Lecture 10 Climate change and other planetary boundaries

Question 1

The science and policy of climate change is based on four major pieces of evidence

Answer 1

1] Emissions of CO2 and other GHGs are increasing

[2] Atmospheric concentrations of CO2 and other GHGs are increasing

[3] Global temperatures are on the increase

[4] Atmospheric theory and General Circulation Models (GCMs)
indicate that, if CO2 continues to increase, so will temperature.
This will affect other climatic variables in complex ways

Question 2

So far observed atmospheric warming likely slowed:

Answer 2

By oceans taking up heat

By volcanic activity (offset)

By tropospheric aerosols from the same pollution

Question 3

Climate change: observed and modelled

Answer 3

Not all the simulated projections are being observed in the measured data and we do not know why

Question 4

But, How do we make these climate projections?

Climate change modelling I: IPCC AR4 scenario generation

Answer 4

Understand changes in economy etc

Understand impacts of GHG concentrations

Model climate

Look into impacts

Question 5

Climate change scenarios

Answer 5

Represent an image of future
Neither forecast nor prediction (projection)

Each scenario is one possible future

Set of scenarios for possible future developments of a complex system

Useful tool for (not fully understood) complex systems, whose prediction is impossible e.g population growth, use of fossil fuels and GHG emissions