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Examination of Historical Temperature Records and Data Adjustments

Examination of Historical Temperature Records and Data Adjustments

Feb 2, 2024
Climate Realism

Examination of Historical Temperature Records and Data Adjustments

The accurate recording and interpretation of historical temperature data are critical for understanding climate trends. This article aims to scrutinize the adjustments made to historical temperature records and how these modifications may impact the perceived trends in global and United States temperature data. The manipulated data is often used to fear monger about cataclysmic climate change that does not exist.

Historical Temperature Coverage

Coverage of historical temperature data varies significantly across regions. In the United States, the coverage since 1895 is comprehensive, but in contrast, regions such as South America, Africa, the Middle East, and much of Asia have sparse historical data. This discrepancy poses challenges for calculating reliable long-term global temperature trends.

Temperature Records and Predictions

In 1984, James Hansen of NASA predicted substantial global warming, with specific forecasts for the United States. However, by 1999, Hansen noted a declining temperature trend in US data, which did not align with the lower-quality global temperature trend that was showing warming.

Data Adjustments: The US Temperature Record

Early data adjustments, around 2005, mainly impacted data post-1960, with a modest total adjustment of about half a degree Fahrenheit. These adjustments were primarily attributed to time of observation bias, a factor with some scientific validity. Yet, recent adjustments have increased significantly, now estimated to be four to five times greater than those made 20 years ago, with time of observation bias accounting for only a minor component.

Impact of Data Adjustments

Adjustments made by NOAA and NASA have turned a cooling trend in the United States temperature record into a warming trend. The original data showed a strong correlation between average summer maximum temperatures and the frequency of days above 90 degrees Fahrenheit (r-squared of 0.91). After adjustments, this correlation weakens substantially (r-squared of 0.56), suggesting that the data adjustments may undermine the credibility of the temperature dataset.

Examination of the Data Tampering Allegations

Allegations of data tampering suggest that historical temperatures have been cooled by more than one degree Fahrenheit, while recent temperatures have been warmed by a similar amount. The extent of these adjustments has reportedly increased by approximately 400% over the past two decades.

Forensic Analysis of Temperature Data and Carbon Dioxide Correlation

Analyses indicate an apparent correlation between the amount of carbon dioxide in the atmosphere and the degree of adjustment applied to US summer temperature data (r-squared of 0.97). This suggests that adjustments could be aligning more closely with carbon dioxide theory rather than with empirical temperature data.

Global Temperature Record Concerns

The global temperature record is considered to have lower quality compared to the US record, with limited data availability and documentation of historical observation practices. Despite this, five different scientific groups have published global temperature trends with remarkable agreement, showing minimal variance. This poses questions about the reliability of these trends given the stated inadequacies of global temperature data coverage.


The analysis of historical temperature data and subsequent adjustments made by scientific authorities raise critical questions about the integrity of climate datasets. While adjustments to account for biases such as time of observation are scientifically justified, the scale and rationale for recent modifications to both US and global temperature records warrant further investigation. It is essential that temperature data adjustments maintain transparency and adhere strictly to scientific methodologies to ensure the credibility and reliability of climate change research.


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