ bread riots; famine; typhus & cholera

21. Tambora & ‘the year without a summer’

22. Clicker Time
1. Carbon Dioxide in the atmosphere can be dangerous because:
a. It can cool down the planet
b. It can warm up the planet
c. It can kill plants and animals if the air is more than 10% carbon dioxide
d. Both choices b and c
e. None of the above

23. Clicker Time
Sulfur dioxide being released into the atmosphere could have which of the following effects?
a. It can cool down the planet
b. It can warm up the planet
c. It can create acid rain
d. Both choices a and c
e. None of the above