"Actually, the deviation from 1910 to 1940 was about 0.25 degrees"
That might be a little low.
from the U of Mich. archives , before the politics got involved
see: /deepblue.lib.umich.edu/bitstream/handle/2027.42/48308/ID148.pdf?sequence=2
"CLIMATIC CHANGES OF PAST AND PRESENT
CLIMATIC CHANGES OF THE NEAR PAST AND PRESENT "   page 199 to 205

see also : Consistent near-surface ocean warming since 1900 in two largely independent observing networks @ http://onlinelibrary.wiley.com/doi/10.1029/2012GL052975/full
Geophysical Research Letters