BIO220H1 Lecture Notes - Numerical Weather Prediction, Primitive Equations, Sea Level Rise
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Lecture 22 BIO220 Role of Greenhouse Gases in Climate change
Ice age: alternated glacial, interglacial periods
Long-term prediction: ice age continues, exit current interglacial in 10-50 thousand years
4 pioneers of climate prediction (developed models of climate change)
•Tyndall, Arrhenius, Bjerknes, Richardson
Tyndall measured how different gases absorb radiation
“Greenhouse effect” of water vapor
Arrhenius calculated effect of CO2 as greenhouse gas
•X2 [CO2] = increase by 4°C
•Glacial <-> interglacial due to CO2
•Increased coal burning = fend off next ice age
Bjerknes “primitive equations” to model weather
Richardson use equations to calculate numerical weather prediction
ENIAC’s breakthrough prediction: 24hrs of weather in 24hrs.
Weather Climate
•Can’t predict weather far in advance (chaotic nature)
•Climate = statistics of weather, predictable
•Assess predictive ability via backward prediction (compare to past records,
“hindcasting”)
Multiple models: intergovernmental panel on climate change
•Different groups in various countries on
oModel building
oCollect data on past climates
oValidation, “signatures” of causes
•IPCC by UN
oAvert “alarmist” projections by independent scientists
oDoesn’t conduct research; provides protocols, reviews to assess which
results robust, consistent and best supplemented by data; neutral with
respsect to policy
oReports based on peer-reviewed literature
Albedo “reflectivity” in energy balance
•Climate colling associated with uplift of mountain ranges, creation of new snowy
regions