What is less well known is that the alarmists do not rely on raw temperature data collected by American weather stations. Rather, the alarmists adjust the data before they publish it. This chart from NASA GISS, which you likely have seen before, purports to show the temperature anomaly as measured on land in the U.S. from 1880 to approximately the present:
But that graph, like virtually every discussion of American temperature trends that you have seen, uses “adjusted” temperature data, not what was actually reported from weather stations. This chart reflects raw data from the U. S. Historical Climatology Network, the same data that were the basis–pre-”adjustment”–for the chart above:
Michael Hammer, who created this chart from the raw data, writes:
Clearly the shape of this graph bears no similarity at all to the graph shown in Figure 4 [the first graph above]. The graph does not even remotely correlate to the shape of the CO2 versus time graph. The warming was greatest in the 1930’s before CO2 started to rise rapidly. The rate of rise in 1920, the early 1930’s and the early 1950’s is significantly greater than anything in the last 30 years. Despite the rapid rise in CO2 since 1960, the 1970’s to early 1980’s was the time of the global cooling scare and looking at the graph in Figure 5 one can see why (almost 2F cooling over 50 years).
It would appear that the temperature rise profile claimed by the adjusted data is largely if not entirely an artefact arising from the adjustments applied (as shown in Figure 3), not from the experimental data record. In fact, the raw data does not in any way support the AGW theory.
Is the United States Actually Getting Warmer? | Power Line
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