Guest post by Larry Hamlin
NOAA U.S. Continuous Summer (June-August) Measured minimum and maximum temperature trends Period 1895 to 2024 (shown below, from NOAA’s Climate at a Glance Times series) Compared with the calculated average temperature trend results, a clear and obvious different temperature trend with increasing growth is shown.
The minimum temperature trend results after 1985 increased significantly faster than the maximum measured temperature trend results.. U.S. population Data shows that the number increased by about 100 million from 1980 to 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 calculated average temperature trend results are subject to the large increases that occur in the minimum and maximum values control and domination..
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 ) respectively as 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 provided another study graphically showing the impact of UHI in the United States and globally between June 1850 and June 2023, as shown below, which can be found here.
In addition to urban heat islands (UHI), where large populations are growing, being a major driver of the increase in calculated Tavg temperature results, 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 site selection standards and are located too close to artificial radiators, thereby falsely increasing maximum and minimum temperature measurements As discussed in detail here, this huge system-wide measurement problem is clearly illustrated through an example, as shown below.
Such as this report (page 18) 2019 Oak Ridge National Laboratory measurement station data accuracy experiment The results show that the impact of defective site siting on temperature measurements is much greater at night (the radiator contribution to the minimum temperature is 3 times greater than the contribution to the maximum temperature during the day) 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 the temperature measurement graphs and studies mentioned above indicate, NOAA's calculated increasing Tavg trend values for the contiguous United States since around 1985 are clearly driven by site measurement siting deficiencies and UHI Tmin results compared to Tmax measurements. .
This results in NOAA's calculated Tavg assessment of increased temperature anomalies over time being a flawed and exaggerated statement due to inadequate NOAA measurement site selection and UHI impacts driven by population growth, not “climate change.”
This result is also applicable to the assessment of global-scale Tavg temperature anomaly increasing trends calculated by NOAA.
Relevant
