John Coleman, co-founder of the Weather Channel, with a post at Watts Up with That?
Was July 2012 the hottest July in United States history? Was the last 12 months period the warmest ever? NOAA,the National Oceanographic and Atmospheric Administration, says “Yes”. The agency released a map and statement in early August stating without reservation that July 2012 and the last 12 months were the hottest ever. The national media gave the report a “headline play” as we say in the media business. And, many of the media stories linked this hot weather with global warming.
However, skeptical scientists have produced studies that show that the last 15 years have seen a cooling in the United States. This is the NOAA NCDC Climate at a Glance US annual mean temperature trend the last 15 years.
No doubt it has been very, very hot and very, very dry. But if you check the facts behind these reports the claims are not all that certain. Consider this; the data behind the NOAA claims shows the average temperature in July 2012 was only 2/10ths of one degree warmer than July 1936. And there are several papers posted on the internet that claim that if the temperatures and the means of processing the data had not been “adjusted” several times in the past 50 years, 1934 would still be the warmest year ever, considerably warmer that the last 12 months.
I conclude that while there is some basis for the NOAA record warmth position, those who challenge NOAA’s claims also make good cases. And it seems to me that while the recent hot, dry weather is clearly out of the ordinary, as it stands for now, it is not the sort of extreme event that might prove global warming. And, any connection between the hot, dry weather and warming caused by the activities of mankind remains totally unproven.
It’s a long, meaty p0st, well worth your time. One more excerpt:
…There were no actual thermometers until after 1724 when a man named Fahrenheit made the very first one. All temperature data before that is calculated using such methods as analyzing tree rings and ice cores. While the scientists who do that work are certain that they produce accurate data, there are all sorts of issues such as what type of tree rings to use, the geographic distribution of the trees, how to figure the temperature since other issues such as the amount and time of rainfall also influence the tree’s growth. And ice cores are clearly only in the polar regions and mountain glaciers, and don’t represent the entire world temperature pattern. I can accept basic trends from these systems, but I have trouble believing they produce temperature records with the accuracy of greater than ±2 or 3 degrees.
As for the thermometer, the early ones were crude; tubes of colored mercury were stapled onto wooden backboards with degree markers printed on them. How accurate a temperature reading can you get from looking at something like that? I conclude that you should not regard those readings to be accurate within a tenth of a degree. And actually I am skeptical of even ±one degree…