US Air Temperature Trend - USCRN 2016 Update

Subtitle: No Warming From CO2, But There Is Some From El Niño

Figure 1.  USCRN Annual Average Temperature Anomalies, Deg C
Data from USCRN files

Analysis of the 55 temperature measurement sites with the longest records in the Contiguous States in the US Climate Reference Network (USCRN) (see footnote 1) for the years 2005-2016 (inclusive) shows a cooling trend (as reported on SLB earlier see link  and this link) until the record El Niño of 2015-16 increased the temperatures temporarily.   As shown in Figure 1, the US annual average temperature anomalies fluctuate from approximately minus 0.5 to plus 1.0 degrees C over the 12 year period for which data is available.   The annual average trend, excluding the 2015-16 El Niño, was a negative 0.0277 degrees C per year, or minus 2.78 degrees C per century.   The El Niño event changed the trend to positive 3.68 degrees C per century. 

Figure 2.  Average Anomalies for Summer months June-July-August
Data from USCRN files

As shown next in Figure 2, the temperature anomalies for summer months of June-July-August also show a modest increasing trend of 1.57 degrees C per century.  Before the El Niño, the trend was minus 0.87 degrees C per century. 








As shown next in Figure 3, the winter anomalies with the El Niño show a warming trend of 5.27 degrees C per century.  Before the El Niño event, the winter trend was minus 7.7 degrees per century.   The impact of the El Niño is most pronounced in the winter months, compared to the summer months and the US average of all months. 

Figure 3.  Average  Anomalies for Winter Months
December-January-February
Data from USCRN files

 It can be seen from the above that the modest increase in atmospheric carbon dioxide, CO2, of approximately 2 ppm per year over the period 2005-2016 had essentially nothing to do with the temperature trends in the pristine locations that have the USCRN measurement stations. However, the major impact was the El Niño event that started in 2015 and extended into 2016.  In the US, the El Niño was expected to create warmer, drier conditions in the South, and wetter, cooler conditions in the West.   The jet stream carried most of the rain to the north of California, however, so the state did not have much rain until the winter of 2016-17.  

As written before on SLB see link, many actual causes exist for measured warming in the near-surface atmosphere, none of which are increased CO2.   It is a colossal error for scientists to mis-attribute an effect (warming) to a false cause (increased CO2) when many other known causal factors exist.  Indeed, those known causal factors are the primary reason the USCRN was developed, funded, and put in place.   The non-CO2 causal factors include increased population density in cities, increased energy use per capita, reduced atmospheric pollution, increased local humidity from human activities (lawn watering, industrial cooling towers), changed site conditions from rural to urban, long-term drought, and wind shadows from buildings in cities.  

An eighth causal factor can be added to the list, as the data presented here clearly demonstrates: short-term warming from an El Niño event.    As the months and years go by without another El Niño, it is expected that the USCRN 55 stations will show a decreasing trend in summer, winter, and overall average temperatures.   

Footnote 1):  "The USCRN's primary goal is to provide long-term temperature, precipitation, and soil moisture and temperature observations that are of high quality and are taken in stable settings." -- NOAA webpage.    By “stable settings,” NOAA means that the locations are far from human warming influences such as cities, airports, and industries, and are expected to not have their present conditions change over the next several decades.    The stations have automatic sensors, redundancy, and automatic data upload to computer databases.   The intent is to have reliable, unbiased data without gaps and relocation issues. The oldest station began operating in July, 2001 in Asheville, North Carolina.   The next-oldest station began operating in January, 2002 in Kingston, Rhode Island.    By December of 2004, 60 stations were operating.  Of those, 55 stations were selected for this study.  The 55 stations provide a geographically widespread set of stations dating back to December, 2004, thus 10 years of complete data were available by January, 2015. -- end footnote 1. 

Roger E. Sowell, Esq.

Marina del Rey, California
copyright (c) 2017 by Roger Sowell - all rights reserved

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