Other Greenhouse Gases

Question 1

Methane lifetime in the atmosphere

Answer 1

A little less then a decade

Question 2

What is the sink that accounts for 90% of the removal of methane?

Answer 2

The reaction with OH radicals in the atmosphere

Question 3

Why is increasing the concentration of methane in the atmosphere bad?

Answer 3

1. Much larger warming effect then carbon dioxide

2. It’s more likely to absorb thermal IR

Question 4

Methane emission sources ?

Answer 4

1. Cow farts
2. Natural ga pipeline leaks
3. Oil extraction

• anaerobic decomposition CH2O–> CH4 + CO2

Question 5

What IR light does Nitrous Oxide (N2O aka laughing gas)absorb?

Answer 5

Absorbed 8.6 micrometers through bending vibrations

Question 6

What is N2O’s atmospheric lifetime?

Answer 6

120 years

Question 7

Natural and anthropogenic sources of N2O?

Answer 7

Anthropogenic: synthetic and organic fertilizers, making of nylon
Natural: released by the oceans through soil processes, manure decomposition

Question 8

Denitrification

Answer 8

NO2–> N2

Question 9

Nitrification

Answer 9

NH(3&4) –> NO2-

• this process is more imortant

Question 10

What is the tropospheric sink for N2O?

Answer 10

There is no sink

Question 11

CFC absorption range and residence time?

Answer 11

8-13 micrometers

Long time

Question 12

Sulphur Hexafluoride

Answer 12

• better than absorbing IR than CO2
• 3200 residence time
• used in insulating gas

Question 13

Ozone

Answer 13

• natural GHG
• short tropospheric residence time
• 9-10 micrometers
• power plants, vehicle exhaust, forest fires

Question 14

What wavelength does methane absorb?

Answer 14

7. 7 micrometers, just at the edge of the atmospheric window

- angle bending vibrations