1. Global Climate Change Prediction and Feedback mechanisms

2. Can we predict the likely changes associated with climate change? What are feedback mechanisms?

3. Prediction – some problems… Natural vs. human activity Frequency and recurrence Isolated incident or trends? Limited/unreliable historical evidence (proxy, instrumental records) Natural processes are interconnected Timescales of changes Locality/seasonal/annual Gaps in atmospheric understanding

4. Feedback mechanisms A change in one environmental factor may cause other features to change. This may have an effect on the original change, possible increasing it or reducing it. Positive – A situation where an initial change causes a reaction that increases the original change – Either temperature directly or concentrations of greenhouse gases Negative – A situation where an initial change causes a reaction that decreases the original change – Re-establish the dynamic equilibrium of gases/concentrations

5. Overview… Primary Event Atmospheric warming Secondary Reaction Cooling Secondary Reaction Further warming

6. Positive feedback…a worked example Primary event – Anthropogenic release of greenhouse gases Atmospheric warming – Changes observed in global temperature Secondary reaction – Polar ice caps/sea ice melting – Release of methane which was trapped in the ice Further heating – Due to an increased presence of methane (greenhouse gas)

7. Positive feedback…a worked example – student thoughts Primary event Atmospheric warming Secondary reaction Further heating

8. Negative feedback…a worked example Primary event – Anthropogenic release of greenhouse gases Atmospheric warming – Changes observed in global temperatures Secondary reaction – Higher temperatures and available water vapour in the atmosphere – Increased rates of photosynthesis due to optimum conditions – Increased absorption of CO 2, storage in biomass – Reduction in atmospheric CO 2 concentrations Cooling

9. Negative feedback…a worked example – student thoughts Primary event Atmospheric warming Secondary reaction Cooling