During Hansen’s 1999 admission that the US wasn’t experiencing any climate change, he unveiled his earlier magic trick – corrupting the Northern Hemisphere temperature record.
How can the absence of clear climate change in the United States be reconciled with continued reports of record global temperature? Part of the “answer” is that U.S. climate has been following a different course than global climate, at least so far. Figure 1 compares the temperature history in the U.S. and the world for the past 120 years. The U.S. has warmed during the past century, but the warming hardly exceeds year-to-year variability. Indeed, in the U.S. the warmest decade was the 1930s and the warmest year was 1934. Global temperature, in contrast, had passed 1930s values by 1980 and the world has warmed at a remarkable rate over the last 25 years.
Pretty graphs. The only problem is that the National Academy of Sciences issued a very different graph of Northern Hemisphere temperatures in 1975 – which was essentially identical to Hansen’s 1999 US graph.
The two graphs are shown overlaid below. Hansen’s 1999 US graph was closely tracking the rest of the Northern Hemisphere – the exact opposite of what Hansen claimed in 1999.
Now compare vs. Hansen’s Northern Hemisphere graph.
The next image is an overlay of the National Academy of Sciences 1975 Northern Hemisphere graph on Hansen’s Northern Hemisphere graph. Hansen knocked a few tenths of degree off all years prior to 1940.
Conclusion, at some point prior to 1999 Hansen tampered with the Northern Hemisphere data, and later used that as the basis to justify tampering with the US data.