lecture 10 Climate change and other planetary boundaries 2 Flashcards
IPCC AR5 Representative Concentration Pathways (RCPs)
Four scenarios, long term to 2300, short term to 2030
RCPs start with scenarios for concentrations not emissions
Facilitates parallel process (instead of linear economic->emissions->concentrations->impacts)
- earth scientists look at concentration impacts on systems
- social scientists (using integrated assessment models) look at socio-economic processes that could lead to these.
Modelling climate change with General Circulation Models (GCMs)
3-dimensional GCM’s discretise the equations for fluid motion and energy- transfer and integrate these forward in time.
Grid of ~150km resolution across globe.
Parameterise small scale processes e.g. convection
Coupled atmosphere-ocean GCMs (AOGCMs) e.g. HADCM3
Precipitation change :
current to 2050
Large decreases in the N of the Basin.
Increases in the W and Andes,
Decreases elsewhere.
Temperature change :
current to 2050
Increases throughout but
especially in the E.
Increases throughout but particularly strong in the NE.
Regional Climate Models (RCMs)
For impacts analysis. RCMs work by increasing the resolution of the GCM in a small, limited area of interest.
The full GCM determines the very large scale effects of changing greenhouse gas concentrations, volcanic eruptions etc. on global climate.
The climate (temperature, wind etc.) calculated by the GCM is used as input at the edges of the RCM. RCMs project weather and climate information (such as precipitation) at resolutions as fine as 50 or 25km.
Climate change: projection uncertainty
Uncertainties cascade through the systems
So these are not predictions but projections (plausible futures)
Uncertainties will reduce over time with more data/work
But there are still unknown unknowns (thresholds, shocks)
Need to be adaptable and resilient as prediction is impossible
