Models of reality

NZCSC chairman Barry Brill has suggested to Environment Waikato that its Regional Policy Statement (RPS) should not be influenced by the climate change ‘Guidance Manuals’ (here and here) issued by the Ministry for the Environment in early 2008. Like the IPCC’s Fourth Assessment Report (4AR), their recommendations have been overtaken by recent scientific papers and data. His submission notes that modelled projections of 21st century warming rely upon two components – emission volumes and climate sensitivity. Here is his comment regarding Climate Sensitivity.

CLIMATE SENSITIVITY (Model Uncertainties)

1: THE IPCC REPORT

The 17 models used for the 4AR produced a 2100 temperature range of 1.8°C – 4.4°C. Note at page 122 of the Manual, “this arises from taking the best estimate temperature change, and subtracting 40% to get the low end, and adding 60% to get the high end of the range”. The “most likely” temperature trend is 2.7C per century. Continue Reading →