Lecture 23: Modelling Climate Change

Question 1

What is a predictive model?

Answer 1

Complex math-based computer programs which use past and present conditions to determine likely future conditions

Question 2

What is a general circulating model?

Answer 2

GCMs utilize math models to simulate the circulation of energy/mass between the atmosphere and oceans

Question 3

What are common variables in GCMs?

Answer 3

• air temp
• vap pressure
• solar radiation
• air pressure
• albedo

Question 4

What is a scale of a model?

Answer 4

How large or small of an area is covered by the model (mainly broad to give planetary averages rather than details on specific areas)

Question 5

What is downscaling?

Answer 5

mathematical models used to convert global data to small-scale local topography

Question 6

What is a regional circulating model

Answer 6

A circulating model on the scale of a country (or smaller)
Not generating new data, only downscaling general circulating model data

Question 7

What is uncertainty?

Answer 7

the parts of a model for which we have insufficient data (known or unknown)

Question 8

What are common sources of uncertainty?

Answer 8

• not knowing all variables that affect a process
• determining the importance of each variable
• data changing over a period of time violating an assumption of a predictive model

Question 9

What are earth system models?

Answer 9

a new class of general circulating model that incorporates biogeochemical cycles (transfer of chemicals between biotic and abiotic reserves)

Question 10

What is RCP 1.9?

Answer 10

limits global warming to below 1.5˚C (considered unlikely)

Question 11

What is RCP 2.6?

Answer 11

CO2 emissions start declining in 2020 and reach zero at 2100 (best case scenario)

Question 12

What is RCP 4.5?

Answer 12

CO2 emissions peak in 2045 due to oil (most likely to occur)

Question 13

What is RCP 8.5?

Answer 13

CO2 emissions do not peak before 2100 (what happens if we continue how we are)

Question 14

How do we verify if our models are accurate?

Answer 14

Hindcasting: using past known conditions to calibrate a model and see if it “predicts” current conditions

Question 15

What are specific uncertainties in current GCMs?

Answer 15

some global systems are still not completely understood:
- clouds
- atmospheric snow and ice formation
- jet stream
- major unpredictable events (volcanos, sudden collapse of carbon sinks…)

Question 16

How do we attempt to model cloud systems?

Answer 16

Parametrization: average a variable over a large area

Convective-permitting: simulate on an exceptionally small scale to model the known cloud formation patterns