Climate modelling 101

Question 1

What are climate models and why are they important?

Answer 1

Climate models are computer programs that simulate how the climate has changed in the past and how it will change in the future.

Question 2

The term “climate system” refers to…

Answer 2

the many elements that contribute to creating a climate in a particular place or region. Components include the atmosphere and oceans, the land, ice, and biosphere (plant and animal life), as well as cities and other parts of the “built environment.”

Question 3

Uses of climate modelling?

Answer 3

Farmers
Mayors of large cities
Energy sector and water managers
Insurance companies
National security sector

Question 4

Why is simplification essentiaL?

Answer 4

Real climate is too complex to portray.
Simplification represents a
trade-off between complexity and computing flexibility.

Question 5

In large models such as 3-D models of the atmosphere, a grid cell is measured in

Answer 5

degrees of lat

and long – that may be 100’s of km2 per cell.

Question 6

What do parameterisations represent?

Answer 6

Processes by simplified and thus inaccurate equations, or empirically-derived values
(for example, the process of cloud formation).

Question 7

What can simplify the

model and save computing time?

Answer 7

Specification of a value for a variable rather than deriving it interactively.
The effect of this is to suppress feedbacks (the ocean is unreactive to changes generated as the model runs).

Question 8

What is a key limitation of Global Climate Models?

Answer 8

The fairly coarse horizontal resolution (grids).

Question 9

There are three possible solutions to the problem of course resolution in GCMs:

Answer 9

Run the full GCM at a finer resolution.
Use statistical techniques to ‘downscale’ the coarse.
Embed a Regional Climate Model (RCM) in the GCM.

Question 10

How do Regional Climate Models (RCMs) work?

Answer 10

by increasing the resolution of the GCM in a small, limited area of interest.