Radiative forcing Flashcards
What does the global warming potentially (GWP) account for?
- radiative forcing for a known amount of gas
- emission rate of gas
- lifetime of the gas in the atmosphere
- indirect effects of the gas on radiative forcing
What is the global warming potential (GWP)?
The estimated forcing at some future time based on emissions now. It accounts for the radiate forcing for a known amount of gas, the emission rate of the gas, the lifetime of the gas in the atmosphere and any indirect effect of the gas on radiative forcing.
What is a well mixed greenhouse gas?
Gases for which the timescale of removal is much longer than the mixing time of the atmosphere
How long is the lifetime of methane?
12 years
What are some examples of well-mixed greenhouse gases?
Carbon dioxide, Methane, Nitrous oxide, Chlorocarbons
How much of total radiative forcing does CO2 contribute to?
60%
How much has atmospheric concentration of CO2 increased since 1750-2005?
From 280ppm to 380ppm (36%)
How much have CO2 emissions increased annually from 1999-2005?
3% annual increase
How much of methane emissions are anthropogenic?
50%
What contribution does methane have to radiative forcing?
20%
What are some natural sources of methane?
Ocean, Termites, Wetlands,
What are some anthropogenic sources of methane?
Biomass burning, landfill, domestic sewage, animals waste, fossil fuels, animal husbandry, paddy fields
What is the lifetime of CO2?
Variable (>100)
What is the GWP of CO2 on a 20 year time scale?
1
What is the GWP of methane on a 20 year time scale?
62
What is nitrous oxide?
Byproduct of natural and agricultural ecosystems (biotic processes in soil)
What are some sources of nitrous oxide?
- increased fertiliser use
- nylon production
- nitric acid production
- vehicular emissions
How long is the lifetime of nitrous oxide?
114 years
How much stronger is nitrous oxide compared to CO2?
x300 stronger per kg
What is the GWP of nitrous oxide on a 20 year time scale?
275
What is a halocarbon?
A man-made compound containing carbon and either chlorine, bromine or fluorine
What are some example of halocarbons?
CFCs, Halons, HCFCs (hydrochlorofluorocarbons), HFCs (hydrofluorocarbons)
What is the lifetime of halocarbons?
11.9 years (HCFC-22) up to 260 years (HFC-23)
What is the radiative forcing of all well-mixed greenhouse gases since pre-industrial times?
2.64 +- 10% (IPCC AR4)
What was the abundance of methane in 2005?
1774 ppb
What is tropospheric ozone?
A pollutant produced by photochemical reactions involving hydrocarbons and nitrogen oxides typical of biomass burning and urban pollution
How much of total ozone is found in the troposphere?
1/6
Why is ozone not retrievable from ice core?
It is too short lived
What is the relationship between solar forcing since 1750 and anthropogenic forcing?
Solar forcing has likely been 5 times smaller than total anthropogenic forcing
What is the GWP of methane in 20 years compared to CO2?
60
