EAE3132 Theme 3 Observed climate change and introduction to climate models

Climate Extremes

Rare, high impact, statistically defined

Absolute threshold

Extremes are defined by a fixed threshold, impact relevant

Relative threshold

Defined by the tails of statistical distribution, not impact relevant

Extrapolation

Projection of current trends into the future

Analysis of cycles

Projection based on past cyclical behaviour: a degree of extrapolation too

Statistical forecasting

A statistical description based on past empirical data: mean, standard deviation, trend

Physical climate models and projections

Application of equations of motion of a fluid, and equations for surface changes

Climate model

Uses mathematical representations of physical laws to represent important processes in the climate system

Energy balance models

Representations of the Earth’s energy budget

Earth system models

Include representations of Earth’s geography, mode complex than EBM but many processes are still simplified

General Circulation models

Highest affordable resolution representation of 3D structure of winds and currents

Resolution

Can’t resolve the entire physics of the system

Computing power

Length of simulation, number of points, speed of processors

Parameterisation schemes

Representation of unresolved processes