In the new BEST paper on 10 there is map of temperature changes from Jan 2000-Dec 2010 compared to Jan 1950 – Dec 1960.

1)  Why is there idea of a decade 11 years long?

2) Why 1950? I think it is dishonest. I did a quick look at the month temperature anomaly for the USA and UK and calculated the mean for each weird decade.

USA:

1930 -1940 0.39
1950 – 1960 0.17
2000 – 2010 0.65

.48C over 50 years versus .26C over 70 years.

Big difference.

UK:

1940 – 1950 0.32
1950 – 1960 0.17
2000 – 2010 0.93

.76C over 50 years versus .61C over 60 years

Not as big, but still big.

By picking 1950-60 as the starting decade, you start in a big hole and therefore you can tell lies like “1.5F over 50 years”.