Chapter 1 Flashcards
Most important GHGs
CO2, CH4 & N2O
Global mean temp rise since 1850
0.4C - 14.5C
Global average sea level rise since 1850
20cm
Outline Greenhouse effect
- Solar radiation passes through atmosphere
- Most absorbed by surface, warming it & lower atmosphere
- Radiation re-emitted in all directions by GHG molecules, casing warming.
Why difficult to compare to natural forcing?
Poor data pre industrial revolution
Other GHGs contribute what amount compared to CO2?
2/3
Albedo meaning
amount of radiation the earth can reflect
How humans effected Albedo
- Heat reducing snow & ice & soot darkening
- Cities radiate more heat
- Grass reflects more than forests.
Aerosol & water vapor…
form clouds, influencing radiative balance
Nutrient cycle influenced by
nitrogen & phosphate fertilizers
Main human effects on
vegetation, albedo & carbon cycle
Natural warming effects
Volcanic eruptions, large but short lived effects.
Compounding effect of water vapor
Warmer air = more water vapor
Water vapor is a GHG
Warmer air causes further warming
Why cloud formation impacts uncertain?
keep heat in during night & winter
But, sun out in summer & daytime
Why ocean uncertainty?
Warming depends on complex patterns of currents.
Poor deep ocean data.
Data suggests what human impact on warming?
Indicates its unlikely warming is NOT due to human activity.
Pre-industrial main exchanges of carbon between…
atmosphere, ocean & terrestrial vegetation
(each stores carbon)
Why natural CO2 fluctuation large?
Vegetation grows in norther spring & summer,
Dies in autumn & winter.
Less land in south -> smaller impact
Human emissions smaller, but…
No counterbalance
projected 21st century warming
0.2 - 5.8C
If we burnt all FFs temperatures rise by
12C
Which warms more Artic or tropics?
Artic
Precipitation projected to increase over…
high latitudes
precipitation projected to decrease over…
subtropic
Rise in sea level from icecaps melting
4-23cm
West-Antartic iceshelf melt adds
5-6m
East-Artic melt adds
60m
