When it comes to global warming, the Japanese can’t quite get their minds right. Anthony Watts explains:
Each year, four international science institutions compile temperature data from thousands of stations around the world and make independent judgments about whether the year was warmer or cooler than average. “The official records vary slightly because of subtle differences in the way we analyze the data,” said Reto Ruedy, climate scientist at NASA’s Goddard Institute for Space Studies. “But they also agree extraordinarily well.”
Well, sort of. But beginning in 2001, Japanese scientists’ estimates of global surface temperatures have diverged from the other three countries, as this graph shows:
You need to read Watts’s entire post to get the details, but what is happening here is that beginning in 2001, the Japanese stopped using the “adjusted” Global Historical Climatology Network data, and started using temperatures as actually measured:
[I]t 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. The annotation marks in magenta are mine:
This illustrates a point we have made repeatedly: the supposed increase in global temperatures in recent decades is largely due, not to raw temperature data, but rather to adjustments to that data that are made by global warming zealots who, in many instances, have an enormous financial interest in propagating the AGW theory. Watts illustrates the point (which he makes more gently than I just did) with this chart. It shows temperature data from the Darwin, Australia airport from 1880 to the present. Based on actual temperature measurements, it has been getting cooler in Darwin. But adjustments to the raw data create a fictitious warming trend:
Are these adjustments justified? I really, really doubt it. At a minimum, I would like to see them defended by someone who doesn’t have a major financial stake in global warming politics.