Last summer headlines blared, "Hottest July in the history of the United States!" The National Climatic Data Center (NCDC) of the U.S. National Oceanic and Atmospheric Administration (NOAA) said so.
This week, NCDC is reporting the same, with the added alarm that 2012 was the warmest year on record and one of the top two years for extreme weather in America.
Climate activists are linking this to man-made global warming, ignoring that the area reported on in the NCDC reports, the U.S. contiguous states (i.e., continental America, not including Alaska), is only 2% of the Earth’s surface. So trends that may, or may not, be real in the U.S. in no way indicate global phenomena. In fact, the U.K. Met Office has admitted that there has been no global warming for 16 years and, this week, announced that temperatures are expected to stay relatively stable for another five years.
Regardless, all NCDC temperature proclamations must be taken with a large grain of salt. Here’s why.
Until the use of thermocouples became common in the U.S. climate network, temperatures were determined with mercury thermometers that have, at best, a +/-0.9°F accuracy. Even today, many stations only record temperatures to the closest whole degree. Thus, breaking the 1936 high temperature record by 0.2°F, as NCDC claimed occurred last July, is not meaningful.
All that was recorded for most of the U.S. record was minimum and maximum temperature for each day. NCDC’s so-called average daily temperatures were derived by simply computing the average of the min and max temperatures. But this is not a true average since it does not take into account how temperatures varied throughout the day.
Trusting the NCDC averaging method to come to “hottest ever” conclusions is a mistake because higher minimums at night will yield a higher daily average, even if day time highs do not rise.
This is what happened in July 2012, when, because NCDC records indicate that the U.S. was less cool at night than in July 1936, the average they computed for July 2012 was higher than in 1936. Yet, as demonstrated by Dr. Roy Spencer of the University of Alabama at Huntsville, NCDC records show that daytime high temperatures in July 1936 far surpassed those of 2012.
This week, NCDC’s credibility was further damaged when meteorologist Anthony Watts announced that he had discovered huge differences between their “State of the Climate” (SOTC) reports released each month and the actual database of NCDC temperatures. For example, the July 2012 SOTC report, issued in early August, announced that a new record had been set with the average July temperature for the contiguous U.S. being 77.6°F, one fifth of a degree higher than in July 1936. However, today NCDC say the July 2012 average was actually 76.93°F, nearly 0.7°F less. What is going on?
It turns out that, besides periodically "adjusting" the temperature database in ways that tend to lower historical temperatures, NCDC does not wait for all the data to be received before computing, and announcing, the U.S. average temperature and its rank compared to other months and years. While some stations, such as those at airports, send the data quickly via radio links and the Internet, other stations use old paper forms that arrive by mail considerably later.
When the data from lower technology sources finally arrives, NCDC update their temperature database typically “cooling” the country when all the data is used.
But neither NCDC nor NOAA tells the public and the press if, when the complete data set is analyzed, the temperature announcements in previous SOTCs are no longer correct.
Strangely, NCDC change temperature data even from the distant past without notification. For example, NCDC now assert that the average temperature in July 1936 was 76.43°F, a full degree cooler than the 77.4°F that they claimed for the month in the July 2012 SOTC report. This allows them to continue to claim that July 2012 set a record.
NCDC claims cannot be taken seriously.