1. Climate Modeling General Circulation Models
Bruno Tremblay
McGill University

2. Model Components
Atmosphere

3. Model Components
Atmosphere
Ocean

4. Model Components
Atmosphere
Ocean
Vegetation

5. Model Components
Atmosphere
Ocean
Vegetation
Sea ice

6. Model Components Atmosphere Ocean Vegetation Sea ice Surface Hydrology
Ice sheets?
Aerosols?

7. Model Grid
Resolution
Convergence of Meridian

8. Then What?

9. Conservation Laws Mass Energy Momentum x + y = 3 x – y = 1 x = ? y = ?
30,000 CPU unit to run these models, GCM are developed in Boulder, GFDL, Canada, France, etc
x + y = 3
x – y = 1
x = ?
y = ?

10. Diagnostic Variables
Atmosphere: velocity, temperature, humidity, pressure
Ocean: velocity, temperature, salinity
Ice: velocity, thickness, concentration
Vegetation:
Hydrology:

11. Initial Conditions

12. Ocean Model Cube Sphere

13. Atmosphere Model

14. Ice Model

15. How do we run the models?

16. Climate Forcing Specified or Calculated? Solar activity: included
Volcanoes: specified
Aerosol from chimney: specified
Ozone hole: calculated; but CFC concentration are specified
Land use change: specified
Contrails from airplane: not included.

17. Emission Scenarios

18. Emission Scenarios A1 – homogeneous world:
Rapid economic growth
Global population peaks in mid-century and declines thereafter
Rapid introduction of new and more efficient technologies.
A2 – heterogeneous world – preservation of local identities:
Poor and rich still exist.
continuously increasing population.
B1 – same as A1:
Reductions in material intensity
Introduction of clean and resource-efficient technologies.
B2 – same as A2:
local solutions to economic, social and environmental sustainability

19. Global Mean Surface Temperature GFDL

20. Dependence on Initial Conditions

21. Forced vs Natural Variability
Do several simulations
Take the ensemble Mean