Statistical Shenanigans — A global climate story

Today I thought I’d offer a primer on statistical manipulation.  I am going to take reputable data, cherry pick information and “prove” that global warming since WW II began has been less than advertised.   Here we go.

Let’s begin with the East Anglia University World Temperature Graph

Compare the warming between 1942 and 1991 (or 1878 if you prefer).  The change has been about .1 degree C increase in 50 years.  The climate change shown in this chart before 1950 is presumed by climate hawks to be natural warming (or cooling).

Now lets look at the latest UAH satellite climate data:

Now compare the data for the period beginning in 1991 and ending with the current data (March 2013) as shown on the UAH data set.   No net change.  So the world warmed about .1 degree C. in the 50 years from 1941 to 1991 and there has been no net change since then.  A world that is supposed to be warming isn’t.

Wow.

I started at a high point.  The answer would have been quite different if I had chosen 1976 as my starting point.   Or 1910 or 1965.  But if I had chosen to begin in …..say…. 1878, I could have shown even slower warming.  Statistical misrepresentation is all about data selection.

The IPCC knows how to select data and present it to their advantage. My last post quotes the IPCC’s 2007 Climate Synopses.  I’ll repeat one of my favorite paragraphs here:

Since the IPCC first report in 1990, assessed projections have suggested  global temperature increases between 0.15 and 0.3  degree C per decade from 1990 to 2005.  This can now be compared with with observed values of about 0.2 degree C per decade, strengthening confidence in our near-term projections.

The statement appears not to match data.  Conveniently the IPCC doesn’t quote a source.  I wonder what data they used?  Not UAH or East Anglia.  Perhaps they didn’t start in 1990. The only way that I can get the arithmetic to match is to start in 1992.   1992 was a very cold year because of the eruption of Mt Pinatubo.  World temperatures dropped about .2 degree C in 1992 because of the volcano.  If there is any year that should not be used as a starting point when calculating climate data, it is 1992.

When I use 1990 or 1991 or 1993 the increase is much less than the .2 degree C stated.  The increase is between .1 degree C and  .15 degree C, depending on the temperature source used and start date selected.  If I had started in 1998 instead, the data would have shown very slight net cooling.  Clearly the IPCC cherry picked data.

The IPCC appears to have ignored temperature variability shown in the East Anglia data that they call natural climate variation in their 2007 AR4 report.  If natural climate variation can produce lower temperatures (and higher temperatures too) for long periods of time, how can you assume any specific set of values supports any specific position?

The IPCC cherry picked data…and then assumed that data proved they were right.  Sloppy science and arrogance displayed in a single paragraph at the most quoted climate document ever produced, the 2007 AR4 Climate Synopses Report, section 3.2.

A few years ago NASA direct temperature data started in 1860 and it showed rapid warming and rapid cooling in the 1870’s.  Today NASA data begins in 1880, while East Anglia still begins in 1850. Why did the NASA data change.

I suspect data manipulation….and SWAG.

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