The discussion about Anthropogenic Global Warming (AGW), or the theory that atmospheric gases generated by mankind are causing global temperatures to rise, is becoming rather uncivil. Many proponents of AGW deny that any criticism of the theory is valid while critics of AGW are labeled as 'deniers' of 'settled science' so rarely is there a civil debate of the situation. The AGW proponents predict many global catastrophes due to the warming temperatures caused by more CO2 (carbon dioxide) including melting ice caps, rising sea level, and various negative impacts on the plant and animal life on Earth. The AGW proponents are strongly pushing for severe reductions on CO2 emissions by industry, which will have accompanying impacts on the world’s future economic health. If this prediction for future disaster has no scientific foundation (i.e., man-made CO2 is not causing global warming) then the impacts on people and industry will have been unnecessary. The AGW proponents have been associating just about every natural phenomenon (whether weather or ecological) over the past few decades with global warming and that unscientific fear mongering becomes tiresome. Unfortunately, it had initial traction among many (scientist or not) due to the warmer temperatures in the 1980’s and 1990’s so many could believe the claims of that association, regardless of whether the association was scientifically valid.

Another page in this web site looked at local (Wisconsin) temperature trends and found that the 1930’s were warmer than the decades before or after that decade and after a few decades of cooling (the 1970’s global cooling scare), the two decades at the end of the 20th Century were cooling. Locally, the temperatures over the past few years of this decade have been decreasing.

The trends in the national temperatures have also been analyzed. Using the ‘raw’ NASA GISS temperature data (not the ‘combined’ or ‘homogenized’ alternate selections among the three GISS options), an attempt was made to find at least locations in each state having a complete (or very nearly complete) temperature record from the present to before 1900 (many records began in 1895, a few even earlier but none before 1881). This was not always successful, with Connecticut having only one suitable location but a location on Long Island was used for a second nearby source for that state. For appropriate regional comparisons, larger states had more sites to get a fairer distribution (e.g., a similar number of square miles per site). 140 locations in the 50 states were used for this national analysis. Most of the temperature data records were first collected from the GISS site in late December, 2009 but in April 2009 the records were updated (when the 2009 data became available and to collect a few more sites for the improved distribution) and the various charts were updated.

Each state has its own Excel spreadsheet to include the same analyses: graph the annual temperatures for the locations in this state, graph a rolling 10-year average temperature (e.g., the plot for year 1999 is the average for the ten years 1990 through 1999) for the locations in this state, calculate and graph the average temperature per decade for each location, and plot the average temperature during each solar sun spot cycle at each location.

After that state-by-state analysis, a summary of regional and national trends was generated. Here are the averages for those locations scattered across the 49 states (Alaska is separate due to no records being long enough to average with those from the other states), first in Celsius and then in Fahrenheit.





Next the average temperature per decade was calculated and graphed, first in Celsius and then in Fahrenheit.





There is a definite ‘U’ shape to the national temperatures, both in the graph of annual temperatures and in the graph of average temperature per decade. The 20th century started cooler, the 1930’s were warmer, the following decades were cooler, and the end of the 20th century was warmer. The graph of annual temperatures also shows temperatures have been cooling since 1998, an unusually warm year.

Admittedly, the distribution of the locations used in this analysis did not provide a uniform distribution across the national geography. Some states are much smaller than others so that alone makes a ‘fair’ distribution impossible when starting with states. In an attempt to show these trends are not an illusion due to the selection of the locations with the temperature records, the collection was separated into four regional groups. Here is an Excel spreadsheet that shows the distribution of locations (to get a roughly similar square miles per location in each region). Here is a text file that lists the locations in all the states and a few samples of the temperatures. Here is a Word document with the links to the GISS data for all the locations, as well as the latitude and longitude (from GISS) for each location.

The Northeast included: CT, DE, ME, MD, MA, NH, NJ, NY, PA, RI, VT, VA, WV.
The Southeast included: AL, AR, FL, GA, KY, LA, MS, NC, OK, SC, TN, TX.
The Midwest included: IL, IN, IA, KS, MI, MN, MO, NE, ND, OH, SD, WI.
The West included: AZ, CA, CO, HI, ID, MT, NV, NM, OR, UT, WA, WY. AK is in this region but not in this average.

The average temperature for each region is graphed, first in Celsius and then in Fahrenheit. The same general trends observed in the local data and in the national data are also observed in the regional collections.





More information about the Northeast region can be found in its web page.





More information about the Southeast region can be found in its web page.





More information about the Midwest region can be found in its web page.





More information about the West region can be found in its web page.

The same rough U-shape (warming in 1930’s, cooling in 1960’s, warming in 1990’s) is observed in all the regional temperature graphs.

The Southeast and Midwest regions reveal a similar overall behavior not seen in the other two regions because for these the average temperature in 1896 is almost the same as the average temperature in 2009. In the Midwest, 2009 is actually cooler than in 1896.

The Northeast and the West regions have a distinct overall upward slope from the start to the end that is not found in the other regions. The Urban Heat Island (UHI) effect has been discussed where surface temperatures in metropolitan areas might increase as the population increases. An attempt was made during the selection of locations to avoid if possible any large metropolitan areas to prevent that possible UHI distortion. The regional presentation might reveal the presence of UHI in the one region having many metropolitan areas among a limited group of candidate locations.

The levels of CO2 in the Earth’s atmosphere have been increasing at a gradual rate for roughly the past 250 years (according to the data from CDIAC extending back about one thousand years), from about 280 parts per million in the late 1700’s to our current level of about 385 parts per million. A comparison of the changes in CO2 levels with the changes in the annual temperatures over the past Century does not reveal a close relationship.





Tinkering with the respective scaling in the above chart can get overlaps of the two trends. The CO2 chart has a gentle positive slope that increases in the last quarter century. The temperatures are warmer in the 1930’s, cooler in the 1970’s, and warmer at the end. The CO2 level has no corresponding significant ups and downs in this time span.

If the CO2 generated by mankind were truly the driving force behind the recently observed temperature changes in the 1980’s and 1990’s then it is not clear how it could also be involved with the cooling during the 1960’s and 1970’s. Historians have noted that the earth was much warmer 1000 years ago, in a span called the Medieval Warm Period, and the earth was much cooler a few hundred years ago, in a span called the Little Ice Age. The temperature record reveals several periods of distinctly warmer and cooler temperatures have taken place in recent history (i.e., the past 2000 years). Since AGW assumes CO2 causes only warming (and climate models used by AGW proponents predict catastrophic warming with further increases in CO2), AGW has no practical explanation for any of those recorded climate changes except for that warming period recorded between 1980 and 2000. AGW does not explain warmer temperatures prior to the 1940’s and the cooler temperatures that followed. Mankind has been responsible for a slight increase in CO2 levels. It is not logical to treat CO2 as a significant global threat because it is responsible for warmer temperatures for only two decades in the 20th century while ignoring all the other climate changes in history where the temperature changes did not align with changes in the mankind-generated CO2 level. There is much more to climate change than just CO2 levels.

David Archibald and others have suggested a connection between solar sun spot cycles and temperature trends. Here is a 60-page presentation (pdf) about the possible explanations for climate change involving CO2 and solar sun spot cycles. Since the basis for the national trends was the annual temperatures, the respective monthly temperatures were not directly available for this calculation (without substantial effort) so a rough 10 year span was used for each solar cycle rather than using the particular ‘month in year’ for the start and end of each cycle. Even with this approximation, a rough relationship is seen between the length of the sun spot cycles and the average national temperature during that cycle. The shorter cycles are slightly warming (upper left) while the longer cycles are slightly cooling (lower right). There is one cycle that is high in the middle, more off the pattern (about one degree F) seen from the other cycles; this point is the most recent cycle 23 that contained the unusually warm year of 1998.





While this rough relationship might not be conclusive (where all the points are exactly on a charted line), it still represents a more viable contribution to the temperature trends over the past century than CO2. CO2 levels were essentially in a continuously increasing mode while temperature trends were alternately warming and cooling. Increasing and decreasing amounts of energy from the Sun seems to have an effect on the Earth. The above charted relationships reveal that the sun spot cycle length (that is related to the Sun’s energy level) has some influence on temperature trends, though it is apparently not the only influence since the data points are not all on a single straight line. The AGW proponents tend to focus on CO2 to the exclusion of other possible influences since CO2 control is apparently the goal more than understanding the Earth’s climate.

The UN IPCC and others are recommending severe curbs on mankind’s generation of CO2 based on the assumption that an increasing CO2 level is always related to increasing temperatures even though the above charts using the temperatures analyzed from all 50 states do not reveal such a relationship. Others have shown that global temperatures follow similar patterns to those shown in this web page (such as this or the Skeptics Handbooks, two pdf documents).

Here are links to the accompanying regional presentations:
Midwest Temperature Trends
Northeast Temperature Trends
Southeast Temperature Trends
West Temperature Trends

After this analysis was completed, temperature data records from locations around the world were analyzed. The results of that analysis can be found here.

The various Excel spreadsheets for this web page can be obtained from the author at dave at cultureandreligion.com.


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created - Jan. 2010
last change - 04/11/2010