In 1984, NASA’s James Hansen predicted 4-5C warming for the US.

Wayback Machine

Fifteen years later Hansen was upset that the US wasn’t warming as he predicted.

NASA GISS: Science Briefs: Whither U.S. Climate?

So they started tampering with the data. In the 2005 USHCN documentation, US temperature adjustments were 0.5F. Since then the adjustments have quadrupled.

Wayback Machine

This graph of US temperatures was posted by NASA in 1999, showing a strong cooling trend from the 1930’s through the end of the century. The years 1934 and 1998 are circled.

 

NASA 1999

And this is NASA’s current graph, which now shows a strong warming trend during that period.

 

NASA 2019

There has been a sharp decline in hot summer afternoons in the US

Wyoming – State Climate Summaries 2022

There is a close correlation between summer average maximum temperature and number of 90F days.

The correlation between the measured temperature data and number of 90 degree days is high, with an R^2 of 0.91.

But after the data is adjusted, the correlation collapses – indicating that their data tampering has lowered the quality of the data.

The adjustments track CO2 with a very high correlation of 0.97, so you can predict the amount of data tampering based on atmospheric CO2.

Climate alarmists  argue that the high correlation between average maximum temperature and number of 90 degree days is due to most older stations having their min/max thermometer reset in the afternoon. (Time of Observation Bias.) It is easy to eliminate that by using only stations which reset their thermometers in the morning, but the result is the same as for the set of all stations.  Data tampering makes the data worse, not better.

 

Same story with afternoon stations

Another problem with the final adjusted database is they make up fake data for stations which are not reporting.  We can eliminate that by using only stations with a 100 year long record. That changes the results very little

According to climate scientists, the very high quality and well documented US temperature record needs to be adjusted by several degrees reversing the trend, but they all agree very closely about the incoherent, undocumented and grossly inadequate global temperature record.

World of Change: Global Temperatures

“Although reasonably good records of instrument type and observing practices are maintained for stations in the U.S., the types of instrumentation and observing practices are most often unknown for stations outside the U.S.”

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