Dr Phil Jones back in drivers seat with CRUTem4 updated land only global temperature data – warms more than the UKMO CRUTem3 and with remarkable early outliers from RioApril 13th, 2012 by Warwick Hughes
CRUTem4 is just released and shows more warming than the UK Met Office dominated CRUTem3. Before I get on to CRUTem4 – a quick reprise of my Jan 2007 post commenting on CRUTem3 compared to our old friend of many years CRUTem2 (which ended in 2005). “Huge variations now between the 3 main global T datasets – January 31st, 2007″. I argued the view the that one reason for UKMO getting involved in CRUTem3 was they wanted to reduce excess warming in CRUTem2 northern high latitudes – more on that in another post where I will explore where CRUTem4 finds the extra warming.
I downloaded global and hemispheric trends from the official CRU website, CRUTem2 and CRUTem3 and 4.
CRUTem2 is from 1856-2005 while CRUTem3 and 4 run 1850-2010.
So I ran the MS Excel linest function for the 1856-2005 period for all 3 series, global, northern & southern hemispheres.
And for 1850-2010 for CRUTem3 and 4. Results summarized in this matrix – all trends are degrees C per decade.
The global differences chart shows the effect of the warming adjustments in CRUTem4 in the last 20 years – and cooling adjustments in CRUTem4 from ~mid 1850′s to 1890. (obviously cooling those years warms the overall trend). Note that from 1895 to the mid 1980′s the CRUTem4 minus CRUTem3 differences are small. The warmth in 1852 will be discussed later but stems from Rio de Janeiro data.
The northern hemisphere differences chart shows the effect of the warming adjustments in CRUTem4 in the last 20 years – and cooling adjustments in CRUTem4 from 1850′s to mid 1870′s. Note again that from the mid 1870′s to the ~1990 the CRUTem4 minus CRUTem3 differences are small.
The southern hemisphere differences chart shows the effect of the warming adjustments in CRUTem4 in the last 5 years – and cooling adjustments in CRUTem4 from the late 1850′s to ~1885 – much of which comes from adjustments to Australian grid boxes. (obviously cooling those years warms the overall trend). Note that from ~1895 to 2005 the CRUTem4 minus CRUTem3 differences are small. The outlier warmth in 1851-1852 stems from Rio de Janeiro data and we will investigate this in later articles.
Note that the Jones team already have some extra warmth built in for the CRUTem5 version – whenever that appears. They only have to adjust out the warm early years from Rio – and presto – there is a little more warming in the trend.
Added after comment #1.
Using the “Land” data from this University of Alabama at Huntsville site.
CRUTem3 warms much faster than the satellites and CRUTem4 faster still.
The period is to 2010 because CRUTem4 is not yet updated through 2011.
IMHO the CRU team consider themselves beyond effective scrutiny.