NatureOfClimateChange

= Nature of Climate Change =

Outline of Section 4: The nature of climate change (1 hour)
**(1) Data, evidence and theories** Climate change a great example of collecting data through observation and experimentation to test hypotheses. Greenhouse effect – historical context, explain the way the greenhouse effect “theory” was developed in the 1800s. Observations of atmospheric CO2 – measurements started in late 1950s at Mauna Loa, Hawaii – these observations provide a key part of the evidence of human-induced warming of the climate system. Direct temperature measurements – global temperature record goes back to 1850, lots of issues to bring out here: accuracy of measurements, bias in observations (e.g., due to urban warming?), comparing different analyses of the available data. Maybe something on observing the “effects” of climate change (e.g., – harder because you need to distinguish what is due to climate change and what to other factors. How do we “observe” climate before direct observations – palaeo and proxy data.

**(2) Climate modelling** Principles of modelling – a model is only as useful as its limitations allow, so a very simple climate model can be very useful, but it won’t tell you how rainfall might change in the future. Climate models allow climate scientists to “experiment” with the climate system, to test ideas, to test out the effect of natural and human influences on climate, to try to predict the future. Simplest climate model – based on energy balance: energy in=energy out (practical activities available with this model from SEP booklet). A more complex simple model – with effect of ocean heat uptake (practical activities available with this model from SEP booklet). Complex climate models – based on Newton’s laws of motion, plus other fundamental laws of physics.

**(3) Uncertainty** Uncertainty a key aspect of climate change. There are things we know with some certainty – the climate is warming, very likely due to humans. Things we know with less certainty – details of what will happen in the future Uncertainty about future from 2 aspects: (i) how will socio-economics change (this will affect the amount of greenhouse gases we emit (ii) how will the climate system respond Links back to climate models – large scale more certain than local details. (4) Other interesting features of climate change Timescales – climate system has long lag, so what we do (or don’t do) now will affect the climate for many decades (and centuries in the case of ice and sea level). Science and politics – international climate negotiations, science informing policy Climate change and the public – climate scepticism, politicisation of science, communicating climate change