This morning I noticed at Jennifer Marohasy’s post http://jennifermarohasy.com/2014/01/last-year-2013-a-hot-year-for-australia/
a comment from “Luke” (who else) objecting to my use of 2nd order polynomials in yesterday’s post. Strictly I should stick to linear trends for a 35 year timescale, and use polynomials only for much longer periods. Therefore, here is a plot of Australian annual minima and maxima for the 104 years from 1910 to 2013, using data straight from the BOM.
Note that the red 2nd polynomial curve (maxima) shows a fairly flat trend until the 1950s, with an increasing rise since then. (Yes! It’s getting hotter!)
Note how the blue (minima ) curve also gradually rises over the years and apparently continues to do so.
Since the mid 1980s there is a divergence in trends. Daytime temperatures are rising faster than night time temperatures.
This is a problem because increasing CO2 and other greenhouse gases should be slowing back radiation, which should be evident in night time temperatures increasing faster.
Something else is happening.