GHG INTRODUCTION TO GREENHOUSE GASES

Question 1

what is the IPCC?

Answer 1

intergovernmental body of the United Nations providing the world with objective, scientific information relevant to understanding the scientific basis of the risk of human-induced climate change, its risks, and possible response options

Question 2

What is the UNFCCC?

Answer 2

United Nations Framework Convention on Climate Change
- seeks for stabilisation of greenhouse gas concentrations in the atmosphere to a level that would prevent dangerous anthropogenic human-induced interference with the earth’s climate system

Question 3

global warming from fossil fuel burning may delay the next glaciation by … years.

Answer 3

500,000

Question 4

what is the Dansgaard-Oeschger cycle?

Answer 4

• rapid climate change during the last glaciation
• abrupt warming followed by near-interglacial conditions occurring in a matter of decades before a period of gradual cooling

Question 5

what is the 4-step process of the greenhouse effect?

Answer 5

1. sunlight passes through the atmosphere and warms the surface of the earth
2. infrared radiation is given off by the earth
3. most escapes to outer space and cools the earth
4. but some IR is trapped by gases in the air, thus reducing the cooling

Question 6

the greenhouse gas is … to our survival. without it, the planet would be …; …°C colder than today

Answer 6

critical
uninhabitable
30

Question 7

Why does the global warming potential of a gas vary?

Answer 7

• due to molecular structure and residence time
• N2O (0.3ppm in troposphere) > CH4 (1.8ppm) > CO2 (420ppm)
  the impact of a GHG on global warming results from a combo of…
• the compound’s infrared absorption spectrum at wavelengths not absorbed by water and CO2
• the atmospheric lifetime of a gas

Question 8

what is the order of GHG’s in terms of their contribution to the greenhouse effect, relative to CO2, starting with the lowest?

Answer 8

1. CO2 (1)
2. CH4 (34)
3. N2O (298)
4. Ozone (O3) (2,000)
5. CF4 (7,350)
6. CFC-12 (15,000)

Question 9

What is the equation for radiative forcing?

Answer 9

Incoming Energy - Outgoing Energy = Radiative Forcing
it’s expressed relative to the year 1750

Question 10

what are the factors towards global warming effects?

Answer 10

• CO2, CH4, N2O & Halocarbons
• tropospheric ozone
• black carbon from fossil fuel burning
• mineral dust (can be cooling)
• aviation (contrails and cirrus)
• solar

Question 11

what are the factors towards global cooling effects?

Answer 11

• stratospheric ozone
• sulphate
• organic carbon from fossil fuel burning
• biomass burning
• aerosol indirect effect
• land use (albedo only)

Question 12

what are the contributions of CO2, CH4 and water vapour to the greenhouse effect?

Answer 12

CO2= 9-26%
methane= 4-9%
water vapour= 36-70%