NOAA's U.S. Summers measures minimum and maximum temperature trends (June-August) from 1895 to 2024 (shown below, from NOAA's Climate at a Glance Times series data website) Compared with the calculated average temperature trend results, a clear and obvious different temperature trend with increasing growth is shown. [emphasis, links added]
The minimum temperature trend results after 1985 increased significantly faster than the maximum measured temperature trend results. U.S. population data shows that the U.S. population increased by approximately 100 million people between 1980 and 2023.
Since the average temperature is not a measured value, but the calculated mathematical average of the minimum and maximum measured temperatures {(Tmax + Tmin)/2}, The average temperature calculation trend results are controlled and governed by the larger increments that occur in the minimum measured temperature trend compared to the maximum measured temperature trend.
This difference in trends can be seen more clearly in the figure below, where the NOAA Climate Overview website time interval is divided into the 1895 to 1950 and 1950 to 2024 time intervals (where the Tavg value is controlled by Tmin rather than Tmax) They are shown in the figure below.
This result is consistent with recent research by Dr. Spencer and mirrors those shown below and found here.
Dr. Spencer also provides another study graphically shown The impact of U.S. and global temperatures on UHI from June 1850 to June 2023 is shown below. and found here.
In addition to significant population growth, the Urban Heat Island Initiative is a major driver of the increase in calculated Tavg temperature results, and these temperature measurements are also severely affected by the poor siting of NOAA's thousands of temperature measurement stations.
These thousands of improperly located temperature measurement devices do not meet NOAA/NWS siting standards.
They are too close to the artificial heat sink and will falsely increase the maximum and minimum temperature measurements, as detailed here and clearly illustrated with an example The huge system-wide measurement problem is shown below.
As stated in this report (page 18), this [2019 Oak Ridge National Laboratory measurement station data accuracy experiment showed that flawed station siting impacted temperature measurement outcomes] More time at night (The radiator's contribution to the minimum temperature is three times the contribution to the maximum daily temperature) than during the day.
NOAA evaluates changes in U.S. and global average temperature anomalies over time by using and comparing changes in calculated Tavg values over time.
As shown in the temperature measurement graph and study above, NOAA calculated Tavg growth trend values for the contiguous United States since around 1985 increased due to site survey siting deficiencies and UHI Tmin results versus Tmax measurements.
This leads to NOAA's assessment of Tavg calculations of abnormal increases in temperature over time being flawed and exaggerated.is driven by UHI impacts driven by inadequate NOAA measurement site selection and population growth, not “climate change.”
This result is also applicable to the assessment of the global Tavg temperature anomaly increasing trend calculated by NOAA.
Read the full article on Climatic Realism
