Watts Up With That notes a significant divergence by Japanese climate scientists versus the U.S. for global surface temperatures since 2000--Japanese calculations are .25 degrees Celsius cooler than NASA or the NOAA. Watts notes that the issue isn't the difference, but how the difference was arrived at. He concludes:
So, it appears that Japan’s Meteorological agency is using adjusted GHCN data up to the year 2000, and from 2001 they are using the CLIMAT report data as is, without adjustments. To me, this clearly explains the divergence when you look at the NASA plot magnified and note when the divergence starts. ...Read the whole thing.
... If anyone ever needed the clearest example ever of how NOAA and NASA’s post facto adjustments to the surface temperature record increase the temperature, this is it.